tubular tires
mco...@cornell-iowa.edu
What's with this tale of tubulars becoming unstuck during descents?
I've been riding tubs for 25 yrs, including loaded touring in the
Rockies and the Sierra Nevadas during the summer mos. and have never
had that problem. Stop spreading this lame slander of the best
bike-pavement interface available! Persons who gripe about tubular
repair probably balk at lubing their chains and overhauling their b/bs
and h/ss and hubs, etc; the a dditional time required for repair of
tubs is more than offset by the extra time and hassle required to
change a clincher. I mean, your 3000# car rides on clinchers---don't
you think your svelte 20-something # bike deserves a more
bike-specific solution, something elegant and appropos?
Nor
--
Use Control-G or Gold-G to load signature file (mail.signature)
into EDT or EVE(TPU) editor
Marty Condon
Department of Biology
Cornell College
Mount Vernon, IA 52314
319/895-4154
FAX: 319/895-4492
mco...@cornell-iowa.edu
Jobst Brandt
Marty Condon writes:
> What's with this tale of tubulars becoming unstuck during descents?
There's truth to it.
> I've been riding tubs for 25 yrs, including loaded touring in the
> Rockies and the Sierra Nevada during the summer mos. and have never
> had that problem.
Oops! You just revealed that you either weigh less than 100 lbs or
you have never descended a steep road that required braking for any
distance.
> Stop spreading this lame slander of the best bike-pavement interface
> available! Persons who gripe about tubular repair probably balk at
> lubing their chains and overhauling their b/bs and h/ss and hubs,
> etc; the additional time required for repair of tubs is more than
> offset by the extra time and hassle required to change a clincher.
So what's your point? Are you telling us that the tubular tire is
vanishing from the bicycle scene through some conspiracy, or what is
it you are proposing? Rims of a bicycle with a single rider reach
temperatures of 250 deg F on a 10% grade with a series of hairpin
turns. This has been measured on the Nufenen Pass in Switzerland.
Rim glue is soup at this temperature.
Jobst Brandt <jbr...@hpl.hp.com>
GBSHAUN
>Message-id: <6e6dmc$p...@hplntx.hpl.hp.com><BR>
><BR>
>Marty Condon writes:<BR>
><BR>
>> What's with this tale of tubulars becoming unstuck during descents?<BR>
><BR>
>There's truth to it.<BR>
><BR>
>> I've been riding tubs for 25 yrs, including loaded touring in the<BR>
>> Rockies and the Sierra Nevada during the summer mos. and have never<BR>
>> had that problem. <BR>
><BR>
>Oops! You just revealed that you either weigh less than 100 lbs or<BR>
>you have never descended a steep road that required braking for any<BR>
>distance.<BR>
><BR>
On the contrary, the surprise you express at Martys quite typical observation
is suggesting to me that your experiences with tubulars were probably hampered
by the use of incorrect glue or gluing protocol. I don't use anything fancy,
just 3M, yet have never had a tire creep, role, twist or anything. Now I don't
have quite 25 years experience racing crits and in the mountains, but then
again I don't exactly tip the scales at 100lbs.
Not quite sure why this thread has caused so many half-truths etc to be quoted
in the defense of clinchers. Can't find the posting, but someone even "informed
us" that clinchers are no more suseptable to "snake-bike" type punctures than
tubulars. - Come on now, get real!
SW
Jobst Brandt
G B Shaun writes:
> On the contrary, the surprise you express at Marty's quite typical
> observation is suggesting to me that your experiences with tubulars
> were probably hampered by the use of incorrect glue or gluing
> protocol.
If you are using pressure sensitive glue that is designed to allow a
tire change to a spare that has similar glue, it is thermally
sensitive as well. No doubt track glue, once hard, dies not
appreciably soften with heat. Glues that remain tacky are all on a
sliding scale of fluidity and that is why the tried and true glues
used by racers for a hundred years have thermal problems.
> I don't use anything fancy, just 3M, yet have never had a tire
> creep, role, twist or anything. Now I don't have quite 25 years
> experience racing crits and in the mountains, but then again I don't
> exactly tip the scales at 100lbs.
So you haven't come across a descent that generates much heat. There
are plenty of those here in the SF area and even more in the Alps.
You are drawing conclusions from narrow experience and applying it to
all.
> Not quite sure why this thread has caused so many half-truths etc to
> be quoted in the defense of clinchers.
What you mean is that you are alluding to things without saying that,
for instance, "tubular glue doesn't melt". You just say all the
others are wrong. Speak for yourself.
> Can't find the posting, but someone even "informed us" that
> clinchers are no more susceptible to "snake-bike" type punctures
> than tubulars. - Come on now, get real!
Tubes are susceptible to snake bites and if you use latex tubes, as
the tubulars that are relatively immune to this kind of flat do, then
your clincher will also not have such punctures. Maybe you can
explain why you believe tubulars get fewer snake bite flats. If you
understand the process, you should be able to explain it.
Jobst Brandt <jbr...@hpl.hp.com>
Garry Lee
Rims of a bicycle with a single rider reach
>temperatures of 250 deg F on a 10% grade with a series of hairpin
>turns. This has been measured on the Nufenen Pass in Switzerland.
>Rim glue is soup at this temperature.
I've had the extraordinary experience of ungluing a patch on the inner
aspect of a tube while descending a road in West Cork that averages more
than 10% and reaches 30% in one spot. THis was on a mountainbike. I can
well believe the soup story.
Propeloton
-Seems many of you think the 'trouble' of tubulars are somehow not worth it....
-Like many things in cycling-if installed correctly-like Campag Delta
brakes-will provide increased performance in actual riding-not just in a overly
technical discussion of the scientific nuances of the 'gear'-
-I have two DeRosas set up identically except the San Remo has clinchers on
Torelli box section rims(made by Ambrosio)/36 hole tied and soldered and the
Giro has tubulars on Campagnolo Sigma Pave' 36 hole-tied and soldered-all 14
gauge spokes and I can CERTAINLY tell a difference when I ride them-the Tubies
feel much more supple/comfy/faster-the tubies are Vittoria Formula UNO-not hand
made-the clinchers are Conti Super Sport Ultras-
-The difference is the same with Conti tubies and Michelen clinchers-
-OBTW I get far more flats on the clinchers than I do on the sew-ups-not
empirical data I know but real world experience.
Peter
ProPeloton
Boulder, USA
Tullio
Jobst Brandt wrote:
> > I don't use anything fancy, just 3M, yet have never had a tire
> > creep, role, twist or anything. Now I don't have quite 25 years
> > experience racing crits and in the mountains, but then again I don't
> > exactly tip the scales at 100lbs.
>
> So you haven't come across a descent that generates much heat. There
> are plenty of those here in the SF area and even more in the Alps.
> You are drawing conclusions from narrow experience and applying it to
> all.
So, then, the heating of tubular glue is really only a concern in a few,
isolated areas. Most folks do not live or ride in an area that has the
type of descents that are found in San Francisco or the Alps. So, which
is the "narrow experience?"
I do not disagree with your contention that glue will soften under
prolonged braking. However, I am not convinced that this is relavent
for most cyclists. Certainly not for those of us in the Midwest.
Todd
Tullio's Big Dog Cyclery
LaSalle, IL
e-mail: tul...@TheRamp.net
Raleigh-Specialized-Bianchi
Waterford-Torelli-GT/Dyno
Burley-Co-Motion
Jobst Brandt
Peter Prope writes:
> -Seems many of you think the 'trouble' of tubulars are somehow not
> worth it.... -Like many things in cycling, if installed correctly,
> like Campag Delta brakes will provide increased performance in
> actual riding, not just in a overly technical discussion of the
> scientific nuances of the 'gear'-
Are you suggesting there is an incorrect way to install the Delta
brake and that is the way all the people who threw it out, including
Campagnolo, did it? Maybe this is more difficult than I assumed.
Could you explain what the trick is?
Meanwhile, the same goes for tubulars. It seems that most people who
don't have a follow car, and even many of these, use clinchers. What
is it we are missing here? I rode tubulars for many years and taught
a course in tubular repair for the local racers. Opening, patching,
boot installation, stem replacement and tube replacement were all
tasks that people could learn, but not easily. You could read about
it in the FAQ however.
> -I have two DeRosas set up identically except the San Remo has
> clinchers on Torelli box section rims(made by Ambrosio)/36 hole tied
> and soldered and the Giro has tubulars on Campagnolo Sigma Pave' 36
> hole-tied and soldered-all 14 gauge spokes and I can CERTAINLY tell
> a difference when I ride them-the Tubies feel much more
> supple/comfy/faster-the tubies are Vittoria Formula UNO-not hand
> made-the clinchers are Conti Super Sport Ultras- -The difference is
> the same with Conti tubies and Michelen clinchers- -OBTW I get far
> more flats on the clinchers than I do on the sew-ups-not empirical
> data I know but real world experience.
Whew! That's a long sentence without scuba equipment.
Well, I can't compete with that, having only one bicycle and with
plain untied spokes. I'm sure your tubulars are strongly affected by
the "supple/comfy/faster" wheels with tied spokes. You ought to let
the TdF teams in on your technique. They seem to have forgotten about
all this.
I can tell that your bike shop is filled with myth and lore and I
guess that is a marketable quantity. Don't try to sell me on it
though.
Jobst Brandt <jbr...@hpl.hp.com>
THolland63
Jobst Brandt asked (somebody else):
> tubulars get fewer snake bite flats.
When and if you do bottom a tubular rim against the tire tread, a broader
surface makes contact. The relatively narrow flange of the clincher rim is
more likely to pinch. I've only pinch-flatted a tubular on two occassions, but
have had "snake bites" bring down many a clincher. Also, almost all of my
tubulars use butyl tubes, so it's not the latex that saved them.
But you must have heard that before, so bring the hammer down . . .
Todd Holland
Jobst Brandt
Tod who? writes:
>>> I don't use anything fancy, just 3M, yet have never had a tire
>>> creep, role, twist or anything. Now I don't have quite 25 years
>>> experience racing crits and in the mountains, but then again I don't
>>> exactly tip the scales at 100lbs.
>> So you haven't come across a descent that generates much heat. There
>> are plenty of those here in the SF area and even more in the Alps.
>> You are drawing conclusions from narrow experience and applying it to
>> all.
> So, then, the heating of tubular glue is really only a concern in a few,
> isolated areas. Most folks do not live or ride in an area that has the
> type of descents that are found in San Francisco or the Alps. So, which
> is the "narrow experience?"
Oh don't be so difficult. I mentioned these two areas to show that
the problem is not local. Of course there are flat land areas where
this is not a problem, but then most sports bicycle riders aren't found
there. The point is that most people who have much riding experience
with tubulars, other than criterium racing, have melted the glue on
their tubulars,
> I do not disagree with your contention that glue will soften under
> prolonged braking. However, I am not convinced that this is
> relevant for most cyclists. Certainly not for those of us in the
> Midwest.
That may be, however, because tubular glue for the road is tackyto
make a tire change possible, it works in place with each wheel
revolution. This is apparent from the dark grey color on the tire
caused by aluminum oxide that is abraded from the rim by tire
movement. It is along those two dark zones near the edges of the base
tape that the tape wears through and when it does, a blowout is not
far away.
I have not only my tires, but those of many racers who attended tire
patch sessions at my house in the days of self sponsored, tubular tire
riding racers. I still have bags of these old dried out (aged) tires
in my hall closet. We were glad when Specialized introduced the
Touring II clincher, because it ended the Wednesday evening sewing
sessions.
One of the last tubular riders came out on a Sunday ride a few years
ago with other riders who now carry only a tube and patch kit. He got
a slow leak and because the tire was old and he was unaware that he
was the only one with a tubular, he was about to throw the old rag
away. I remind him that it was his only spare for the rest of the
ride, even if it was a slow leaker.
As it turned out his "spare" blew out in the stitching (where the rim
sockets had worn through the base tape) so it was back to the leaker
that leaked faster with every pumping. At a creek crossing, I filled
his tubular with water, using my Silca pump by removing the piston to
fill the chamber with water. With the valve at the top, all air could
be pushed out as the tire filled with water. This was good enough to
ride home and for several days thereafter. He no longer rides tubulars.
Jobst Brandt <jbr...@hpl.hp.com>
David Balfoort
THolland63 wrote:
> When and if you do bottom a tubular rim against the tire tread, a broader
> surface makes contact. The relatively narrow flange of the clincher rim is
> more likely to pinch. I've only pinch-flatted a tubular on two occassions, but
> have had "snake bites" bring down many a clincher.
Why do so many riders report pinch flats with clincher tires? I've had some with
mtb tires but I don't recall ever having one with a road clincher. I'm 180 lbs.
and I'm not the most fluid rider in the area so there must be some other
explanation. Opinions please.
Thanks,
David
John Many Jars
In article <6e9hdp$o...@hplntx.hpl.hp.com>,
Jobst Brandt <jbr...@hpl.hp.com> wrote:
>Whew! That's a long sentence without scuba equipment.
>
>Well, I can't compete with that, having only one bicycle and with
>plain untied spokes. I'm sure your tubulars are strongly affected by
>the "supple/comfy/faster" wheels with tied spokes. You ought to let
>the TdF teams in on your technique. They seem to have forgotten about
>all this.
>
>I can tell that your bike shop is filled with myth and lore and I
>guess that is a marketable quantity. Don't try to sell me on it
>though.
is he always this charming?
Mark Barton
Jobst Brandt wrote:
>
>
> As it turned out his "spare" blew out in the stitching (where the rim
> sockets had worn through the base tape) so it was back to the leaker
> that leaked faster with every pumping. At a creek crossing, I filled
> his tubular with water, using my Silca pump by removing the piston to
> fill the chamber with water. With the valve at the top, all air could
> be pushed out as the tire filled with water. This was good enough to
> ride home and for several days thereafter. He no longer rides tubulars.
>
Can you get all the air out, so that it's behaves like a
solid rubber tire?
Do I understand correctly, that the tire loses water slower than air?
How does this work?
Mark Barton
zed
In article <6e6dmc$p...@hplntx.hpl.hp.com>, jbr...@hpl.hp.com (Jobst Brandt) wrote:
>Marty Condon writes:
>
>> What's with this tale of tubulars becoming unstuck during descents?
>
>
>Oops! You just revealed that you either weigh less than 100 lbs or
>
>> Stop spreading this lame slander of the best bike-pavement interface
>> available! Persons who gripe about tubular repair probably balk at
>> lubing their chains and overhauling their b/bs and h/ss and hubs,
>> etc; the additional time required for repair of tubs is more than
>> offset by the extra time and hassle required to change a clincher.
>
>So what's your point? Are you telling us that the tubular tire is
>vanishing from the bicycle scene through some conspiracy, or what is
>temperatures of 250 deg F on a 10% grade with a series of hairpin
>turns. This has been measured on the Nufenen Pass in Switzerland.
>Rim glue is soup at this temperature.
>
And Jobst,
Why did you elude to this fact and wait untill someone questioned it
do you back up your (yes i will admit you are correct Jobst)point with
facts that most of the people you have scared away will never duplicate.
Hey, let's forget about land mines, STOP ALL CYCLIST FROM GOING DOWN
THE Nufenen Pass!!!!!!!!!
Most people think trolls are schmucks who post "wHere CAN EyE Get
Warrezz", I think I know of a different meaning.
zed
ud...@biosys.net
(Spambots-- please replace "biosys" with "nospam" before scanning)
John Everett
In article <6ea3aq$gn0$1...@clarknet.clark.net>, han...@clark.net says...
Heavens no, sometimes Jobst can be a real curmudgeon.
--
jeve...@wwa.DEFEAT.UCE.BOTS.com (John Everett) http://www.wwa.com/~jeverett
^^^^^^^^^^^^^^^
Things have gotten so bad I feel the need to disguise my email address.
And I don't like this explanation because I just hate long signatures.
Jobst Brandt
Mark Barton writes:
>> As it turned out his "spare" blew out in the stitching (where the rim
>> sockets had worn through the base tape) so it was back to the leaker
>> that leaked faster with every pumping. At a creek crossing, I filled
>> his tubular with water, using my Silca pump by removing the piston to
>> fill the chamber with water. With the valve at the top, all air could
>> be pushed out as the tire filled with water. This was good enough to
>> ride home and for several days thereafter. He no longer rides tubulars.
> Interesting. What's it like to ride such a tire? Can you get all
> the air out, so that it's behaves like a solid rubber tire?
As I said, with the stem at the top the air can be gotten out by
squeezing the tire as it fills until only water comes out of the
valve. Then fill it hard. There is a degree of elasticity left from
the casing.
> Do I understand correctly, that the tire loses water slower than air?
> How does this work?
The viscosity of water is enormously greater than of any gas so the
leak rate is thousands of times lower.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Zed snipes anonymously:
> Why did you elude to this fact and wait untill someone questioned it
> do you back up your (yes i will admit you are correct Jobst)point
> with facts that most of the people you have scared away will never
> duplicate.
I can't predict whether poseurs are going to set themselves up with
all sorts of hypothetical nonsense. That rims get sizzling hot is
known to many riders and those who have to write tutorials about the
contrary will have to suffer their own presumptuousness. I don't
understand why you think I should protect these people from exposure.
We have had enough long, drawn out exchanges where the poseur ups the
ante at every turn, finally reaching for brinkmanship with "are you
calling me a liar". There have been plenty of these classics.
Jobst Brandt <jbr...@hpl.hp.com>
Emilio Castelli
I have been riding tubulars since I started biking in 1989 (not that
long I guess) and I have ridden them ever since. I have been riding both
in the Alps (I lived in Italy 1986 trough 1995) and in the US (mostly
Sonoma and Marin, but I've ridden some of the Colorado Rocky Mountains).
Descent included in my 'palmares" are:
Valcava (first 2 km from top)
Mortirolo (the steep side)
Stelvio (the steep side)
Marmolada (Steep side of Fedaia)
Alp d'Huez
Fort Ross
Tre Cime
…..
Objective advantages of tubulars:
1- Lighter wheel
2- Faster to change in case of flat
3- Impossible to get a second flat caused by debris left in the
clincher. This has happened to me three times on my MTB. The first time
I was just stupid; the second and third time I checked where the hole
was, found the thorn in the tire, removed the thorn, changed the
tube….guess what, I had two holes and the second thorn was still in
there, ready to flatten my tube).
4- Less likely to get snake bites (the rim has no sharp edges that can
cut into the tube and the tube is more protected)
5- If you break a spoke, you can change it without having to take the
tire off
Debatable advantages of tubulars
1- Better ride
2- Better cornering
3- Less overall flats; with clinchers people tend to ride on worn out
tires a lot more. In my experience, unless you get a flat from a nail, a
thorn or something sharp, tubulars tend to last a "fixed" (depending on
the tubular) amount of miles. When they are worn out, they tend to get
flats from road debris that would not cause flat when new. Clincher
riders will fix the tube and ride again on the worn out tire quickly
getting another flat.
Objective disadvantages of tubulars:
1- If you get two flats the same day, you are in trouble. This has
happened to me only once and the main reason was that my spare was an
old rag, not a spare tire. Still, you can ride home on a flat tubular.
Olano was very happy to have tubulars on his bike when he won the worlds
in Colombia. With clinchers he would have needed a wheel change and
Indurain would have won the worlds.
2- If you do not know how to brake, you will roll the sucker, rip the
valve right off and fall hard especially since you do most braking with
your front wheel. I rolled my tubulars fairly often my first year of
biking but never to the point of ripping the valve off. I used to stop
halfway down a descent and turn the front wheel around to "straighten"
the tubular back in position. Then someone explained to me that you are
not supposed to "ride your brakes" on a bike. Never had a problem since.
3- I have never ridden a loaded touring bike nor a tandem but I do not
think these would be the best applications for tubulars.
Choice is good.
Emilio
Jobst Brandt
Emilio Castelli writes:
So why did you send me this as personal e-mail? I don't need any more
copies than the rest of the readers on the net. Cut it out!
> I have been riding tubulars since I started biking in 1989 (not that
> long I guess) and I have ridden them ever since. I have been riding both
> in the Alps (I lived in Italy 1986 trough 1995) and in the US (mostly
> Sonoma and Marin, but I've ridden some of the Colorado Rocky Mountains).
So what? On my first tour in the Alps I also rode plain old tubulars
without special insulator strips between tire and rim, but the tires
walked around on the rims just the same.
You seem not to know that all sports bicycles were equipped
exclusively with tubulars before the introduction of high performance
clinchers about 20 years ago. As soon as they demonstrated
reliability, anyone who built wheels switched. These people had
suffered enough. Now you are going to tell us that they were all
wrong and that Clement, Pirelli, Sieber and others should still be in
the business even though they went broke when they were abandoned by
the users.
By the way, you didn't say how much you weigh either.
Jobst Brandt <jbr...@hpl.hp.com>
BC Holicky
>
> Oh don't be so difficult.
Perhaps it is you who should not be so difficult.
I have been riding tubulars for 14 years, racing and training, and have
not yet had a problem with melting glue. Before you start saying that
that is due to the fact that I'm small or that I don't ride any steep
descents, I weigh 175lbs and live in Boulder, CO. There are a couple of
'hills' around these Rocky Mountains, ya know? BTW - I just use boring
old 3m fasttack or conti tub glue - nothing special.
It all comes down to knowledge of proper braking technique. Selecting a
rim with a greater amount of area helps also, as it provides a greater
amount of surface area through which to lose heat. (Course, these rims
are usually slightly heavier, but then again, like I said, I weigh 175lbs
- which is why God made Mavic Reflex 36 hole rims).
Yes, I have been the only one in a group ride on tubs. Yes, I have
flatted, and yes, I have flatted my spare. It sucks. It's happened twice
in 14 years that I've flatted twice on the same ride. That's not a whole
heck of an incovenience.
So feel free to ride your clinchers. I would appreciate it if you could
keep your misguided (and frankly, poorly informed) opinions of tubs
either to yourself or state that they are just your opinions. I do have
a mountain bike. I do ride clinchers on that, obviously. My wife rides
clinchers. Lots of my friends ride clinchers. They are quite convenient
if they flat, and carrying a spare for them is alot lighter.
Yet I still choose to ride tubs everyday, training and racing. They have
not yet been able to prove that I am clinically insane, so there must be
a reason that I put up with these small hassles.
To me, what it feels like to be riding is the most important thing -
that's the reason I ride. In my opinion, clinchers feel like riding a
skateboard, while tubs feel like riding a wave. There is nothing like
cranking out an incline on a silky smooth ride, or sailing around a turn
like you're riding on a air. It's an enormous difference.
And if THAT didn't matter, I might as well sign up for a spinning class.
BC Holicky,
Boulder, CO
BikeTires
This is purely a personal response and in know way associted with the
organization you normally would see the E-Mail address attached.
I simply don't feel like wasting the time trying to log in again as myself and
redigging up the banter I have run across here. Furthermore I can't help
myself, just too much "JB" this time.
I could respond to many of the "Known Facts" (actually JUST LIKE EVERYONE
ELSE's opinion) including anything I post. The "known fact's as posted
mostly as attacking reply's by Jobst. But as I have said before it's purely a
waste of time. So I won't elaborate that glues have changed in the last five
years, I won't mention that the one's he has experience with have changed or
gone, I won't mention that neither Specialized or Avocet make tubulars or have
ever. I won't bring it up that we are now in the late 90's. I won't mention
to him that there are other bike shops beyond the realms of bay area and heck
there are even a few who know what the heck is going on in todays bike
industry. (BTW - I have been to Pro-Peloton, no myth or lore at all, just a
real nice shop with real good people, they cater to all road markets very
well, but they are Exceptional at the Pro level.) So... >I can tell that
your bike shop is filled with myth and lore as stated by Jobst, I say really
Jobst? How can you tell? Have you Been there?
Enough said, other than, much like you and yours, I also have an Opinion.
At times you post some very valuable information, but more often than not you
really leave a nasty taste in the mouth of bike industry. It is really too
bad,
Mike Sullivan
Personal response
GBSHAUN
><BR>
>I have been riding tubulars for 14 years, racing and training, and have <BR>
>not yet had a problem with melting glue. Before you start saying that <BR>
>that is due to the fact that I'm small or that I don't ride any steep <BR>
>descents, I weigh 175lbs and live in Boulder, CO. There are a couple of <BR>
>'hills' around these Rocky Mountains, ya know? BTW - I just use boring <BR>
>old 3m fasttack or conti tub glue - nothing special.<BR>
><BR>
etc etc.
Exactly,
My experiences over a similar period have been the same (160lbs, inc. Palomar
mtn - 5200'). And I very much doubt we're alone.
You know I seem to recall many T-d-F riders descending some serious mountains
for many decades, yet I can't seem to recall a regular occurance of tires
rolling off (I'm sure it has happened, just as mechanics have been known to
make mistakes adjusting gears etc too).
Now don't go telling me they're all sub-100lbs, or that the T-d-F mountains are
not really big.
I'm glad clinchers have been developing over the past decade, for some people
it's helped. If you like them, ride them. I even have a pair myself. But I've
no idea where these strange scare stories have come from, or why some people
feel compelled to spread them as they do. Perhaps sensible advice regarding
mounting them would be more helpful.
SW
VCopelan
bike...@aol.com (BikeTires) writes:
> I won't mention that neither Specialized or Avocet make tubulars or have
>ever.
Avocet did market tubulars with their name on them a few years ago. They were
made by Vittoria!
Propeloton
Thank you Mike for the nice words-maybe Jobst will visit someday and see for
himself-
Peter
ProPeloton
Rick Denney
On 15 Mar 1998 02:31:15 GMT, gbs...@aol.com (GBSHAUN) wrote:
>
>You know I seem to recall many T-d-F riders descending some serious mountains
>for many decades, yet I can't seem to recall a regular occurance of tires
>rolling off (I'm sure it has happened, just as mechanics have been known to
>make mistakes adjusting gears etc too).
>Now don't go telling me they're all sub-100lbs, or that the T-d-F mountains are
>not really big.
>
I can't find it now, but I remember reading in Greg Lemond's book
about anticipating such problems on a long descent, and using it to
tactical advantage. He said that the combination of a hot day and a
long descent would cause glue to melt and tires to roll, or slip,
shearing their valve stems, and, sure enough, this happened. Much of
what he says about bicycle design and structure is urban legend and
silly tradition, but this is actual experience from a very experienced
top pro. So this phenomenon is something Tour riders are especially
aware of, and it is a problem for them. It's not a question of tires
being improperly glued, it is a question of the properties of the glue
itself, and the conditions.
Now that I think about it, it may have been someone else's book
(Hinault? Doughty?), but the point is the same.
Rick Denney
Take what you want and leave the rest.
John Forrest Tomlinson
In
<4942E37ACB0477AE.CDC7C297...@library-proxy.airne
s.net> rde...@mail.viggen.com (Rick Denney) writes:
>
>
>
>On 15 Mar 1998 02:31:15 GMT, gbs...@aol.com (GBSHAUN) wrote:
>
>>
>>You know I seem to recall many T-d-F riders descending some serious
mountains
>>for many decades, yet I can't seem to recall a regular occurance of
tires
>>rolling off (I'm sure it has happened, just as mechanics have been
known to
>>make mistakes adjusting gears etc too).
>>Now don't go telling me they're all sub-100lbs, or that the T-d-F
mountains are
>>not really big.
>>
>
>I can't find it now, but I remember reading in Greg Lemond's book
>about anticipating such problems on a long descent, and using it to
>tactical advantage. He said that the combination of a hot day and a
>long descent would cause glue to melt and tires to roll, or slip,
>shearing their valve stems, and, sure enough, this happened. Much of
>what he says about bicycle design and structure is urban legend and
>silly tradition, but this is actual experience from a very experienced
>top pro.
Ron Kiefel reported the same thing on a descent in the Pyrenees.
JT
Don Saleski
Just out of curiosity, which clincher tire company do you own so much
stock in to put forth such a diatribe against tubular tires? One of my best
friends and I ride tubulars exclusively, and while they blow out once in a
while (no more often than you'd PINCH FLAT a clincher, NB: tubulars don't
pinch-flat), once you take into consideration the cost of a cheap tubular
tire (Super Condor, Futura) and the weight savings in the most important
part of the bike (lighter rims and lighter tire-tube structure), the
sew-ups win. I have your book "The Bicycle Wheel", and am forever grateful
for the guidance it has given me in wheel building, but there is a
perceived difference between tubulars and clinchers, in favor of the
tubulars, and I believe you are being unduly harsh on them
If I show up on one of your club rides, don't worry. My fanny-pack holds
two tubular spares, as well as the rest of my onboard maintenance.
kindest regards,
Don Saleski
Jobst Brandt <jbr...@hpl.hp.com> wrote in article
<6e9ocp$o...@hplntx.hpl.hp.com>...
> One of the last tubular riders came out on a Sunday ride a few years
> ago with other riders who now carry only a tube and patch kit. He got
> a slow leak and because the tire was old and he was unaware that he
> was the only one with a tubular, he was about to throw the old rag
> away. I remind him that it was his only spare for the rest of the
> ride, even if it was a slow leaker.
>
> As it turned out his "spare" blew out in the stitching (where the rim
> sockets had worn through the base tape) so it was back to the leaker
> that leaked faster with every pumping. At a creek crossing, I filled
> his tubular with water, using my Silca pump by removing the piston to
> fill the chamber with water. With the valve at the top, all air could
> be pushed out as the tire filled with water. This was good enough to
> ride home and for several days thereafter. He no longer rides tubulars.
>
> Jobst Brandt <jbr...@hpl.hp.com>
>
PTGEMG
>David wrote:
>Why do so many riders report pinch flats with clincher tires? >mtb tires but
I don't recall ever having one with a road clincher. >I'm 180 lbs.
>and I'm not the most fluid rider in the area so there must be some
1) It's because they don't bother to pump their tires before they ride.
I'm 205 lbs and know I can't get away with that. I pump the tires every ride
even if I rode the day before. Overkill? Maybe, maybe not. I had one flat
last year, and it was a puncture.
I got this tip from a husky bike mechanic years ago.
2) Ultra narrow tires combined with above.
Racing chic overcomes common sense: @ 205 I have no use for 700 x 18 tires and
even 20's are questionable. Talking with tire tech reps has led me to use 23
width tires as a minimum.
My 2 cents, but it gives me something to talk about waiting for other riders to
fix their "mystery flats"!
Pete in PA
Adam Rice
In article <01bd509a$41bc7f60$848ca3ce@hp-customer>, "Don Saleski"
<NOsa...@proaxis.comSPAM> wrote:
> Just out of curiosity, which clincher tire company do you own so much
> stock in to put forth such a diatribe against tubular tires?
Avocet.
> One of my best
> friends and I ride tubulars exclusively, and while they blow out once in a
> while (no more often than you'd PINCH FLAT a clincher, NB: tubulars don't
> pinch-flat),
Yes they do. I just patched one a few days ago.
> once you take into consideration the cost of a cheap tubular
> tire (Super Condor, Futura)
I'd rather ride on clinchers than cheap tubulars--I've had nothing but bad
luck with them.
I ride tubulars exclusively as well (I can get away with this because I
don't live in the Alps).
Adam Rice | adam...@crossroads.net
Austin TX USA | http://www.crossroads.net
Jobst Brandt
B C Holicky writes:
>> Oh don't be so difficult.
> Perhaps it is you who should not be so difficult.
You can't fool physics. If the energy must be dissipated in the
brakes, then the rim will get hot. There is no way to make that go
away. Pressure sensitive glues, ones that are tacky as road tire
adhesives are, are also temperature sensitive. Thus, as the rim
heats up, the glue becomes more fluid.
> I have been riding tubulars for 14 years, racing and training, and
> have not yet had a problem with melting glue. Before you start
> saying that that is due to the fact that I'm small or that I don't
> ride any steep descents, I weigh 175lbs and live in Boulder, CO.
> There are a couple of 'hills' around these Rocky Mountains, ya know?
> BTW - I just use boring old 3m fasttack or conti tub glue - nothing
> special.
Yes, the Rocky Mountains are often cited as examples of challenging
slopes on the basis of their high altitude. This is deceptive, there
are steep roads most anywhere where there are mountains and Colorado
is not alone in that. There are always back roads that are steep in
mountainous regions. However, passes in the Rockies in particular,
have mild gradients, so much so that the Union Pacific rail line over
Tennessee Pass, at over 11000 ft elevation, has a maximum 2% grade
with no loops and curves to gain altitude. Highways in the Rockies
are noted for their flat gradients.
> It all comes down to knowledge of proper braking technique.
> Selecting a rim with a greater amount of area helps also, as it
> provides a greater amount of surface area through which to lose
> heat. (Course, these rims are usually slightly heavier, but then
> again, like I said, I weigh 175lbs - which is why God made Mavic
> Reflex 36 hole rims).
The area of the rim has no significant effect on this, but rather the
weight, because more weight can store more heat in the metal. You may
suggest riding extremely heavy rims in the mountains, but I doubt
you'll convince many riders of that tactic. Peak temperatures are
achieved within one braking, so increasing rim mass is the primary
defense. Besides, let's not bring religion into the tubular glue
discussion.
> Yes, I have been the only one in a group ride on tubs. Yes, I have
> flatted, and yes, I have flatted my spare. It sucks. It's happened
> twice in 14 years that I've flatted twice on the same ride. That's
> not a whole heck of an inconvenience.
So why do you do it?
> So feel free to ride your clinchers. I would appreciate it if you
> could keep your misguided (and frankly, poorly informed) opinions of
> tubs either to yourself or state that they are just your opinions.
I haven't seen that you disagree with my assessment of the failings of
tubulars and that most riders have chosen to not use them for these
and possibly other reasons.
> I do have a mountain bike. I do ride clinchers on that, obviously.
> My wife rides clinchers. Lots of my friends ride clinchers. They
> are quite convenient if they flat, and carrying a spare for them is
> alot lighter.
So why do you do it?
> Yet I still choose to ride tubs everyday, training and racing. They
> have not yet been able to prove that I am clinically insane, so
> there must be a reason that I put up with these small hassles.
Yes? Let's get to the bottom of this.
> To me, what it feels like to be riding is the most important thing -
> that's the reason I ride. In my opinion, clinchers feel like riding
> a skateboard, while tubs feel like riding a wave. There is nothing
> like cranking out an incline on a silky smooth ride, or sailing
> around a turn like you're riding on a air. It's an enormous
> difference.
Are you sure this isn't something you perceive and that is may not be
measurably so? Acoustic effects often affect perceptions and a light
weight tubular with a latex tube has a different ring to it. Rolling
resistance measurement have not supported your belief. As I mentioned,
the plasticity of rim glue absorbs more energy than clinchers, even
though the tubular has less casing and tread loss, primarily because
there is less of it to absorb energy.
> And if THAT didn't matter, I might as well sign up for a spinning
> class.
What do you intend to spin, besides tubular tales?
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Mike Sullivan writes:
> (BTW - I have been to Pro-Peloton, no myth or lore at all, just a
> real nice shop with real good people, they cater to all road markets
> very well, but they are Exceptional at the Pro level.) So... I can
> tell that your bike shop is filled with myth and lore as stated by
> Jobst, I say really Jobst? How can you tell? Have you Been there?
Fortunately, I don't have to make the trip because the myth and lore is
posted right here on wreck.bike. I'm glad you got all your opinions
off your chest with out addressing to any of the items of proof that
I presented.
> Enough said, other than, much like you and yours, I also have an
> Opinion. At times you post some very valuable information, but more
> often than not you really leave a nasty taste in the mouth of bike
> industry. It is really too bad,
The taste is made of the material offered by "the bike industry" and
only gives that impression when the purveyors of this stuff are
confronted by it. I don't understand why you blurt out such an ad
hominem response to technical points I make, unless I'm hitting too
close to home.
Jobst Brandt <jbr...@hpl.hp.com>
BC Holicky
My, my, we get testy quickly, don't we? Well, lets take a look at what
you have to say, Jobst my boy.
Thus, as the rim
> heats up, the glue becomes more fluid.
Exactly. Which is why you learn to brake correctly - braking in the
correct manner (as in, not riding the brakes) will cause less heat build
up than pumping the brakes, and give the rims time to cool off in between
braking sessions.
. Highways in the Rockies
> are noted for their flat gradients.
Yup - that's because they have very large trucks traveling on them. THIS
IS WHY WE DON"T RIDE THERE! Since when have you ridden on a 4 lane
interstate? We ride the back roads - come on out - I'll show you a
grade. We'll start at flagstaff mountain where Phinney, Keifel and
others used to hone their pro climbing and descending techniques. It's
just *slightly* more than a 2% grade. Next thing you know, you'll be
arguing that the Rocky's are basically flat, but are only perceived to be
sloped due a disturbances in light waves.
> The area of the rim has no significant effect on this,
(Jobst is refering to the ability of a rim to counteract heat gain)
You are absolutely dead wrong. The wider the braking surface (ie the
more exposed rim area) the faster it will cool between braking sessions
due to greater contact with the cooler air around it. Weren't you the
one who said 'you can't fool physics'? Go buy a physics book - learn it
before you spout it.
>
finally, i said
> To me, what it feels like to be riding is the most important thing -
> that's the reason I ride. In my opinion, clinchers feel like riding
> a skateboard, while tubs feel like riding a wave. There is nothing
> like cranking out an incline on a silky smooth ride, or sailing
> around a turn like you're riding on a air. It's an enormous
> difference.
then Jobst said
> Are you sure this isn't something you perceive and that is may not be
measurably so? Acoustic effects often affect perceptions and a light
weight tubular with a latex tube has a different ring to it. Rolling
resistance measurement have not supported your belief. As I mentioned,
the plasticity of rim glue absorbs more energy than clinchers, even
though the tubular has less casing and tread loss, primarily because
there is less of it to absorb energy.
This is a riot. Now you're telling me that I'm hearing things. You
start off by saying that I need to be more scientific in my 'defense' of
tubulars and then you finish off your misguided diatribe by saying that I
like tubs better because, perhaps, they SOUND better?!?! Jobst, you are
a fool, and when you come up with something like this it makes that all
too obvious to the rest of us. I never once said that I like tubs
because they are faster. I don't give two hoots whether the glue of a
tub rim absorbs more energy than a clincher or vise versa. I said they
FEEL better to ME. Does that threathen you somehow? Chump. You blow
your PERCEIVED shortcomings of tubulars way out of proportion, and then,
when I (and others) call you on it, you try to come up with some
blustery, psuedo(heavy on the psuedo)scientific defense of your position,
just like a child who lacks the self-confidence to allow that perhaps
they were a bit wrong.
I will reiterate that tubulars are a bit more work and worry than
clinchers. There are not prohibitavely so, however. Quite frankly, to
me, and to many, many others, tubulars feel (oh - right - and sound) so
much better beneath us that we would gladly put up with 5 times the
hassle to have them on our bikes. Those folks who use clinchers are more
than welcome to prefer them - perhaps some day I'll change my tune. Just
because YOU don't like something doesn't mean that everybody else HAS to
feel the same way. (typical kindergarten lesson provided as a public
service announcement for Jobst, who must've missed that day of class)
BC Holicky,
Boulder, CO
BC Holicky
it should read that the correct manner in which to brake is to pump them,
as opposed to riding them.
Sorry for the mistake.
(gosh, jobst - I admitted I was made a mistake in typing!!! How can I
live with myself?)
BikeTires
As stated previously a purely personal response in no way associated with the
attached E-mail address.
My response is very simple, you often submit very positive and useful
information, however you are also the king of flame based on your own opinions
and what you perceive as proven fact. So I believe your "proof" is purely your
opinion. As with anything in any industry a person can make a graph,
schematic, report, etc. state just about anything you want it to state. You
feel this incessant need to to attack anything that doesn't directly correlate
with your own opinion. In my own opinion you are much better at and more
qualified than I am in blurting "ad hominem" responses, mainly because I
couldn't find your quoted term in any dictionary. But if I am correct in what
you are saying you are better at it.
To hack back at a Professional Retailer or a consumer purely because it doesn't
meet your idea of the correct is arrogant and a very vivid display as to one of
the numerous problems the bike industry of the U.S. faces today. A tremendous
number of cyclists and potential cyclists read the numerous posts on the
newsgroups daily. You could actually add a tremendous amount of information,
however you feel an incesant need to grab inate and mundane points and turn
them into something bigger than they truly are. For what? Who knows only
Jobst's mind does.
So publicly I say to any future cyclists reading this as well as any person who
chooses to read and/or respond to a Jobst Brandt post, make sure it's really
as big an issue as he has made it seem, get more opinions, read how much
flame posts he gets as opposed to anybody else who is sharing their opnions.
After all this entire post is just my opinion.
One other thing directly Jobst. I am not sure what you are talking about
regarding "hitting too close to home" Most of your points have nothing to do
with or have no direct relation to anything the products I am associted with
and how they are marketed or are simply so far out in left field that they
arent't worth addressing. The bike shop and consumer decides whether these
products work or not. We will let them decide.
Best regards,
Mike Sullivan
Personal Response
VCopelan
bc...@frii.com (BC Holicky) Writes:
>Thus, as the rim
>> heats up, the glue becomes more fluid.
>
>Exactly. Which is why you learn to brake correctly - braking in the
>correct manner (as in, not riding the brakes) will cause less heat build
>up than pumping the brakes, and give the rims time to cool off in between
>braking sessions.
Don't flame me, but I thought that pumping the brakes still results in fairly
high rim temperatures? When you pump the brakes, you actually apply the brakes
with extra force (over those who ride them) but over shorter time intervals.
My experience is that the net result is about the same... i.e. the rims get
mighty hot. No, I never did roll a tubular in the hills but those "skateboard
like" clinchers do inspire more confidence on the descents.
Jobst Brandt
BC Holicky writes:
> My, my, we get testy quickly, don't we? Well, lets take a look at
> what you have to say, Jobst my boy.
If that isn't a testy reply, I haven't seen any. I am not your boy.
>> Thus, as the rim heats up, the glue becomes more fluid.
> Exactly. Which is why you learn to brake correctly - braking in the
> correct manner (as in, not riding the brakes) will cause less heat build
> up than pumping the brakes, and give the rims time to cool off in between
> braking sessions.
When approaching a sharp turn after a long fast section, braking in
advance of the turn, or pumping the brakes has no effect on the amount
of heat that goes into the rim, nor how much is cooled. The time to
dissipate the heat is governed by how fast air flows over the rim after
leaving the turn and how long before the next such brake application
must be made. Brake pumping is useless in minimizing rim heating.
On the other hand, I would welcome an explanation on how it could
effect heating, considering the duration of braking.
>> Highways in the Rockies are noted for their flat gradients.
> Yup - that's because they have very large trucks traveling on them. THIS
> IS WHY WE DON"T RIDE THERE! Since when have you ridden on a 4 lane
> interstate? We ride the back roads - come on out - I'll show you a
> grade. We'll start at flagstaff mountain where Phinney, Keifel and
> others used to hone their pro climbing and descending techniques. It's
> just *slightly* more than a 2% grade. Next thing you know, you'll be
> arguing that the Rocky's are basically flat, but are only perceived to be
> sloped due a disturbances in light waves.
I think you missed the point that the rockies are not what makes the
roads steep but the roads you choose to ride on. We have steep roads
here, in Britain, the Alps and elsewhere. I see only that the Rockies
are put forth as the test of ones mettle for no other reason than that
they are high.
>> The area of the rim has no significant effect on this,
(Jobst is refering to the ability of a rim to counteract heat gain)
> You are absolutely dead wrong. The wider the braking surface (ie the
> more exposed rim area) the faster it will cool between braking sessions
> due to greater contact with the cooler air around it. Weren't you the
> one who said 'you can't fool physics'? Go buy a physics book - learn it
> before you spout it.
That is only the case if you are using rims whose surface is otherwise
insulated, like Spinergy or other non metallic rims. You may be
visualizing Shamal rims that aren't what people use for descending
steep mountain roads. The difference between all the regular all
purpose rims on the market lies primarily in their thermal mass, but
even that is largely the same except that tubular rims are a bit
lighter.
You might have the courtesy to not call my writing spouting. This
does little to further understanding of why rims get hot. As you may
know, tandems have this problem to such a degree that their tires
explode off the rim. Pumping these brakes has equally little effect.
> To me, what it feels like to be riding is the most important thing -
> that's the reason I ride. In my opinion, clinchers feel like riding
> a skateboard, while tubs feel like riding a wave. There is nothing
> like cranking out an incline on a silky smooth ride, or sailing
> around a turn like you're riding on a air. It's an enormous
> difference.
Well that is what is claimed, just as shaving legs has many benefits,
yet when questioned, the proponents retort with name calling and
repetitions of that it is better, no reasons or repeatable proofs
being offered. That tubular heating has always been a problem for
steep descents that require braking, has been attested by other
writers who have offered quotes from professional racers whose opinion
is often cited in these pages.
>> Are you sure this isn't something you perceive and that is may not
>> be measurably so? Acoustic effects often affect perceptions and a
>> light weight tubular with a latex tube has a different ring to it.
>> Rolling resistance measurement have not supported your belief. As
>> I mentioned, the plasticity of rim glue absorbs more energy than
>> clinchers, even though the tubular has less casing and tread loss,
>> primarily because there is less of it to absorb energy.
> This is a riot. Now you're telling me that I'm hearing things. You
> start off by saying that I need to be more scientific in my
> 'defense' of tubulars and then you finish off your misguided
> diatribe by saying that I like tubs better because, perhaps, they
> SOUND better?!?!
We have read various items including those of the press that rhapsodize
about "The Singing of the Setas" and the like. There is merit to a
low loss tire but it isn't big enough to make a measurable difference.
That you deny the acoustic affect doesn't stop others from talking
about it.
> Jobst, you are a fool,
Well I guess that settles it.
> and when you come up with something like this it makes that all too
> obvious to the rest of us. I never once said that I like tubs
> because they are faster.
You use the word "us" and then say you didn't mention it. Either you
are trying to speak for the tubular faithful or you are not. The
claim that tubular tires are faster is the most often proffered
argument. That you don't believe it may set you apart from others,
but that does not mean it is not an issue.
> I don't give two hoots whether the glue of a tub rim absorbs more
> energy than a clincher or vise versa. I said they FEEL better to
> ME.
So now you say it's aesthetics. That's OK with me but the outset of
this discussion was that tubulars are superior to clinchers and that
those who don't use them are not informed. I have no argument with
people who like to ride them, it's the proposition that the rest of
bicyclists are ill informed.
> Does that threathen you somehow? Chump.
I think you have things backward here. I am not bothered by those who
prefer tubulars. However, for those who have not used them, I
mentioned some of the reasons why most riders no longer use them. So
why do you feel compelled to call me a chump about that.
> You blow your PERCEIVED shortcomings of tubulars way out of
> proportion, and then, when I (and others) call you on it, you try to
> come up with some blustery, psuedo(heavy on the psuedo)scientific
> defense of your position, just like a child who lacks the
> self-confidence to allow that perhaps they were a bit wrong.
Let's leave the insults and get to the matter at hand. What pseudo
(or psweedo) seems to not be correct, heavy or otherwise?
> Just because YOU don't like something doesn't mean that everybody
> else HAS to feel the same way. (typical kindergarten lesson
> provided as a public service announcement for Jobst, who must've
> missed that day of class)
I like tubulars just fine, but not for general road riding. I find them
tedious to maintain and I don't like their thermal characteristics on
steep roads.
Jobst Brandt <jbr...@hpl.hp.com>
Sean Robey
BikeTires <bike...@aol.com> wrote in article
<19980316231...@ladder03.news.aol.com>...
> As stated previously a purely personal response in no way associated with
the
> attached E-mail address.
>
> My response is very simple, you often submit very positive and useful
> information, however you are also the king of flame based on your own
opinions
On the contrary, Jobst (and a few others) base their flames on the
frustrating regularity with which others present loose observation (even if
it is over the course of years) as evidence of some physical phenomenon.
>As with anything in any industry a person can make a graph,
> schematic, report, etc. state just about anything you want it to state.
Sure you can make statistics lie, but I have been reading these newsgroups
for years, and I have never known Jobst to make any statements of fact
without providing the physical reasoning behind it. Those who understand
the science involved will debate with or without flames, those who don't
can take their chances with the flames, or shut up & try to learn
something.
> To hack back at a Professional Retailer or a consumer purely because it
doesn't
> meet your idea of the correct is arrogant
I'm a 'Profesional Retailer' and Jobst's assistance has enabled me to prove
(not just to spout recycled folklore) to my customers that there is no
rolling resistance advantage to tubulars over clinchers. And what's wrong
with arrogance, it's just a word. Is it conceit or dignity? Authority or
aggression? Knowledge or presumption?
>In my own opinion you are much better at and more
> qualified than I am in blurting "ad hominem" responses, mainly because I
> couldn't find your quoted term in any dictionary.
Pretentious is also just a word, but it made me buy the Shorter Oxford.
Check it out, your dictionary is not serving you well.
> A tremendous number of cyclists and potential cyclists read the numerous
posts on the
> newsgroups daily. You could actually add a tremendous amount of
information,
> however you feel an incesant need to grab inate and mundane points and
turn
> them into something bigger than they truly are. For what? Who knows
only
> Jobst's mind does.
I assume you mean 'inane', but it's time for me to ask you to get specific.
What part of the debate about tubulars v clinchers do you disaggree with
and why?. The rolling resistance tests performed by Continental a while
back only serve to confirm what Jobst is saying. The only arguments put
forward against the properties of rim glue (as professed by JB) are based
on 'that never happened to me' anecdotal evidence, which although
interesting, is beside the point, because it happens to enough cyclists
that you must regard it as a real phenomenon. Perhaps you feel that in your
considerable experience (no sarcasm) tubulars have a better 'feel', they
are like 'riding on silk' etc. This kind of argument gets you only so far;
at some point it has to be measurable, not only because this is the entire
basis of science, but because without it, anyone's claims are valid. So I
say again, what false facts has JB presented to us and why is he wrong. I'm
keen to read about it .
> So publicly I say to any future cyclists reading this as well as any
person who
> chooses to read and/or respond to a Jobst Brandt post, make sure it's
really
> as big an issue as he has made it seem, get more opinions, read how
much
> flame posts he gets as opposed to anybody else who is sharing their
opnions.
> After all this entire post is just my opinion.
Tubulars v clinchers are a big issue. There are cyclists who persist in
spending more than they need to in the mistaken belief that they are
faster. If the professionals in our industry were able to say the words 'I
don't know' more often, the intelligent debate on these subjects would not
be stifled by the cacophany of babble from those who can't let go of their
folklore & accept that things are not allways what they seem to be, even if
they really truly seem to be that way.
>The bike shop and consumer decides whether these
> products work or not. We will let them decide.
One thing I have learned, and firmly believe (not so much that I can't be
convinced otherwise) is that people are very poor judges of their physical
environment. This is why myths and follore survive in our industry, and why
the consumer is the last person (except mabye for the professional cyclist)
who is capable of deciding what works and why?. Which of the following
myths do you (all of you!) subscribe to?
1. Tubulars are faster than clinchers!
2. BB axles should not be greased!
3. Steel frames become more flexible if ridden enough miles!
4. Narrower tyres have lower rolling resistance.
5. Coloured treads go faster/handle better than black ones.
There are many more & I'm not too proud (or is that arrogant) to admit that
some of them seemed reasonable to me until proved otherwise by the likes of
Jobst, who never just posts opinions without laying his reasoning on the
line for everyone to have a go at. So get stuck into him, but for the love
of God say something useful.
Bob Manson
I lurk, and I lurk, and I lurk...I'm Popeye the Sailor Lurker! I've
lurked for 12 years and I'm still goin' strong!
In article <01bd5166$c2e5dc40$7a03...@srobey.dynamite.com.au>,
Sean Robey <sro...@dynamite.com.au> wrote:
>On the contrary, Jobst (and a few others) base their flames on the
>frustrating regularity with which others present loose observation (even if
>it is over the course of years) as evidence of some physical phenomenon.
Indeed. This is very similar to the snake oil phenomenon in the home
hi-fi audio industry. People spend $2000 on magic audio cables, or buy
cork discs at $5 a piece to try and minimize "reflections", use green
marker on their CDs, or speak knowingly of "jitter" from CD
transports. I tend to avoid these sorts of audio shops, just like I
avoid similar types of nonsense from bike shops.
For a reasonably on-topic example, I'm amazed people are persistent
enough to still use tubulars for everyday riding. Nope, I haven't
tried them. Nope, I'm not going to. Yes, I ride a lot.
They're messy and inconvenient, and substantially more expensive than
a similar class of clincher. The reasonable claims made (slightly
lower rolling resistance, perhaps a lower puncture rate) wouldn't be
worth the inconvenience and cost for me. The unreasonable claims
("ride like silk") IMO are unsubstaniated nonsense, in the same
category as "steel frames ride stiffer than aluminum" or "squirrels
are madly attracted to titanium frames".
I've forever been at a loss to understand why people associate
inconvenient with better, except that it's arcane and mysterious.
("Ayep, we tie-n-solder these wooden-rim wheels...it's somethin'
got passed down down from Bluto back in the 20s...")
BikeTires <bike...@aol.com> wrote in article
<19980316231...@ladder03.news.aol.com>...
>As with anything in any industry a person can make a graph,
> schematic, report, etc. state just about anything you want it to state.
Yes, but that's not what's being discussed here. Various people are
making claims about why tubulars are better than clinchers, without
any real evidence. (Conti Grand Prix 3000 orange tires give an
incredibly "smoother" ride than the grey ones. Really! Trust me! I've
rode'm both for 5000 miles! :-)
On the other hand, it is a fact that tubulars are more inconvenient to
use than clinchers. Does anyone really think fooling around with "tub"
(*chortle*) glue is easy and convenient, compared to not having to at
all? Pre-stretching tires? Sewing them up? Yep, that's how *I* want to
spend my days...not. (Tho I suspect getting high off the glue fumes is
fun.)
I, Bozo "Muad"Bob, King of the Goofs, Ruler of the Seven Spheres of
Bamtoozla, Abuser of The Spice, speaking ex-cathedra (bow before me
and be slain, my slugs) will make a sweeping claim for the entire
known universe that for any rational being, whatever advantages
tubulars have needs to outweigh these marked disadvantages. I
certainly wouldn't list a .001% loss of rolling resistance in this
category (tho I could be persuaded this would be important in other
situations, like a TT). Perhaps others would.
Jobst generally knows what he's talking about, as he has enough smarts
to not make statements he can't back up. He's not perfect, he's not
always right (*gasp*), and I don't particularly take what he says as
gospel. On the other hand, he has a lot of experience, and backs up
his claims with verifiable facts and statements that are consistent
with other people's experiences.
If you (the collective you, yes YOU, you know who you are!) can't do
this, then your statements are meaningless for anyone else. Basic
philosophical crapola 101. (Now for my next trick, I'm going to prove
that I don't exist and disappear.)
In article <01bd5166$c2e5dc40$7a03...@srobey.dynamite.com.au>,
Sean Robey <sro...@dynamite.com.au> wrote:
>environment. This is why myths and follore survive in our industry, and why
>the consumer is the last person (except mabye for the professional cyclist)
>who is capable of deciding what works and why?.
Mmmm, this may be a bit harsh and probably not a terribly complete
explanation for the cause of the myths. I'm sure a lot of it is
because spewing arcane myths allow people to feel and sound superior
and knowledgeable. They also help sell expensive stuff to people that
really don't need it. People also tend to believe what they're told,
and ignore what they feel (which is probably what you said). ("Well,
this seat is uncomfortable, but I'm sure it's just because it needs to
break in." uh-huh...)
Taking the "green marker on CD" example from the audio industry...
it's very easy to demonstrate that this does nothing for the play
quality (well, it might *degrade* it). It's pretty much considered to
be a nonsense myth now. But people spread this around quite a bit when it
came out, and believed in it like it was the Manna From On High. People
I heard it from acted like they had some sort of sekret 33l33t inside info
that made them oh so wiser than everyone else. Many people could "hear the
difference".
The same sort of stuff passes for "high-end" bicycling in many bike
shops. Stay away! Use your noggin'! (with a helmet on it :-)
ObPlug: On the other hand, Bebop pedals r00l.
Bob
Brian Nystrom
Don Saleski wrote:
>
once you take into consideration the cost of a cheap tubular
> part of the bike (lighter rims and lighter tire-tube structure), the
> sew-ups win.
After two seasons of trouble, I gave up on cheap Clement tubulars. For a
few bucks more, you can get the Conti Giro and the difference is night
and day. Smoother, rounder and you never have to worry about the
stitching blowing out. An even better deal, if you can still find them,
the Conti Triathlons which have been on closeout at around $25. I bought
10 of them for $220.
Kenneth Lehner
> Sure you can make statistics lie, but I have been reading these newsgroups
> for years, and I have never known Jobst to make any statements of fact
> without providing the physical reasoning behind it. Those who understand
> the science involved will debate with or without flames, those who don't
> can take their chances with the flames, or shut up & try to learn
> something.
I know you said "I have never known", but I hope you'll accept my first
handobservation. Jobst once proclaimed that it is impossible to get a draft
behind
another swimmer because the leading swimmer is pushing water backwards,
thus inhibiting the forward progress of the trailing swimmer. Not only did
Jobst not understand the physics of human swimming, but he showed his
lack of practical experience in the matter. (Highest achieved human swim speed
is 5 to 6mph, due to the amount of effort required to move water out of the
way (i.e., *forward*); anyone who has ever drafted another swimmer can clearly
feel the increased speed/decreased effort of the trailing swimmer; casual
observation of a freestyle sprint will see a (literal) wall of water follow the
swimmers into the wall). Yes, this came up on wreck.bikes (I believe related
to
Jobst's "if the drafting cyclist has a burning incense stick, the leading
cyclist
won't smell it" argument against the leading cyclist benefiting from a
drafter).
On the other hand, I have learned a lot from Jobst's postings, and look forward
to reading them for the educational and entertainment value. He's just not
perfect (and doesn't claim to be, I'm sure).
Ken "not Sheldon Brown" Lehner
Propeloton
No myth or lore-just well made-custom equipped to the customer-road bikes-
-come visit...would love to talk
Peter
ProPeloton
Boulder, CO
BikeTires
>"Sean Robey" <sro...@dynamite.com.au>
>On the contrary, Jobst (and a few others) base their flames on the
>frustrating regularity with which others present loose observation
My entire point from the start was why flame? They can offer valuable
information yet still fill the need to flame their opinion in response.
>Pretentious is also just a word, but it made me buy the Shorter Oxford.
>Check it out, your dictionary is not serving you well.
I used a number of Webster dictionairies, they you for the additional source
.>What part of the debate about tubulars v clinchers do you disaggree with
>and why?.
I have never disagreed or agreed with the debates of tubulars vs clinchers on
these boards, nor do I necessarily agree or disagree with Jobst's posts. I
choose not to respond with my opinions because they are opinions and decisions
I have come to as a cyclist. I am familiar with the rolling resistance tests
completed by Continental, I have also seen them performed by Michelin,
Specialized and Vredestein as well as others the responses vary tremendously
depending on the companies completing the test.
>So I
>say again, what false facts has JB presented to us and why is he wrong.
I have never stated he was right or wrong. My response was purely based on
the manner of presentation. I am not a scientist the only "ist" is cyclist.
I still and will always believe the decision ends with the retailer and the
consumer, I feel he could offer his information in a much more valuable and
constructive manner. Taking note of course it is opinion backed by his
reasons.
> This is why myths and follore survive in our industry, and why
>the consumer is the last person (except mabye for the professional cyclist)
>who is capable of deciding what works and why?
I don't agree with this statement. The world is not filled with only
professional cyclists, A tire that works for one may not work for others, it
is the opportunity to have choice based on needs. There were 45 million tires
imported to the U.S. in 1996 to provide that choice to the consumer. In my
belief cycling is tremendously mental also, if you feel it is right and it
works then go with it, if you find something better then go with that. To
what degree should "Science" be applied in tires? Not for me to decide,
however I do feel there is a bit of overkill here. A tire producer in the
interest of selling tires, develops their products to fit the world market.
To me, the Retailer and Consumer decides, hopefully if they are reading here
they can get additional information to assist them in their choice.
>Which of the following
>myths do you (all of you!) subscribe to?
>1. Tubulars are faster than clinchers!
>2. BB axles should not be greased!
>3. Steel frames become more flexible if ridden enough miles!
>4. Narrower tyres have lower rolling resistance.
>5. Coloured treads go faster/handle better than black ones.
You call them myths, I call them choices.
Thank you for your post and opinions,
Best regards
Mike Sullivan
John Joseph Taglia
Bob Manson wrote (among other things):
The unreasonable claims ("ride like silk") IMO are unsubstaniated
nonsense, in the same category as "steel frames ride stiffer than
aluminum" or "squirrels are madly attracted to titanium frames".
Squirrels are attracted to titanium frames--look at who buys titatnium
frames. (That's a joke folks. ;-> )
>
Jeffrey J. Potoff
BC Holicky wrote:
<snip>
> This is a riot. Now you're telling me that I'm hearing things. You
> start off by saying that I need to be more scientific in my 'defense' of
> tubulars and then you finish off your misguided diatribe by saying that I
> like tubs better because, perhaps, they SOUND better?!?! Jobst, you are
> a fool, and when you come up with something like this it makes that all
> too obvious to the rest of us. I never once said that I like tubs
> because they are faster. I don't give two hoots whether the glue of a
> tub rim absorbs more energy than a clincher or vise versa. I said they
> FEEL better to ME. Does that threathen you somehow? Chump.
Bruce,
The tone of your post and the name calling don't exactly
boost your credibility. Perhaps if you stuck to facts and didn't
take everything as a personal insult you could come up with a
more convincing arguement.
Jeff
tku...@diabloresearch.com
In article <6elbuc$l...@enews1.newsguy.com>,
man...@newsguy.com (Bob Manson) wrote:
>
> For a reasonably on-topic example, I'm amazed people are persistent
> enough to still use tubulars for everyday riding. Nope, I haven't
> tried them. Nope, I'm not going to. Yes, I ride a lot.
Let me tell you something about tubulars. ANYONE can tell a tubular
ride from a clincher ride. They ride better, hands down and no
contest. So what? Clinchers ride OK and some of the better one's
approach a tubular ride crab style. Your speed isn't limited by
your ride comfort so it doesn't count up there for racers. My guess
is that the fact that a tubular is a round tire and a clincher is
U-shaped is the cause for the immediately detectable ride difference,
but it is there and even a klutz can tell.
When you are riding around like we normal rec riders do, the chances
are that you will get a flat from a snake bite, a thorn or a piece
of glass. Sometimes it's from a Michelin wire as Jobst calls them.
They are pieces of wire from steel belted tires, maybe 30 gauge, small
and hard to see in a tire.
In the case of a snake bite -- it is possible to snake bite tubulars but
it doesn't happen often with good tubulars. You can therefore run lower
and still more comfortable pressure.
The rest of the flats are caused by a piece of something in the tire and
I've found that with my progressively poorer sight it becomes harder and
harder to find the foul demon sucking flat causer. When you replace a
tubular you are also replacing the tire at the same time. You start without
something stuck in your tire that is about to flat your new tube. So you
don't get four flats in a row until you find that stupid thorn. OK so
I make the occasional mistake and don't find the right piece of glass.
Yet with good clincher tires you can usually go for a year without a
flat. I've done it often enough that I have dried glue in my flat repair
kits, my two good tubes have holes worn in them from the seat pack and
my pump washer is dried out.
There are plenty of good reasons to ride tubulars and plenty of good
reasons not to ride them. You pays your money and you takes your choice.
-----== Posted via Deja News, The Leader in Internet Discussion ==-----
http://www.dejanews.com/ Now offering spam-free web-based newsreading
Jobst Brandt
Kenneth Lehner writes:
> Jobst once proclaimed that it is impossible to get a draft behind
> another swimmer because the leading swimmer is pushing water
> backwards, thus inhibiting the forward progress of the trailing
> swimmer. Not only did Jobst not understand the physics of human
> swimming, but he showed his lack of practical experience in the
> matter.
I think you confuse surface waves with currents in water. The swimmer
moves forward in a medium getting no reaction from outside the medium
(such as pushing off from a fixed object). The only means of
propulsion is kinetic reaction. Since the volume of water displaced
does not end up at the destination, but flows around the body, it has
a rearward velocity as it passes the swimmer and the swimmer must
accelerate water rearward to overcome viscous losses. Therefore,
there must be a net rearward flow after the passing of a self
propelled body.
This is the only claim I made with respect to this discussion.
> (Highest achieved human swim speed is 5 to 6mph, due to the amount
> of effort required to move water out of the way (i.e., *forward*);
> anyone who has ever drafted another swimmer can clearly feel the
> increased speed/decreased effort of the trailing swimmer; casual
> observation of a freestyle sprint will see a (literal) wall of water
> follow the swimmers into the wall).
How do you reconcile this with propulsion in a fluid medium. I also
pointed out that birds don't draft one another for the same reason.
They fly in an echelon or double echelon V-formation, avoiding the
turbulence and backwash of the leading bird. In fact this was the
topic that gave rise to the swimming pool example.
> Yes, this came up on wreck.bikes (I believe related to Jobst's "if
> the drafting cyclist has a burning incense stick, the leading
> cyclist won't smell it" argument against the leading cyclist
> benefiting from a drafter).
The incense example was brought as evidence that there is no
circulation between the riders and that this is essentially
incompressible flow around the bodies. The claim was that the front
rider benefits from the following rider in a pace line. My
contention was that the benefit was on the order of sound waves and
that this could be seen by hanging a piece of Styrofoam from a thread
to observe how close a 25mph rider approached before this pendulum was
displaced.
The results of this discussion ended with subjective arguments similar
to silk smooth tubulars.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Tom Kunich writes:
> Let me tell you something about tubulars. ANYONE can tell a tubular
> ride from a clincher ride. They ride better, hands down and no
> contest. So what? Clinchers ride OK and some of the better one's
> approach a tubular ride crab style. Your speed isn't limited by
> your ride comfort so it doesn't count up there for racers. My guess
> is that the fact that a tubular is a round tire and a clincher is
> U-shaped is the cause for the immediately detectable ride difference,
> but it is there and even a klutz can tell.
You may have missed the earlier discussion on this subject, but coming
from dejanews you should have caught it, they having complete
archives. Your testimonial without any substantiating evidence or
reason falls in the cracks of anecdotal lore. The rigidity of a tire
casing and its damping or rolling losses are well documented and from
several sources. I have posted the rolling resistance tests done by
IRC and I appear in an add in which I am cornering on clinchers at a
lean angle most riders would not attempt with any tire. This in an
effort to dispel the myths of the tubular's superior cornering.
Both tubulars and clinchers are completely round in cross section in
the portion free of the rim. There is no way of causing any other
shape with a uniform bias ply casing. The flexibility of the casing
is so low that the tread stiffness is the governing structure.
Therefore, tires like the Avocet TT, which is based on the Criterium
but with a thinner tread, has the lowest RR and is the most tubular
like of these tires. If it were fitted with a thin walled tube it
would not only be better than a glued on tubular that it already is,
but it would beat a tubular with hard glue. The tube, being pressed
against the casing, acts like a tread on the inside of the tire and
causes RR losses.
> When you are riding around like we normal rec riders do, the chances
> are that you will get a flat from a snake bite, a thorn or a piece
> of glass. Sometimes it's from a Michelin wire as Jobst calls them.
> They are pieces of wire from steel belted tires, maybe 30 gauge, small
> and hard to see in a tire.
Penetrations into a tire are dependent on the thickness of material
from outside to air chamber, if the sharp object enters the tire at
all. In that department, tubulars, with their thin tread and tube,
more vulnerable than clinchers, Kevlar bands making little difference
especially for thorns and Michelin wires, but also for slivers of
glass that cleave between cords. One of the reasons tubulars never
have much tread is that it would be useless because a road tire casing
usually fails before the tread wears out.
> In the case of a snake bite -- it is possible to snake bite tubulars
> but it doesn't happen often with good tubulars. You can therefore
> run lower and still more comfortable pressure.
You didn't say why. I don't understand how you can present such
unsupported claims after the exchanges that have been made here. The
only reason tubulars have traditionally gotten fewer snake bites is
from the days when they were all equipped with latex tubes. Latex has
several times the stretch of an equivalent butyl tube and since these
punctures are compression wounds that fail because the lateral stretch
of the rubber has been exceeded by the compression, latex is more
resistant.
Rubber is an incompressible elastic material that stretches away from
a compression between two surfaces as it squishes out of the gap.
This stretch is what causes failure, not a cutting action.
> There are plenty of good reasons to ride tubulars and plenty of good
> reasons not to ride them. You pays your money and you takes your choice.
I don't think you mentioned a major problem with tubulars that I offer
from an anonymous poster on wreck.bike.racing:
: Does anyone know of a place to send your tubulars for repair? A
: couple years ago I sent a Sprinter to Nelo Breda in Texas. He did a
: great job for about $12 or $15. But he doesn't have an ad in the
: current Velo News. Is there anyone else someone can recommend?
Jobst Brandt <jbr...@hpl.hp.com>
Adam Rice
In article <6en27o$3...@hplntx.hpl.hp.com>, jbr...@hpl.hp.com (Jobst
Brandt) wrote:
> You may have missed the earlier discussion on this subject, but coming
> from dejanews you should have caught it, they having complete
> archives. Your testimonial without any substantiating evidence or
> reason falls in the cracks of anecdotal lore. The rigidity of a tire
> casing and its damping or rolling losses are well documented and from
> several sources. I have posted the rolling resistance tests done by
> IRC and I appear in an add in which I am cornering on clinchers at a
> lean angle most riders would not attempt with any tire. This in an
> effort to dispel the myths of the tubular's superior cornering.
Aren't there any objective, measurable factors other than rolling
resistance that come into play with tires?
[snip]
> I don't think you mentioned a major problem with tubulars that I offer
> from an anonymous poster on wreck.bike.racing:
>
> : Does anyone know of a place to send your tubulars for repair? A
> : couple years ago I sent a Sprinter to Nelo Breda in Texas. He did a
> : great job for about $12 or $15. But he doesn't have an ad in the
> : current Velo News. Is there anyone else someone can recommend?
As far as I know, Nelo does still patch tubulars.
GBSHAUN
> The claim was that the front<BR>
>rider benefits from the following rider in a pace line. My<BR>
>contention was that the benefit was on the order of sound waves and<BR>
>that this could be seen by hanging a piece of Styrofoam from a thread<BR>
>to observe how close a 25mph rider approached before this pendulum was<BR>
>displaced.<BR>
><BR>
>The results of this discussion ended with subjective arguments similar<BR>
>to silk smooth tubulars.<BR>
><BR>
>Jobst Brandt <jbr...@hpl.hp.com> <BR>
><BR>
The German national team has done a lot of work over the past few years with
SRM cranks. I know one thing they learned was how, because of this effect, a
rider in a team pursuit needed to produce more power when in 4th position
than when in 3rd.
SW
David Rees
The problem with some of Jobst's refutations of widely-accepted, but
non-empirical 'evidence' is that his engineering-based calculations are far
too simple for the complex forces that a given piece of equipment will see.
As an example, many engineering types like to say that an OS Al frame
(Cannondale, eg), does not transfer (perceptibly) more shock to the rider
as compared to a Ti frame. They look at a simple, vertically-loaded Warren
truss, but this is a specious argument, as loads are never vertical, as
there is all sorts of weird twisty stuff going on in all the other
components at the same time. That experienced, scientifically-trained
riders can feel a difference between two otherwise identical bikes (same
geometry, components, SAME -not similar- wheels, but different-section and
material tubes) shows the limitations of their analysis of what's REALLY
happening. Quantification of the forces acting upon a bicycle would bring a
Cray to it's knees, so don't look to Jobst for a definitive analysis of
every cycling-related phenomenon. This is not meant as a flame, as Jobst is
extremely knowledgeable, but there are times when he says he knows when he
should more correctly say "I don't know".
Jobst Brandt
G B Shaun writes:
>> The claim was that the front rider benefits from the following
>> rider in a pace line. My contention was that the benefit was on
>> the order of sound waves and that this could be seen by hanging a
>> piece of Styrofoam from a thread to observe how close a 25mph rider
>> approached before this pendulum was displaced.
>>
>> The results of this discussion ended with subjective arguments similar
>> to silk smooth tubulars.
> The German national team has done a lot of work over the past few
> years with SRM cranks. I know one thing they learned was how,
> because of this effect, a rider in a team pursuit needed to produce
> more power when in 4th position than when in 3rd.
I think that requires a bit more evidence than such a general claim.
I think most riders who have ridden in a pack feel that the ride gets
easier the farther back they are in the pack. Besides, the spectators
also have this perception, because they can feel the draft as the
breakaway of two or four riders goes by and then the storm as the ten
man chase group goes by. I would like to see some data or technical
description of the effect. Why in particular the third man and not
the second, and what can be said of the fourth of five or the fifth of
six? This opens a whole new can of worms.
Often in these discussions, tangential and more complex issues are
brought in to dodge the initial issue. I think we are approaching
such a point.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
David Rees diverges with:
This essay contains no data or references at all, nor does it have any
thermal effects on tubulars, but probably offers a good starting point
to jump to other even broader subjects. We could get to more global
and less definable problems on which we expound upon qualitatively,
like the effect of green marker on the edge of time trial tires in
contrast to green marker on CD's about which I know little, having
never tried either.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Adam Rice writes:
> Aren't there any objective, measurable factors other than rolling
> resistance that come into play with tires?
Wear durability, casing resistance to chafing and rupture, maximum
lean angle wet and dry,maximum safe operating pressure, ease of
installation, ease of repairing flats...
What are you getting at? These things have all been discussed here.
>> I don't think you mentioned a major problem with tubulars that I
>> offer from an anonymous poster on wreck.bike.racing:
>>: Does anyone know of a place to send your tubulars for repair? A
>>: couple years ago I sent a Sprinter to Nelo Breda in Texas. He did
>>: a great job for about $12 or $15. But he doesn't have an ad in
>>: the current Velo News. Is there anyone else someone can recommend?
> As far as I know, Nelo does still patch tubulars.
I find $12 to $15 plus shipping and lost time an unreasonable
alternative to sticking a patch on a tube.
Jobst Brandt <jbr...@hpl.hp.com>
Jeffrey J. Potoff
David Rees wrote:
>
> The problem with some of Jobst's refutations of widely-accepted, but
> non-empirical 'evidence' is that his engineering-based calculations are far
> too simple for the complex forces that a given piece of equipment will see.
> As an example, many engineering types like to say that an OS Al frame
> (Cannondale, eg), does not transfer (perceptibly) more shock to the rider
> as compared to a Ti frame. They look at a simple, vertically-loaded Warren
> truss, but this is a specious argument, as loads are never vertical, as
> there is all sorts of weird twisty stuff going on in all the other
> components at the same time. That experienced, scientifically-trained
> riders can feel a difference between two otherwise identical bikes (same
> geometry, components, SAME -not similar- wheels, but different-section and
> material tubes) shows the limitations of their analysis of what's REALLY
> happening. Quantification of the forces acting upon a bicycle would bring a
> Cray to it's knees, so don't look to Jobst for a definitive analysis of
> every cycling-related phenomenon. This is not meant as a flame, as Jobst is
> extremely knowledgeable, but there are times when he says he knows when he
> should more correctly say "I don't know".
With this kind of mindset one has to wonder how we ever landed a
spacecraft on the moon. You seem to think that because something
appears complex we should all throw up our hands and proclaim
it can't be done. Or is it possibly that because you don't understand
the phenomena at work you proclaim that the problem can't be solved ?
BTW - 'Bringing a Cray to its knees' doesn't mean much these days. I
can
put Cray computering power on my desk for around $6000. The
computational power
is most certainly availible to solve these problems.
Jeff
GBSHAUN
Jobst writes:
><BR>
>G B Shaun writes:<BR>
><BR>
>>> The claim was that the front rider benefits from the following<BR>
>>> rider in a pace line. My contention was that the benefit was on<BR>
>>> the order of sound waves and that this could be seen by hanging a<BR>
>>> piece of Styrofoam from a thread to observe how close a 25mph rider<BR>
>>> approached before this pendulum was displaced.<BR>
>>> <BR>
>>> The results of this discussion ended with subjective arguments similar<BR>
>>> to silk smooth tubulars.<BR>
><BR>
>> The German national team has done a lot of work over the past few<BR>
>> years with SRM cranks. I know one thing they learned was how,<BR>
>> because of this effect, a rider in a team pursuit needed to produce<BR>
>> more power when in 4th position than when in 3rd.<BR>
><BR>
>I think most riders who have ridden in a pack feel that the ride gets<BR>
>easier the farther back they are in the pack. Besides, the spectators<BR>
>also have this perception, because they can feel the draft as the<BR>
>breakaway of two or four riders goes by and then the storm as the ten<BR>
>man chase group goes by.
I don't think you read what I wrote: I didn't say anything about rider or
spectator perception, this was from SRM data (Power produced at the pedals).
EACH rider, aparently, produced less power when in 3rd spot than when in 4th
(last), so clearly it wasn't caused by a drop in speed. I also very much doubt
that their positions all became more aerodynamic as they moved up.
>I think that requires a bit more evidence than such a general claim.<BR>
Sorry, next time I won't share these pieces of information that I've been
lucky enough to be in a position to receive unless I have all the raw and fully
analyzed data, backed up naturally with a second independent study.
Might be a small r.b.tech in future.
> Why in particular the third man and not<BR>
>the second, and what can be said of the fourth of five or the fifth of<BR>
>six? This opens a whole new can of worms.<BR>
><BR>
>Often in these discussions, tangential and more complex issues are<BR>
>brought in to dodge the initial issue. I think we are approaching<BR>
>such a point.<BR>
><BR>
>Jobst Brandt <jbr...@hpl.hp.com> <BR>
Team pursuits only have four riders.
I would expect that when in second place the power necessary would increase as
there is less draft, and I very much doubt there is any further reduction in
drag from having a second person behind.
SW
Jobst Brandt
G B Shaun writes:
>>> The German national team has done a lot of work over the past few
>>> years with SRM cranks. I know one thing they learned was how,
>>> because of this effect, a rider in a team pursuit needed to
>>> produce more power when in 4th position than when in 3rd.
>> I think most riders who have ridden in a pack feel that the ride
>> gets easier the farther back they are in the pack. Besides, the
>> spectators also have this perception, because they can feel the
>> draft as the breakaway of two or four riders goes by and then the
>> storm as the ten man chase group goes by.
> I don't think you read what I wrote: I didn't say anything about
> rider or spectator perception, this was from SRM data (Power
> produced at the pedals). EACH rider, apparently, produced less
> power when in 3rd spot than when in 4th (last), so clearly it wasn't
> caused by a drop in speed. I also very much doubt that their
> positions all became more aerodynamic as they moved up.
If I were to say that the Italian national TTT noticed that power
dropped in roughly a 1/X function to the rear with an asymptote of 2/3
power, what would you respond? What I said, is that such a statement
dangles in the breeze with no citation of source and is no better than
most of the other claims of, for instance, frames getting soft.
>> I think that requires a bit more evidence than such a general claim.
> Sorry, next time I won't share these pieces of information that I've
> been lucky enough to be in a position to receive unless I have all
> the raw and fully analyzed data, backed up naturally with a second
> independent study. Might be a small r.b.tech in future.
If you don't play according to my rules, I'll take my toys and leave!
I guess that settles the tubular question.
>> Why in particular the third man and not the second, and what can be
>> said of the fourth of five or the fifth of six? This opens a whole
>> new can of worms.
>> Often in these discussions, tangential and more complex issues are
>> brought in to dodge the initial issue. I think we are approaching
>> such a point.
> Team pursuits only have four riders. I would expect that when in
> second place the power necessary would increase as there is less
> draft, and I very much doubt there is any further reduction in drag
> from having a second person behind.
I don't think you'll get many takers for that speculation, and it
does not explain the third man theme that you propose.
Jobst Brandt <jbr...@hpl.hp.com>
Brad Anders
jbr...@hpl.hp.com (Jobst Brandt) writes:
>G B Shaun writes:
>>>> The German national team has done a lot of work over the past few
>>>> years with SRM cranks. I know one thing they learned was how,
>>>> because of this effect, a rider in a team pursuit needed to
>>>> produce more power when in 4th position than when in 3rd.
>>> I think most riders who have ridden in a pack feel that the ride
>>> gets easier the farther back they are in the pack. Besides, the
>>> spectators also have this perception, because they can feel the
>>> draft as the breakaway of two or four riders goes by and then the
>>> storm as the ten man chase group goes by.
>> I don't think you read what I wrote: I didn't say anything about
>> rider or spectator perception, this was from SRM data (Power
>> produced at the pedals). EACH rider, apparently, produced less
>> power when in 3rd spot than when in 4th (last), so clearly it wasn't
>> caused by a drop in speed. I also very much doubt that their
>> positions all became more aerodynamic as they moved up.
I think there may be another explanation for this increase in power.
I have not seen the article, so I do not know the test conditions nor
do I know the magnitude of the power differential for the fourth rider.
When a rider in a pursuit drops back to position four, they do so by
taking a longer path AND by slowing down. To keep with the group they
must accelerate.
Have any of you actually seen raw SRM data? I have had the chance to
work with it, and it is very noisy due to the time-varying power output
of humans. Smoothing is required. I would conjecture that the power
differential for the fourth rider is based on an average reading of the
interval, and the reading is higher because the initial acceleration after
getting back on is causing the offset.
>> Sorry, next time I won't share these pieces of information that I've
>> been lucky enough to be in a position to receive unless I have all
>> the raw and fully analyzed data, backed up naturally with a second
>> independent study. Might be a small r.b.tech in future.
No need to get huffy. It is the nature of scientific and engineering study
to challenge data. Accepting data without verification often leads to
incorrect conclusions.
--
******************************
* Brad Anders / Phoenix, AZ *
* ban...@netcom.com *
******************************
John Serafin
I think that the general claim made by G B Shaun is that the last position
works harder than the next to last.
I suspect that we are expected to know that team pursuit means teams of
four, just as some believe that cyclist means "licensed bicycle racer".
Did any one else think that a claim was made that rider 4 works harder
than rider 3 in a line longer than 4? I didn't, and I get trapped by
almost any ambiguity.
jbr...@hpl.hp.com (Jobst Brandt) writes:
>G B Shaun writes:
>>> The claim was that the front rider benefits from the following
>>> rider in a pace line. My contention was that the benefit was on
>>> the order of sound waves and that this could be seen by hanging a
>>> piece of Styrofoam from a thread to observe how close a 25mph rider
>>> approached before this pendulum was displaced.
>>>
>>> The results of this discussion ended with subjective arguments similar
>>> to silk smooth tubulars.
>> The German national team has done a lot of work over the past few
>> years with SRM cranks. I know one thing they learned was how,
>> because of this effect, a rider in a team pursuit needed to produce
>> more power when in 4th position than when in 3rd.
>I think that requires a bit more evidence than such a general claim.
>I think most riders who have ridden in a pack feel that the ride gets
>easier the farther back they are in the pack. Besides, the spectators
>also have this perception, because they can feel the draft as the
>breakaway of two or four riders goes by and then the storm as the ten
>man chase group goes by. I would like to see some data or technical
>description of the effect. Why in particular the third man and not
>the second, and what can be said of the fourth of five or the fifth of
>six? This opens a whole new can of worms.
>Often in these discussions, tangential and more complex issues are
>brought in to dodge the initial issue. I think we are approaching
>such a point.
>Jobst Brandt <jbr...@hpl.hp.com>
--
John P. Serafin | Operating a bicycle is more like driving than riding.
jps at pobox com | Operating an automobile is more like riding than driving.
GBSHAUN
> this was from SRM data (Power<BR>
>>> produced at the pedals). EACH rider, apparently, produced less<BR>
>>> power when in 3rd spot than when in 4th (last), so clearly it wasn't<BR>
>>> caused by a drop in speed. I also very much doubt that their<BR>
>>> positions all became more aerodynamic as they moved up.<BR>
><BR>
>I think there may be another explanation for this increase in power. <BR>
>I have not seen the article, so I do not know the test conditions nor<BR>
>do I know the magnitude of the power differential for the fourth rider.<BR>
>When a rider in a pursuit drops back to position four, they do so by<BR>
>taking a longer path AND by slowing down. To keep with the group they<BR>
>must accelerate. <BR>
><BR>
>Have any of you actually seen raw SRM data? I have had the chance to <BR>
>work with it, and it is very noisy due to the time-varying power output<BR>
>of humans. Smoothing is required. I would conjecture that the power <BR>
>differential for the fourth rider is based on an average reading of the<BR>
>interval, and the reading is higher because the initial acceleration
>getting back on is causing the offset. <BR>
><BR>
I did think of that at the time and asked about it, but aparently that wasn't
it. This, by the way, was the German Olympic team preparing for Atlanta,
working in conjunction with the people who make the SRM.
I don't know the magnitude of the power difference, it was described to me as
"quite noticeable" - which depends of course upon how precise the SRM cranks
were.
I know there are 2 SRM models sold (different degrees of accuracy), and I
have heard that there is also a special, even more accurate version that they
use, but isn't generally available, - not sure about that, maybe someone knows?
SW
SW
BikeTires
Hello Jobst,
>I have posted the rolling resistance tests done by
>IRC
I'm sorry but I am not familiar with these tests, is it possible to repost
them? Where were they performed? Whose facilites were used? What tires were
they tested against. And when were they performed? Curiosity.
>Both tubulars and clinchers are completely round in cross section in
>the portion free of the rim. There is no way of causing any other
>shape with a uniform bias ply casing.
I'm not sure if I understand this, if a portion of the clincher is mounted
inside the rim, and a portion of a tubular is mounted on the rim, then where
is the cross section measured and I assume when you say round you mean
"literally" round as in an equal distance as measured at all points of the
inside and outside of the tire when inflated and with no weight applied.
> Avocet TT, which is based on the Criterium
Are these tires made by CST or National? This is not a knock, just couldn't
find one to check myself.
>Therefore, tires like the Avocet TT, which is based on the Criterium
>but with a thinner tread, has the lowest RR and is the most tubular
>like of these tires. If it were fitted with a thin walled tube it
>would not only be better than a glued on tubular that it already is,
>but it would beat a tubular with hard glue.
What other tires are "like" the Avocet TT in your opinion?
What is tubular like?
You feel they would be better because the tubular is glued to the rim while the
clincher is not. I'm more curious than anything, Isn't the tube pressed
against the casing in both instances? What actually causes the loss of R.R.
in this interpretation?
Regards,
Mike Sullivan
Brad Anders
gbs...@aol.com (GBSHAUN) writes:
>I did think of that at the time and asked about it, but aparently that wasn't
>it. This, by the way, was the German Olympic team preparing for Atlanta,
>working in conjunction with the people who make the SRM.
>I don't know the magnitude of the power difference, it was described to me as
>"quite noticeable" - which depends of course upon how precise the SRM cranks
>were.
Was any of this published? What you have here isn't very specific. I'm
questioning it because I've seen an amazing amount of poor data regarding
power output. See below for what I mean...
>I know there are 2 SRM models sold (different degrees of accuracy), and I
>have heard that there is also a special, even more accurate version that they
>use, but isn't generally available, - not sure about that, maybe someone knows?
There are three SRM models. The major difference between the models is
how many strain gauges there are, with the most expensive model having 20.
I believe SRM claims that the 20 sensor model is accurate to within +/-2 W.
But you have to see the data to understand what the problem really is.
Human power output is not constant. Numerous studies have shown that
despite what riders think, they do not pull up significantly on the
back part of the pedal stroke, and the top and bottom of the pedal stroke
are essentially dead zones. Power output for a rider in the flat going
at a constant speed looks somewhat like an epicycloid, with the minimum
output being somewhat above zero. Averages need to be taken over at least
10-20 rotations to be of any significance if you are comparing small
differences (less than 10 to 15 W). At 100 rpm, this is 6 to 12 seconds,
which at 50 kph is 83 toi 166 meters, which is on the order of about a
1/2 lap turn at a position. Unless the results were done at a steady
state for distances of over 300 meters or so, I would discount any
difference of less than 15 W, even when using the 20 strain guage version
of the SRM.
Additionally, even mild acceleration produces significant variation in
output, on the order of 50 to 100 W. When you factor this into the
measurement of a team pursuit, it makes comparison of the fourth
rider's output even more difficult, as there is an unavoidable need to
accelerate once a rider has gotten back on. Another factor is that the
rider who has just done their turn is considerably more lactic than the
other riders, and numerous studies have shown that efficiency and
coordination are poorer as lactate levels increase. It may be that part
of the power difference is due to a more choppy pedal stroke that gets
better as peak lactate levels drop.
Because of the factors I list above, I don't think that depending on
SRM readings from a set of riders doing a team pursuit is the best
way to assess differences in aerodynamic drag as a function of how
many riders are in a line and where they are placed. A wind tunnel or
a controlled experiment would be better.
Jobst Brandt
Mike Sullivan writes:
>> I have posted the rolling resistance tests done by IRC
> I'm sorry but I am not familiar with these tests, is it possible to
> repost them? Where were they performed? Whose facilities were used?
> What tires were they tested against. And when were they performed?
> Curiosity.
You can have the data, but I should explain what it shows. This
information is contained on the data sheet but may not be obvious.
The tires were mounted on the same rim with the tube offered for that
tire by the manufacturer. Tubulars (2) were glued onto the rim with
standard practice using tubular glue.
All tires were run against a smooth steel drum with the same load
at a range of inflation pressures. What is shown by fitting a power
curve to the points is that the data is consistent with little scatter,
and that all tires fit into a family of rolling resistance curves that do
not cross and are essentially the same equation. The exception was the
tubular tires that were offset by a constant from their proper curve
so that they crossed other tires.
This constant offset was causes by rim glue losses that depend on load
alone and are not affected by inflation pressure. Therefore, tires
with low rolling resistance don't get much better the harder they are
inflated and have a flatter characteristic over the range of inflation
pressures while high rolling resistance tires have a steeper slope,
getting better the less they flex but never as good as a low RR tire
except toward infinite pressure where none would have any flex or RR.
Of course these tires all had smooth or nearly smooth tread patterns.
>> Both tubulars and clinchers are completely round in cross section in
>> the portion free of the rim. There is no way of causing any other
>> shape with a uniform bias ply casing.
> I'm not sure if I understand this, if a portion of the clincher is
> mounted inside the rim, and a portion of a tubular is mounted on the
> rim, then where is the cross section measured and I assume when you
> say round you mean "literally" round as in an equal distance as
> measured at all points of the inside and outside of the tire when
> inflated and with no weight applied.
The casing is a thin walled fabric that supports the tensile stress of
containing the inflation pressure. THis casing is circular in cross
section wherever it is not in contact with the rim for both tubulars
and clinchers. Where the tire is in contact with the rim, it has no
effect on tire compliance of supporting a wheel load. Therefore, that
open face of the clincher as the underbelly of the tubular have no
effect on tire deflection.
>> Avocet TT, which is based on the Criterium
> Are these tires made by CST or National? This is not a knock, just
> couldn't find one to check myself.
Avocet tires are made by IRC.
>> Therefore, tires like the Avocet TT, which is based on the Criterium
>> but with a thinner tread, has the lowest RR and is the most tubular
>> like of these tires. If it were fitted with a thin walled tube it
>> would not only be better than a glued on tubular that it already is,
>> but it would beat a tubular with hard glue.
Rolling resistance is casued by rubber deformation losses in the
tread, the tube and the casing. The tube is firmly attached to the
casing by inflation pressure so it is like a tread inside the tire.
The whole tire flexes in three dimensional space, X, Y and Z. You can
verify this typically by laying a stadard business card between tire
and tube. It will shred to fine confetti when ridden. It is this
motion that causes hysteretic loss in the elastomer in the casing, the
tread and the tube. If the tire has patterned tread, such as a knobby
tire has in the extreme, deformation of the tread into the voids will
cause additional loss. That is why knobby tires roill so poorly.
Unfortunately, I cannot locate the tire test with that included the
Vittoria CX and Clement Criterium tires. These must be in the Avocet
archives. As you see these tests were done 12 years ago and the
following is only one of the series of tests that were performed.
Others tested the effect of various tubes in the same tires. I only
have this sample now the rest must be on some backup tapes floating
around here.
Jobst Brandt <jbr...@hpl.hp.com>
------------------------------------------------------------------------
Tires, AVOCET and SPECIALIZED, 18 Apr 86
Rolling resistance (g) vs. inflation pressure (kg/cm2) @ 50 kg load
Tire ID Size Sample Nominal wt Measured wt Width +-0.2 TPI
------- ---- ------ ---------- ----------- ----------- ---
Col 1 - Air Pressure (kg/cm2)
Col 2 - S Turbo/LR 700x25C (A) 205 234 21.4 116
Col 3 - S Turbo/LR 700x25C (B)
Col 4 - S Turbo/LS 700x25C (A) 205 243 21.4 106
Col 5 - S Turbo/LS 700x25C (B)
Col 6 - A Criterium/20 700x25C (A) 225 236 23.1 66
Col 7 - A Criterium/20 700x25C (B)
Col 8 - A Timetrial/20 700x20C (A) 215 214 21.0 116
Col 9 - A Timetrial/20 700x20C (B)
Col 10 - S Turbo/LR 700x28C (A) 225 291 24.9 66
Col 11 - S Turbo/LR 700x28C (B)
Col 12 - S Turbo/LS 700X28C (A) 225 299 24.9 66
Col 13 - S Turbo/LS 700X28C (B)
Col 14 - A Road/20 700x28C (A) 265 272 25.2 66
Col 15 - A Road/20 700x28C (B)
Col 16 - S Turbo/R 700x25C (A) 180 188 21.0 116
Col 17 - S Turbo/R 700x25C (B)
Col 18 - S Turbo/S 700x25C (A) 180 193 21.0 116
Col 19 - S Turbo/S 700x25C (B)
Col 20 - A Criterium/30 700x25C (A) 190 182 22.6 66
Col 21 - A Criterium/30 700x25C (B)
Col 22 - A Timetrial/30 700x20C (A) 165 168 20.2 106
Col 23 - A Timetrial/30 700x20C (B)
Col 24 - S Turbo/R 700x28C (A) 220 248 24.8 66
Col 25 - S Turbo/R 700x28C (B)
Col 26 - S Turbo/S 700x28C (A) 220 253 24.8 66
Col 27 - S Turbo/S 700x28C (B)
Col 28 - A Road/30 700x28C (A) 230 241 25.0 66
Col 29 - A Road/30 700x28C (B)
c1 c2 c3 c4 c5 c6 c7 c8 c9 c10 c11 c12 c13 c14 c15 c16 c17 c18 c19 c20 c21 c22 c23 c24 c25 c26 c27 c28 c29
3.5 356 365 395 369 367 392 348 347 430 443 423 432 423 406 355 364 382 386 378 387 361 369 419 432 427 442 394 403
4.0 322 329 360 343 337 361 319 316 393 401 391 393 386 376 325 333 352 356 350 357 325 331 390 390 395 401 360 363
4.5 298 302 330 319 316 336 296 290 366 373 362 368 354 347 297 309 326 332 322 329 301 302 364 362 369 375 334 331
5.0 279 282 311 298 294 314 280 271 341 348 335 345 335 320 275 289 311 311 302 307 282 284 340 339 342 351 311 310
5.5 265 268 293 287 279 297 265 255 324 329 319 327 319 305 262 276 295 296 284 295 268 267 320 322 325 333 290 289
6.0 255 253 282 274 267 282 249 242 310 312 306 310 303 293 248 260 283 285 269 281 253 252 305 304 311 318 275 273
6.5 244 242 274 264 254 269 239 230 297 294 292 297 290 283 237 253 275 277 257 270 244 242 292 291 298 309 266 262
7.0 238 232 263 255 247 256 229 221 287 284 282 288 280 273 231 245 267 270 247 261 235 232 281 283 286 299 254 249
7.5 231 226 255 250 238 247 222 213 272 277 272 279 272 264 222 236 260 260 238 249 228 224 272 272 274 289 248 242
8.0 222 219 248 244 233 239 215 205 265 267 266 272 264 258 216 230 253 253 231 241 223 217 263 264 273 281 243 235
8.5 216 212 244 237 226 231 209 201 259 259 259 266 257 252 208 223 245 246 223 233 216 209 256 257 0 274 235 229
9.0 213 211 241 236 223 224 204 195 255 256 259 259 254 245 204 219 245 245 222 231 212 208 252 256 0 273 233 226
Kenneth Lehner
> Kenneth Lehner writes:
>
> > Jobst once proclaimed that it is impossible to get a draft behind
> > another swimmer because the leading swimmer is pushing water
> > backwards, thus inhibiting the forward progress of the trailing
> > swimmer. Not only did Jobst not understand the physics of human
> > swimming, but he showed his lack of practical experience in the
> > matter.
>
> I think you confuse surface waves with currents in water. The swimmer
> moves forward in a medium getting no reaction from outside the medium
> (such as pushing off from a fixed object). The only means of
> propulsion is kinetic reaction. Since the volume of water displaced
> does not end up at the destination, but flows around the body, it has
> a rearward velocity as it passes the swimmer and the swimmer must
> accelerate water rearward to overcome viscous losses. Therefore,
> there must be a net rearward flow after the passing of a self
> propelled body.
I think you thunk wrong :-)My sincere thanks for the prompt to have some
interesting discussionswith some swimmers to try to determine what is
going on. We came up
with some ideas:
Water is dense. Swimmers don't move water for propulsion so much
as push against it. The water "pushed against" does move backwards,
but said motion is quickly damped by the water surrounding it. Any
movement of this water disappears long before a trailing swimmer
encounters it. The effect *is* like pushing against a fixed object (the
whole pool)!
The water pushed backwards by the arms is a narrow strip that is
overwhelmed by the large volume of the surrounding pool. Contrast
this water with that displaced by the beer-can shaped (as suggested
by my beer-swilling swimming partner) volume of the swimmer's body.
This mass (which is pulled forward behind the body; is this similar to the
effect of air pushing forward behind a large truck?) stays together for
quite a distance before being damped by the rest of the pool. It is this
mass of water that the trailing swimmer encounters, thus reducing the
effort needed. I could feel this in the pool two days ago, when I was
roughly seven yards behind the single swimmer in front of me.
In fact, a large body of water *does* end up at the destination (say the
other end of the pool). In a two-length-of-the-pool race (say a 50yd
freestyle in a 25yd pool), the swimmers *must* come off the far wall
well below the surface of the water to avoid the wall of water that is
*trailing* the swimmers into the far wall. If you don't, you might as
well just get out of the pool. It is that strong.
The "net rearward flow" exists only briefly, before any backward
moving water is damped by the surrounding (still) water. The larger
chunk of water pulled forward exists for many yards.
> This is the only claim I made with respect to this discussion.
Au contraire.From DejaNews:--------------------------
Subject: Re: Triathlon with drafting
From: jbr...@hpl.hp.com (Jobst Brandt)
Date: 1995/08/24
Message-ID: <DDu29...@hpl.hp.com>
Newsgroups: rec.bicycles.racing
Brad Anders writes:
> BTW, drafting in the swim segment has gone on for years, and has
> added some tactical considerations to the swim, too. Since the
> benefit of the swim draft is considerably less than the draft you
> get on the bike, the swim draft only favored athletes who were very
> similar in their unaided swim speed.
Drafting in water is generally counterproductive as it is in the air,
because propulsion is by the medium that must be used as a reaction to
forward motion. Hence, there is rearward flow after the passage of a
swimmer, boat, or aircraft.
------------------------------------------------------
"Drafting in water is generally counterproductive..." was a claim made by
Jobst
in this discussion. Anyone who has swim in lanes or open water with other
swimmers knows that drafting is very productive.
> > (Highest achieved human swim speed is 5 to 6mph, due to the amount
> > of effort required to move water out of the way (i.e., *forward*);
> > anyone who has ever drafted another swimmer can clearly feel the
> > increased speed/decreased effort of the trailing swimmer; casual
> > observation of a freestyle sprint will see a (literal) wall of water
> > follow the swimmers into the wall).
>
> How do you reconcile this with propulsion in a fluid medium.
Water (in the context of human swimming) is more like a solid thana fluid
regarding propulsion. As I said, human swimming technique
(at least the arm motion in the crawl, fly, back, and part of the
breaststroke)
tries to anchor the hand/arm in roughly one place. Doc Councilman
noted (for the first time) that Mark Spitz' hand came out of the water at
the end of his stroke *in front of* where it entered the water. Spitz was
able to not just anchor his hand in the water, but generate lift which
pulled his hand forward.
Ken Lehner
BikeTires
Thanks Jobst,
Substantial amount of information, gotta do some reading and studying now.
Mike Sullivan
Jobst Brandt
Kenneth Lehner writes:
>> I think you confuse surface waves with currents in water. The
>> swimmer moves forward in a medium getting no reaction from outside
>> the medium (such as pushing off from a fixed object). The only
>> means of propulsion is kinetic reaction. Since the volume of water
>> displaced does not end up at the destination, but flows around the
>> body, it has a rearward velocity as it passes the swimmer and the
>> swimmer must accelerate water rearward to overcome viscous losses.
>> Therefore, there must be a net rearward flow after the passing of a
>> self propelled body.
> Water is dense. Swimmers don't move water for propulsion so much
> as push against it. The water "pushed against" does move backwards,
> but said motion is quickly damped by the water surrounding it. Any
> movement of this water disappears long before a trailing swimmer
> encounters it. The effect *is* like pushing against a fixed object (the
> whole pool)!
Please review what the previous paragraph stated. Your vague "pushes
against" makes no sense. From what is the swimmer getting the reaction
to "push against"? If you are suspended in a fluid medium, the only
method of propulsion is by accelerating that medium in the opposite
direction. You are not pushing against a fixed object.
> The water pushed backwards by the arms is a narrow strip that is
> overwhelmed by the large volume of the surrounding pool. Contrast
> this water with that displaced by the beer-can shaped (as suggested
> by my beer-swilling swimming partner) volume of the swimmer's body.
I don't see what the displaced water has to do with propulsion other
than causing surface waves that hinder motion and skin drag of passing
water. The water in the pool is not being stirred by a man on the end
of a spoon.
> This mass (which is pulled forward behind the body; is this similar
> to the effect of air pushing forward behind a large truck?) stays
> together for quite a distance before being damped by the rest of the
> pool.
A large truck is being propelled by the solid road and moving through
a fluid medium that is not necessary for moving or supporting the
truck. There is no parallel between a ground based vehicle surrounded
by a gas and a swimmer propelling himself in water.
> It is this mass of water that the trailing swimmer encounters, thus
> reducing the effort needed. I could feel this in the pool two days
> ago, when I was roughly seven yards behind the single swimmer in
> front of me.
I think you imagined it. You present no explanation of why the effect
you perceived should occur. Besides, you conveniently disagree with
your earlier statement that: "Any movement of this water disappears
long before a trailing swimmer encounters it."
> In fact, a large body of water *does* end up at the destination (say
> the other end of the pool). In a two-length-of-the-pool race (say a
> 50yd freestyle in a 25yd pool), the swimmers *must* come off the far
> wall well below the surface of the water to avoid the wall of water
> that is *trailing* the swimmers into the far wall. If you don't,
> you might as well just get out of the pool. It is that strong.
First, the "wall of water" is a surface wave and is not moving water.
If your water theory were fact, as you call it, the oceans would be
empty, their waves carrying all the water toward land. No net water
moves. The reason for turning under water is that pushing off on the
surface causes surface waves that dissipate far more energy than skin
friction under water. There are rules for how far a swimmer may swim
under water for this reason.
> The "net rearward flow" exists only briefly, before any backward
> moving water is damped by the surrounding (still) water. The larger
> chunk of water pulled forward exists for many yards.
Conservation of momentum makes this statement patently false. I think
your hand waving physics is an imposition in a technical discussion.
You throw up more false targets than I prefer to chase. Chunks of
water are not moving, but if the water that is is what you call chunks,
then there must be more going rearward than forward or there would be no
forward motion. Skin friction and surface waves are generated by this
motion and the reaction force is rearward flow.
>> This is the only claim I made with respect to this discussion.
> From DejaNews:--------------------------
> Subject: Re: Triathlon with drafting
> From: jbr...@hpl.hp.com (Jobst Brandt)
> Date: 1995/08/24
> Message-ID: <DDu29...@hpl.hp.com>
> Newsgroups: rec.bicycles.racing
> Brad Anders writes:
>> BTW, drafting in the swim segment has gone on for years, and has
>> added some tactical considerations to the swim, too. Since the
>> benefit of the swim draft is considerably less than the draft you
>> get on the bike, the swim draft only favored athletes who were very
>> similar in their unaided swim speed.
> Drafting in water is generally counterproductive as it is in the air,
> because propulsion is by the medium that must be used as a reaction to
> forward motion. Hence, there is rearward flow after the passage of a
> swimmer, boat, or aircraft.
> ------------------------------------------------------
> "Drafting in water is generally counterproductive..." was a claim
> made by Jobst in this discussion. Anyone who has swim in lanes or
> open water with other swimmers knows that drafting is very
> productive.
You'll notice that there is a caveat in that statement and that is
"open water". The primary advantage lies in smooth water rather than
the drafting that is proposed. Turbulence of a passing swimmer leaves
a smother surface behind than open water that usually has a degree of
chop on it.
>>> (Highest achieved human swim speed is 5 to 6mph, due to the amount
>>> of effort required to move water out of the way (i.e., *forward*);
>>> anyone who has ever drafted another swimmer can clearly feel the
>>> increased speed/decreased effort of the trailing swimmer; casual
>>> observation of a freestyle sprint will see a (literal) wall of water
>>> follow the swimmers into the wall).
>> How do you reconcile this with propulsion in a fluid medium.
> Water (in the context of human swimming) is more like a solid than a
> fluid regarding propulsion. As I said, human swimming technique (at
> least the arm motion in the crawl, fly, back, and part of the
> breaststroke) tries to anchor the hand/arm in roughly one place.
That is pure magic. Water is a fluid and not more like a solid. In
fact water is the quintessential liquid and is a good example for most
liquids, liquids being relatively incompressible fluids in contrast to
gases. There is no way a swimmer's arm can push off of stationary
water other than accelerating it in the opposite direction. Please
address this concept if you think fluid propulsion occurs differently.
> Doc Councilman noted (for the first time) that Mark Spitz' hand came
> out of the water at the end of his stroke *in front of* where it
> entered the water. Spitz was able to not just anchor his hand in
> the water, but generate lift which pulled his hand forward.
Who is Doc and by what measure did he determine that this occurred? I
suspect that he is sports announcer like Phil Ligget who (among many
other incredible things) stated that Sean Kelly was such a strong
bicycle racer that he could burn rubber with his back wheel on clean
dry pavement, sitting in the saddle. Doc's comment seems equally
accurate and also attributed to a hero greater than life.
Ligget's comment was offered here at Stanford University when he
appeared with Eddie Merckx last year.
Jobst Brandt <jbr...@hpl.hp.com>
Robert L. Frazier
I use tubulars, but I must admit that the main reasons have nothing to do with
speed. One reason is that they *sound* nicer (for me, cycling is an aesthetic
experience); the second is that I *hate* changing flat clinchers, but don't
mind fixing the occasional flat tubular (while listening to BBC4).
Bye the bye. If I remember correctly, there is some advantage to someone
drafting on you, and some explanation of this based on the nature of the flow
of air. However, I could be entirely wrong (it could be a myth). Next time I'm
into dinner at college, I'll ask a physicist who is concerned with various
types of flow, e.g., air and fluids. Whatever response I get, I'll try to get
some reference to the research on this area. Without such a reference, the
discussion is rather arid.
Best wishes,
Bob
--
Robert L. Frazier EMAIL: robert....@christ-church.ox.ac.uk
Christ Church TELEPHONE: +44 1865 276493
Oxford OX1 1DP FAX: +44 1865 794199
UK
Eric Salathe
Kenneth Lehner, who probably has no idea who G K Batchelor is, wrote:
> Jobst once proclaimed that it is impossible to get a draft behind
> another swimmer because the leading swimmer is pushing water
> backwards, thus inhibiting the forward progress of the trailing
> swimmer. Not only did Jobst not understand the physics of human
> swimming, but he showed his lack of practical experience in the
> matter.
No time for a first course in fluid mechanics, but as I recall from
being on the swim team in college, getting in front of the `wave' was
essential to doing well in a sprint. Swimmers caught behind in the wake
struggled.
> Water (in the context of human swimming) is more like a solid than a fluid
> regarding propulsion.
Bertrand Russel claimed that, assuming any false statement, one could
prove any falsehood. He was challanged to prove that if one equals two,
he was the Pope. His response: `The pope and I are two, therefore we are
one.' So I guess this tread has proven that, if tubulars are better than
clincers, people can swim in solid ice.
--
,
Eric P. Salathe, Jr. sal...@atmos.washington.edu
Seattle WA
evans-the-swim
>Kenneth Lehner, who probably has no idea who G K Batchelor is, wrote:
>> Jobst once proclaimed that it is impossible to get a draft behind
>> another swimmer because the leading swimmer is pushing water
>> backwards, thus inhibiting the forward progress of the trailing
>> swimmer. Not only did Jobst not understand the physics of human
>> swimming, but he showed his lack of practical experience in the
>> matter.
A presumption of JB's athletic abilities that seems to be
unsubstantiated. However, there has been measured a significant
energy expenditure decrease for a following swimmer. This was done at
the US Colorado Springs centre in a flume with lots of instrumentation
- blood, gas, 3-axis video and stroke analysis, etcetera. I do not
remember the exact numbers, but they were of the order that swimming 3
metres behind was good for some small number of seconds of eqivalent
swimming time over 100 metres. This was in response to a question
asked at a conference I attended, I do not know if it has been
published.
>
>No time for a first course in fluid mechanics, but as I recall from
>being on the swim team in college, getting in front of the `wave' was
>essential to doing well in a sprint. Swimmers caught behind in the wake
>struggled.
This refers to an entirely different phenomenon - the displacement
wave. This extends at almost 90 degreees to the motion of travel,
unlike the wake. Any body ahead of this wave could (I have no
knowledge of studies on this point) gain something from this - it
depends on the height of the wave. If it works, it's probably small,
so you'd want to be in the middle lane of a sprint heat with 8 big
guys to really surf. I did the 1500 and so have no (well, little)
direct experience.
>
>> Water (in the context of human swimming) is more like a solid than a fluid
>> regarding propulsion.
Perhaps best restated as water, although fluid like a gas, is
essentially incompressible. And thus, armchair analysis of the draft
of cyclists by analogy with swimmers is a vain pursuit.
tku...@diabloresearch.com
In article <6es49r$m...@hplntx.hpl.hp.com>,
jbr...@hpl.hp.com (Jobst Brandt) wrote:
>
>
> Please review what the previous paragraph stated. Your vague "pushes
> against" makes no sense. From what is the swimmer getting the reaction
> to "push against"? If you are suspended in a fluid medium, the only
> method of propulsion is by accelerating that medium in the opposite
> direction. You are not pushing against a fixed object.
Err, Jobst, I didn't see what the original posting on this subject was
but this appears to be an argument in which you claim that swimmers
don't obtain any benefit from 'drafting' another swimmer except through
the wave-flattening effects of the front swimmer.
The propulsion of a swimmer is mostly in his hands and arms with a
smaller proportion in his feet and legs. The vast majority of the
water behind a swimmer is moving _with_ the swimmer and not in the
opposite direction. v^2 and all that jazz, you know.
Drafting has been shown to be very successful in bodies of water large
enough to qualify as your 'open water' while being small enough to not
suffer from chop that the leading swimmer would plough down for the
drafter.
The effect is very large and that is why there is so much pressure from
the good swimmers to outlaw drafting in triathlons.
Jobst Brandt
This data set includes the tubulars and Michelin tires.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Jobst Brandt <jbr...@hpl.hp.com>
------------------------------------------------------------------------
700x25C, 700x28C Tires and Vittoria and Clement Tubulars
Rolling resistance (g) vs. pressure (kg/cm2) @ 50 kg load
Col 1 - Inflation pressure (kg/cm2)
Col 2 - S Touring 25C
Col 3 - S Touring II 25C
Col 4 - S Ultra L 25C
Col 5 - S Turbo 25
Col 6 - M HiLite Comp 20C
Col 7 - Avocet 20 25C
Col 8 - Avocet 30 25C
Col 9 - Vittoria CX
Col 10 - Clement Seta 250
Col 11 - S Touring 28C
Col 12 - S Touring II 28C
Col 13 - S turbo 28C
Col 14 - M HiLite 23C
Col 15 - Avocet 20 28C
Col 16 - Avocet 30 28C
c1 c2 c3 c4 c5 c6 c7 c8 c9 c10 c11 c12 c13 c14 c15 c16
3.5 576 531 480 444 493 421 417 423 408 531 521 508 434 390 384
4.0 522 483 437 408 440 390 377 398 385 484 472 453 389 360 356
4.5 483 441 399 378 399 365 343 380 366 451 433 415 358 340 331
5.0 452 408 373 353 374 345 326 362 351 423 403 388 339 322 311
5.5 427 379 351 334 350 327 309 348 339 403 381 369 320 307 296
6.0 402 359 334 316 330 312 293 336 330 384 362 351 302 295 283
6.5 379 340 320 301 311 299 281 327 321 370 347 334 287 284 270
7.0 362 324 309 287 296 285 270 321 314 357 333 322 277 274 260
7.5 348 313 297 277 281 274 260 317 307 344 321 311 267 267 250
8.0 335 301 286 267 270 267 254 311 302 335 312 302 260 259 243
8.5 323 294 280 261 259 260 248 306 294 329 305 295 254 252 238
9.0 312 285 273 255 256 256 242 305 289 323 300 290 249 248 234
Kenneth Lehner
> Kenneth Lehner writes:
>
> >> I think you confuse surface waves with currents in water. The
> >> swimmer moves forward in a medium getting no reaction from outside
> >> the medium (such as pushing off from a fixed object). The only
> >> means of propulsion is kinetic reaction. Since the volume of water
> >> displaced does not end up at the destination, but flows around the
> >> body, it has a rearward velocity as it passes the swimmer and the
> >> swimmer must accelerate water rearward to overcome viscous losses.
> >> Therefore, there must be a net rearward flow after the passing of a
> >> self propelled body.
>
> > Water is dense. Swimmers don't move water for propulsion so much
> > as push against it. The water "pushed against" does move backwards,
> > but said motion is quickly damped by the water surrounding it. Any
> > movement of this water disappears long before a trailing swimmer
> > encounters it. The effect *is* like pushing against a fixed object (the
> > whole pool)!
>
> Please review what the previous paragraph stated. Your vague "pushes
> against" makes no sense. From what is the swimmer getting the reaction
> to "push against"? If you are suspended in a fluid medium, the only
> method of propulsion is by accelerating that medium in the opposite
> direction. You are not pushing against a fixed object.
I said "the effect is like pushing against a fixed object", not "the effectis
the same as pushing against a fixed object". I also said that the water
*does* move backwards. Pushing against water with the human hand
and arm is much more like pushing against a wall than it is like pushing
against air. When you push against a wall, *the wall moves*. But not
much (vanishingly little). There's a whole bunch of mass behind it
(eventually connected to the earth). When you push against water,
the water moves. But not a lot (in the human swimmer case). There's a
whole bunch of mass behind the water (the rest of the pool). The moved
water very quickly imparts its energy to the rest of the water, and is
dissipated. Not to be felt by the trailing swimmer.
> > The water pushed backwards by the arms is a narrow strip that is
> > overwhelmed by the large volume of the surrounding pool. Contrast
> > this water with that displaced by the beer-can shaped (as suggested
> > by my beer-swilling swimming partner) volume of the swimmer's body.
>
> I don't see what the displaced water has to do with propulsion other
> than causing surface waves that hinder motion and skin drag of passing
> water. The water in the pool is not being stirred by a man on the end
> of a spoon.
"Please review what the previous paragraph stated". I never said the
displacedwater caused by the body had anything to do with propulsion, did I?
You lost me with the spoon analogy, I'm afraid.
> > This mass (which is pulled forward behind the body; is this similar
> > to the effect of air pushing forward behind a large truck?) stays
> > together for quite a distance before being damped by the rest of the
> > pool.
>
> A large truck is being propelled by the solid road and moving through
> a fluid medium that is not necessary for moving or supporting the
> truck. There is no parallel between a ground based vehicle surrounded
> by a gas and a swimmer propelling himself in water.
You said (elsewhere) that air behind a truck actually moves forward andpresses
against the back of the truck. I never said it contributes to moving
or supporting the truck. I was observing that a similar phenomenon occurs
when a mass of water actually moves forward behind the swimmer. It has
nothing to do with propulsion (a swimmer being dragged by an airplane would
exhibit the same phenomenon). You misunderstood me; I apologize for the
lack of clarity.
> > It is this mass of water that the trailing swimmer encounters, thus
> > reducing the effort needed. I could feel this in the pool two days
> > ago, when I was roughly seven yards behind the single swimmer in
> > front of me.
>
> I think you imagined it. You present no explanation of why the effect
> you perceived should occur. Besides, you conveniently disagree with
> your earlier statement that: "Any movement of this water disappears
> long before a trailing swimmer encounters it."
You are wrong. It is real. Exactly 100% of swimmers who have draftedanother
swimmer will attest to it. No myth, no lore. As for convenience,
your quoted text refers to the water moved via propulsion due to the
arms; the water moved by the body (*not* from propulsion) is moving
*forward*, and is much less easily damped (due to the more cylindrical
shape). Two different masses of water, with very different shapes. No
disagreement.
I have presented an explanation:
1) the water moved backwards by the hands and arms is damped by the
surrounding water (due to the long, narrow shape of the affected volume)
2) the water displaced by the rest of the body fills the space left by the
body
> > In fact, a large body of water *does* end up at the destination (say
> > the other end of the pool). In a two-length-of-the-pool race (say a
> > 50yd freestyle in a 25yd pool), the swimmers *must* come off the far
> > wall well below the surface of the water to avoid the wall of water
> > that is *trailing* the swimmers into the far wall. If you don't,
> > you might as well just get out of the pool. It is that strong.
>
> First, the "wall of water" is a surface wave and is not moving water.
> If your water theory were fact, as you call it, the oceans would be
> empty, their waves carrying all the water toward land. No net water
> moves. The reason for turning under water is that pushing off on the
> surface causes surface waves that dissipate far more energy than skin
> friction under water. There are rules for how far a swimmer may swim
> under water for this reason.
How does the body create this "surface wave" that is moving forwardand is
behind the swimmer? This is not the bow wave that also plays
a part in swimming drafting strategy. Anyone standing within 5 feet
of the wall when sprinters turn will get splashed. I may not understand
what's going on, but it sure seems like water is moving.
As for turning under water, you are partially correct, but partially wrong.
Yes, it is more efficient to be underwater than on the surface. But there
is a huge wave that will stop the swimmer dead in his lane that is trailing
the swimmers. In fact, it's so far behind them that the swimmers have time
to turn and push off before it arrives.
You're dead wrong about the "rules for how far a swimmer may swim under
water for this reason". There are no rules for how far a swimmer may swim
under water for the freestyle, nor for the butterfly. There is no rule for
how
far a breaststroker may go underwater (only that he must come up prior to
finishing his second pull). The underwater rule for the backstroke arose
recently because David Berkoff's style was no longer considered "backstroke";
it's an esthetic rule.
> > The "net rearward flow" exists only briefly, before any backward
> > moving water is damped by the surrounding (still) water. The larger
> > chunk of water pulled forward exists for many yards.
>
> Conservation of momentum makes this statement patently false. I think
> your hand waving physics is an imposition in a technical discussion.
> You throw up more false targets than I prefer to chase. Chunks of
> water are not moving, but if the water that is is what you call chunks,
> then there must be more going rearward than forward or there would be no
> forward motion. Skin friction and surface waves are generated by this
> motion and the reaction force is rearward flow.
My apologies for misleading you into thinking that the momentum mysteriously
disappears. Of course, the momemtum is conserved. I say that it is
dissipated
to the point where it no longer has an effect on the trailing swimmer. The
momentum is spread out over far more water molecules (and thus volume)
than the trailing swimmer will contact.
Talk about false targets! You said you didn't make any other claims. I
postedyour claim. Now you address open water! Do you still stand by your
claim
that "drafting in water is generally counterproductive"?
> > Water (in the context of human swimming) is more like a solid than a
> > fluid regarding propulsion. As I said, human swimming technique (at
> > least the arm motion in the crawl, fly, back, and part of the
> > breaststroke) tries to anchor the hand/arm in roughly one place.
>
> That is pure magic. Water is a fluid and not more like a solid. In
> fact water is the quintessential liquid and is a good example for most
> liquids, liquids being relatively incompressible fluids in contrast to
> gases. There is no way a swimmer's arm can push off of stationary
> water other than accelerating it in the opposite direction. Please
> address this concept if you think fluid propulsion occurs differently.
A very good swimmer will take approximately 12-15 strokes per 25 yards.This is
about six feet per arm rotation. Measure the distance from the tip
of your finger when your arm is raised above your head, to the tip of your
finger when your arm is by your side. Add a little for a glide at the top of
the stroke. Just about six feet. A very good swimmer's hand moves
backwards *very little*. Go to a Stanford swim meet or practice and explain
how this happens.
> > Doc Councilman noted (for the first time) that Mark Spitz' hand came
> > out of the water at the end of his stroke *in front of* where it
> > entered the water. Spitz was able to not just anchor his hand in
> > the water, but generate lift which pulled his hand forward.
>
> Who is Doc and by what measure did he determine that this occurred? I
> suspect that he is sports announcer like Phil Ligget who (among many
> other incredible things) stated that Sean Kelly was such a strong
> bicycle racer that he could burn rubber with his back wheel on clean
> dry pavement, sitting in the saddle. Doc's comment seems equally
> accurate and also attributed to a hero greater than life.
Sorry, I assumed you'd know who he was.Doc Councilman did quantitative
measurement and analysis while at IndianaUniversity where Spitz swam. He was
trying to understand why the best
swimmers arms followed an S-shaped pattern, rather than the straight line
they were being taught. It's the difference between a propeller and a
paddle-wheel, which seems to be how you think good swimmers swim.
> Ligget's comment was offered here at Stanford University when he
> appeared with Eddie Merckx last year.
And this is relevant how?
I have a tremendous amount of respect for Mr. Brandt's bicycling knowledge,
but he is all wet when it comes to swimming.
Ken Lehner
Jobst Brandt
Tom Kunich writes:
> The propulsion of a swimmer is mostly in his hands and arms with a
> smaller proportion in his feet and legs. The vast majority of the
> water behind a swimmer is moving _with_ the swimmer and not in the
> opposite direction. v^2 and all that jazz, you know.
You have described a perpetual motion machine. Not only does your
swimmer move himself forward in water, but also the water. What is
the means of propulsion?
> Drafting has been shown to be very successful in bodies of water
> large enough to qualify as your 'open water' while being small
> enough to not suffer from chop that the leading swimmer would plough
> down for the drafter.
Yes, and what is the effect that makes this possible. Rather than
repeating this mantra, you might explain what the effect is. However,
I don't see that we will get anywhere in this discussion if you
believe that the passing of a swimmer moves both the swimmer and the
water through which he swims in the same direction. This is not
possible.
Of course this is all in the pursuit of the tubular tire discussion.
Don;t lose sight of the original question from which this is a dodge
introduced by those who make open ended wishful claims for their
preferred type of equipment. The dodge is working.
Jobst Brandt <jbr...@hpl.hp.com>
Ken Ferschweiler
Jobst Brandt (jbr...@hpl.hp.com) wrote:
: Kenneth Lehner writes:
: > Doc Councilman noted (for the first time) that Mark Spitz' hand came
: > out of the water at the end of his stroke *in front of* where it
: > entered the water. Spitz was able to not just anchor his hand in
: > the water, but generate lift which pulled his hand forward.
: Who is Doc and by what measure did he determine that this occurred?
Actually, this is pretty well known among swimmers, and pretty simple.
A skilled swimmer moves his hand sideways through the water and it acts
as a foil, generating lift. The hand really does move forward - which,
of course, in no way conflicts with the analysis that the water moves
backwards.
Frank Krygowski
Is this an analogous situation? I'm not sure, but I thought I'd throw it
out for consideration:
In certain ways, a swimmer may be like a plane with a jet engine. The
plane gets its forward motion by ejecting mass to its rear. Conservation
of momentum means the high speed, low mass rearward jet of gas produces a
(lower) forward speed in the high mass of the plane itself.
Is this similar to what a swimmer does? Seems to me it's likely. There
would be a stream of higher speed water pushed back by the swimmers
hands and feet.
As to the presence or absence of a "draft" in the direction of motion:
If a jet plane were to fly by you at a distance of 10 feet, do you imagine
you'd feel a wind blast _opposite_ the direction of the plane's travel,
or _in_ the direction of the plane's travel? Or none at all?
I imagine it would be in the direction of the plane's travel.
So: how similar are the two situations?
--
Frank Krygowski ae...@yfn.ysu.edu
James Neale
Jobst Brandt wrote in message <6eouuh$k...@hplntx.hpl.hp.com>...
>
>I find $12 to $15 plus shipping and lost time an unreasonable
>alternative to sticking a patch on a tube.
Purely a subjective response as to which others can and do
differ.
I am not sure what "lost time" means in the above context.
Changing a tubular (using a CO2 cartridge for inflation)
takes about 2 minutes. You're back on the bike before
you even cool down.
J. Neale
Jobst Brandt
Kenneth Lehner writes:
>>>> I think you confuse surface waves with currents in water. The
>>>> swimmer moves forward in a medium getting no reaction from
>>>> outside the medium (such as pushing off from a fixed object).
>>>> The only means of propulsion is kinetic reaction. Since the
>>>> volume of water displaced does not end up at the destination, but
>>>> flows around the body, it has a rearward velocity as it passes
>>>> the swimmer and the swimmer must accelerate water rearward to
>>>> overcome viscous losses. Therefore, there must be a net rearward
>>>> flow after the passing of a self propelled body.
>>> Water is dense. Swimmers don't move water for propulsion so much
>>> as push against it. The water "pushed against" does move
>>> backwards, but said motion is quickly damped by the water
>>> surrounding it. Any movement of this water disappears long before
>>> a trailing swimmer encounters it. The effect *is* like pushing
>>> against a fixed object (the whole pool)!
>> Please review what the previous paragraph stated. Your vague
>> "pushes against" makes no sense. From what is the swimmer getting
>> the reaction to "push against"? If you are suspended in a fluid
>> medium, the only method of propulsion is by accelerating that
>> medium in the opposite direction. You are not pushing against a
>> fixed object.
> I said "the effect is like pushing against a fixed object", not "the
> effect is the same as pushing against a fixed object". I also said
> that the water *does* move backwards. Pushing against water with the
> human hand and arm is much more like pushing against a wall than it
> is like pushing against air. When you push against a wall, *the
> wall moves*. But not much (vanishingly little). There's a whole
> bunch of mass behind it (eventually connected to the earth). When
> you push against water, the water moves. But not a lot (in the
> human swimmer case). There's a whole bunch of mass behind the water
> (the rest of the pool). The moved water very quickly imparts its
> energy to the rest of the water, and is dissipated. Not to be felt
> by the trailing swimmer.
Your analogy does not apply because a wall is a solid. Solids have
shape and unless deformed with sufficient force their shape is
maintained. That is why one can push off from a solid anchored abject
regardless of whether it flexes elastically or not. You cannot push
off from a liquid, because it has neither shape nor memory, it flows
out of the way of a force. The only way to propel an object suspended
in a fluid medium is by kinetic reaction. That means by propelling
the fluid in the opposite direction, as in jet propulsion.
>>> It is this mass of water that the trailing swimmer encounters, thus
>>> reducing the effort needed. I could feel this in the pool two days
>>> ago, when I was roughly seven yards behind the single swimmer in
>>> front of me.
>> I think you imagined it. You present no explanation of why the effect
>> you perceived should occur. Besides, you conveniently disagree with
>> your earlier statement that: "Any movement of this water disappears
>> long before a trailing swimmer encounters it."
> You are wrong. It is real. Exactly 100% of swimmers who have
> drafted another swimmer will attest to it.
Assuming this is correct, it must arise from the rearward water being
directed either to the sides or downward. However, since part of the
propulsion comes from the feet, this part is in the middle of the
swimmers path and is not dispersed.
> No myth, no lore. As for convenience, your quoted text refers to
> the water moved via propulsion due to the arms; the water moved by
> the body (*not* from propulsion) is moving *forward*, and is much
> less easily damped (due to the more cylindrical shape). Two
> different masses of water, with very different shapes. No
> disagreement.
The net movement of the water must be in the opposite direction of
progress for the swimmer. There must be conservation of momentum.
> I have presented an explanation:
> 1) the water moved backwards by the hands and arms is damped by the
> surrounding water (due to the long, narrow shape of the affected
> volume)
> 2) the water displaced by the rest of the body fills the space left
> by the body
The net movement of the water must be in the opposite direction of
progress for the swimmer. There must be conservation of momentum.
>>> In fact, a large body of water *does* end up at the destination (say
>>> the other end of the pool). In a two-length-of-the-pool race (say a
>>> 50yd freestyle in a 25yd pool), the swimmers *must* come off the far
>>> wall well below the surface of the water to avoid the wall of water
>>> that is *trailing* the swimmers into the far wall. If you don't,
>>> you might as well just get out of the pool. It is that strong.
>> First, the "wall of water" is a surface wave and is not moving water.
>> If your water theory were fact, as you call it, the oceans would be
>> empty, their waves carrying all the water toward land. No net water
>> moves. The reason for turning under water is that pushing off on the
>> surface causes surface waves that dissipate far more energy than skin
>> friction under water. There are rules for how far a swimmer may swim
>> under water for this reason.
> How does the body create this "surface wave" that is moving
> forward and is behind the swimmer? This is not the bow wave that
> also plays a part in swimming drafting strategy. Anyone standing
> within 5 feet of the wall when sprinters turn will get splashed. I
> may not understand what's going on, but it sure seems like water is
> moving.
I think if you look at any fluid mechanics text, you'll find a diagram
of a canoe shaped boat (pointed ends) generating a wave. The front
one occurs from the lateral displacement of water as the body
approaches and the rear one occurs from the closure of that
separation. This wave motion is what gives the hull speed limitation
of surface vessels. The longer the vessel the faster it can go
before it is climbing too steep a wave that it creates by its motion.
> As for turning under water, you are partially correct, but partially wrong.
> Yes, it is more efficient to be underwater than on the surface. But there
> is a huge wave that will stop the swimmer dead in his lane that is trailing
> the swimmers. In fact, it's so far behind them that the swimmers have time
> to turn and push off before it arrives.
> You're dead wrong about the "rules for how far a swimmer may swim
> under water for this reason". There are no rules for how far a
> swimmer may swim under water for the freestyle, nor for the
> butterfly. There is no rule for how far a breaststroker may go
> underwater (only that he must come up prior to finishing his second
> pull). The underwater rule for the backstroke arose recently
> because David Berkoff's style was no longer considered "backstroke";
> it's an esthetic rule.
That sounds like a rule that he can't stay underwater to me. The
definition of the second pull means only that he may complete his turn
and resume swimming but must surface. You may see it as aesthetic but
it is a limitation for the reason that surface swimming is the event
and to avoid that perverts the competition into who can stay under
longer.
>>> The "net rearward flow" exists only briefly, before any backward
>>> moving water is damped by the surrounding (still) water. The larger
>>> chunk of water pulled forward exists for many yards.
>> Conservation of momentum makes this statement patently false. I think
>> your hand waving physics is an imposition in a technical discussion.
>> You throw up more false targets than I prefer to chase. Chunks of
>> water are not moving, but if the water that is is what you call chunks,
>> then there must be more going rearward than forward or there would be no
>> forward motion. Skin friction and surface waves are generated by this
>> motion and the reaction force is rearward flow.
> My apologies for misleading you into thinking that the momentum
> mysteriously disappears. Of course, the momentum is conserved. I
> say that it is dissipated to the point where it no longer has an
> effect on the trailing swimmer. The momentum is spread out over far
> more water molecules (and thus volume) than the trailing swimmer
> will contact.
I think this would become clearer if the distance between swimmers
were known and the length of the trough that the swimmer generates.
If the following swimmer is close enough to swim into the leader's
trough, then he will be swimming downhill, albeit against slight
counterflow. This is a condition that is more evident off the stern
of a ship or even the rear of a boat that is not planing.
> Talk about false targets! You said you didn't make any other
> claims. I posted your claim. Now you address open water! Do you
> still stand by your claim that "drafting in water is generally
> counterproductive"?
No. The previous discussion was as this one, a derivative of a
different subject and the context was the same as you proposed, that
there is forward fluid flow behind a vessel that is propelled in that
medium. The origin of this thread was that birds, just like
bicyclists, draft from one another. In that context, the statement I
made was correct. However, there are effects that benefit following
swimmers such as smoothing the chop of open water and, if close
enough, the swimmer's trough. Neither of these are drafting in the
way that bicyclists do when propelling themselves from solid ground
against an airflow.
>>> Water (in the context of human swimming) is more like a solid than a
>>> fluid regarding propulsion. As I said, human swimming technique (at
>>> least the arm motion in the crawl, fly, back, and part of the
>>> breaststroke) tries to anchor the hand/arm in roughly one place.
>> That is pure magic. Water is a fluid and not more like a solid. In
>> fact water is the quintessential liquid and is a good example for most
>> liquids, liquids being relatively incompressible fluids in contrast to
>> gases. There is no way a swimmer's arm can push off of stationary
>> water other than accelerating it in the opposite direction. Please
>> address this concept if you think fluid propulsion occurs differently.
> A very good swimmer will take approximately 12-15 strokes per 25
> yards.This is about six feet per arm rotation. Measure the distance
> from the tip of your finger when your arm is raised above your head,
> to the tip of your finger when your arm is by your side. Add a
> little for a glide at the top of the stroke. Just about six feet.
> A very good swimmer's hand moves backwards *very little*. Go to a
> Stanford swim meet or practice and explain how this happens.
I can swim without using the arms. During practice, swimmers often
use a kick board as well as using only the arms.
>>> Doc Councilman noted (for the first time) that Mark Spitz' hand came
>>> out of the water at the end of his stroke *in front of* where it
>>> entered the water. Spitz was able to not just anchor his hand in
>>> the water, but generate lift which pulled his hand forward.
>> Who is Doc and by what measure did he determine that this occurred? I
>> suspect that he is sports announcer like Phil Ligget who (among many
>> other incredible things) stated that Sean Kelly was such a strong
>> bicycle racer that he could burn rubber with his back wheel on clean
>> dry pavement, sitting in the saddle. Doc's comment seems equally
>> accurate and also attributed to a hero greater than life.
> Sorry, I assumed you'd know who he was. Doc Councilman did
> quantitative measurement and analysis while at Indiana University
> where Spitz swam. He was trying to understand why the best swimmers
> arms followed an S-shaped pattern, rather than the straight line
> they were being taught. It's the difference between a propeller and
> a paddle-wheel, which seems to be how you think good swimmers swim.
I think you must have misinterpreted what was reported. I think it
must have been something like "his hands came out of the water ahead
of where one would expect them to", rather than ahead of where they
entered the water. I didn't see the report or hear of it so I can't
review what it stated.
>> Ligget's comment was offered here at Stanford University when he
>> appeared with Eddie Merckx last year.
> And this is relevant how?
It is similar to hands of a swimmer or oars of a rower coming out of
the water ahead of the entry point. I believe this is wishful
thinking of the same kind.
> I have a tremendous amount of respect for Mr. Brandt's bicycling
> knowledge, but he is all wet when it comes to swimming.
Most swimmers are, unless they swim in super-fluids.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
James Neale writes:
>> I find $12 to $15 plus shipping and lost time an unreasonable
>> alternative to sticking a patch on a tube.
> Purely a subjective response as to which others can and do differ.
> I am not sure what "lost time" means in the above context. Changing
> a tubular (using a CO2 cartridge for inflation) takes about 2
> minutes. You're back on the bike before you even cool down.
I'm talking about the cost and time it takes to package the tire, send
it out for repair and get it back again. This compared to putting a
patch on a tire, is what most riders consider excessive. After the
second flat, something that occurs immediately if you happen to ride
through some thorns, the disadvantage becomes more apparent.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Frank Krygowski writes:
> As to the presence or absence of a "draft" in the direction of motion:
> If a jet plane were to fly by you at a distance of 10 feet, do you imagine
> you'd feel a wind blast _opposite_ the direction of the plane's travel,
> or _in_ the direction of the plane's travel? Or none at all?
If you were behind or below but close to the path of the airplane, you
would feel a strong rearward wind. If you were above its path you
would feel a downdraft because the airplane achieves lift from the
downward momentum of air. In fact this downward flow causes eddies
that rise to both sides so that there is a counter rotating vortex
left behind. It is this vortex that will destroy a light airplane
inadvertently flown through such air. A 747 leaves a strong enough
back and downdraft behind, to prevent other aircraft from taking off
or landing for a dissipation period. Crashes have occurred from
insufficient interval.
Jobst Brandt <jbr...@hpl.hp.com>
Eric Salathe
Jobst Brandt wrote:
> This data set includes tubulars and Michelin tires.
[as well as Avocet.]
Am I correct in reading that the kevlar-beaded Avocet 30s get
considerably better rr than the wire-beaded 20s at high pressure? Why is
this the case?
--
Eric Salathe sal...@atmos.washington.edu
Seattle WA
Eric Salathe
Jobst Brandt wrote:
> So how did you like the tubular offset due to glue?
With a leaky tubular, at least you won't go slower as its pressure
drops.
--
Matt O'Toole
Eric Salathe wrote in message <35131E...@u.washington.edu>...
>Jobst Brandt wrote:
>> So how did you like the tubular offset due to glue?
>With a leaky tubular, at least you won't go slower as its pressure
>drops.
And, having tubulars in such a situation might be the difference in winning
or losing an important stage, or heck, the entire TdF. In the words of a
famous comedienne, "It could happen!"
Matt O.
Jobst Brandt
Eric Salathe writes:
>> This data set includes tubulars and Michelin tires. [as well as
>> Avocet.]
> Am I correct in reading that the Kevlar-beaded Avocet 30s get
> considerably better RR than the wire-beaded 20s at high pressure?
> Why is this the case?
I don't know, I haven't looked at the data in many years. These are
values that give an idea of what sort of differences various tires
have and may not represent performance of current tires. I also have
data on tubes that show what difference they make and this could make
the difference although conditions were supposed to be kept constant.
If anything, a Kevlar bead should give worse performance because the
bead might move against the rim more than a steel bead. That would be
the case if the casings were otherwise the same.
So how did you like the tubular offset due to glue?
Jobst Brandt <jbr...@hpl.hp.com>
Norman Yarvin
jbr...@hpl.hp.com (Jobst Brandt) wrote:
>The net movement of the water must be in the opposite direction of
>progress for the swimmer. There must be conservation of momentum.
Conservation of momentum states here that the net movement of the water
that the swimmer leaves behind must be zero. Most of the time the
swimmer is traveling at a constant speed, so his change of momentum is
zero. He doesn't need to impart any net momentum to the water.
Whether drafting is possible in any given case depends on which part of
the accelerated water the following swimmer encounters -- whether he hits
the water which is pushed backwards by the strokes, or whether he hits
the water which is pulled forwards by drag.
--
Norman Yarvin yar...@cs.yale.edu
Matt Castelein
Jobst Brandt wrote:
>
> Tom Kunich writes:
>
> > The propulsion of a swimmer is mostly in his hands and arms with a
> > smaller proportion in his feet and legs. The vast majority of the
> > water behind a swimmer is moving _with_ the swimmer and not in the
> > opposite direction. v^2 and all that jazz, you know.
>
> You have described a perpetual motion machine. Not only does your
> swimmer move himself forward in water, but also the water. What is
> the means of propulsion?
>
> > Drafting has been shown to be very successful in bodies of water
> > large enough to qualify as your 'open water' while being small
> > enough to not suffer from chop that the leading swimmer would plough
> > down for the drafter.
>
> Yes, and what is the effect that makes this possible. Rather than
> repeating this mantra, you might explain what the effect is. However,
> I don't see that we will get anywhere in this discussion if you
> believe that the passing of a swimmer moves both the swimmer and the
> water through which he swims in the same direction. This is not
> possible.
I believe I've heard this particular argument argued blue over in
rec.sport.swimming.. check dejanews if you like...
--
Purgamentum init, exit purgamentum.
- Matt Castelein - System Operator -
-=Cold Fusion Online, Rochester NY=-
Web- http://www2.rpa.net/~night1/sysop.html
Eleanor MacMaster
Not being an engineer or physicist, I have no technical knowledge
to bring to this discussion. However, I have noticed in the
course of teaching aquafit that it is easier for participants
who are following others when jogging, walking or doing other
forward moving exercises through the water. What is more
difficult -- and I consciously use this difficulty in designing
movements -- is to ask them to turn around and again move forward
through the turbulence their previous forward movement created.
I had never thought about 'drafting' in terms of water, but have
found the discusssion of this interesting. And when I think
about it, I am sure in terms of my personal experience as a
swimmer, that I do find it somewhat easier to swim when I am
following another swimmer - IF he or she is a reasonably good
swimmer. I can recall being behind swimmers that made my progress
more difficult - they were not smooth and created too much
disturbance in the water.
--
"Biker Chick"
Kenneth Lehner
> Assuming this is correct, it must arise from the rearward water being
> directed either to the sides or downward. However, since part of the
> propulsion comes from the feet, this part is in the middle of the
> swimmers path and is not dispersed.
The term for the effect that allows effective drafting is "eddy resistance"
(no relation to that other Eddy guy). This is water that comes in behind
the swimmer to replace the water displaced by the body. It is indeed
sucked along in the direction of the swimmer. See b) just below:
(From Swimming Science Journal, an article originally published as
Rushall, B. S., Holt, L. E., Sprigings, E. J., & Cappaert, J. M. (1994). A
re-evaluation of the forces in swimming. Journal of Swimming Research, 10, 6-30)
Three forms of resistance:
a.skin friction which is analogous to the "stickiness" of the swimmer for
moving through the water;
b.eddy resistance, the amount of water that is sucked along behind a swimmer
as forward progression is achieved and is proportional to the cross-sectional
area that is pushed against the water, and
c.wave-making resistance which is caused by swimmers' movements that move
large amounts of water (e.g., excessive diving of the shoulders and body at
the
butterfly entry).
Look it up. I apologize for not knowing the scientific term for this phenomenon.
> > You're dead wrong about the "rules for how far a swimmer may swim
> > under water for this reason". There are no rules for how far a
> > swimmer may swim under water for the freestyle, nor for the
> > butterfly. There is no rule for how far a breaststroker may go
> > underwater (only that he must come up prior to finishing his second
> > pull). The underwater rule for the backstroke arose recently
> > because David Berkoff's style was no longer considered "backstroke";
> > it's an esthetic rule.
>
> That sounds like a rule that he can't stay underwater to me. The
> definition of the second pull means only that he may complete his turn
> and resume swimming but must surface. You may see it as aesthetic but
> it is a limitation for the reason that surface swimming is the event
> and to avoid that perverts the competition into who can stay under
> longer.
You're trying to weasel out of it. You said "The reason for turning underwater
is that pushing off on the surface causes surface waves that dissipate
far more energy than skin friction under water. There are rules for how far a
swimmer may swim under water for this reason." The dissipation of energy
has *nothing* to do with the *one* rule (not "rules") related to *how far*
a swimmer can go under water. It is because the swimmer is no longer
doing "backstroke". They added the distance rule to redefine what was
considered "backstroke". I would expect a similar rule change to happen
to the butterfly, if enough swimmers go far enough under water. (Just
happened to the fly and the freestyle!).
> However, there are effects that benefit following
> swimmers such as smoothing the chop of open water and, if close
> enough, the swimmer's trough. Neither of these are drafting in the
> way that bicyclists do when propelling themselves from solid ground
> against an airflow.
Never said drafting in swimming is like that in cycling or by birds, forthat
matter. It ain't due to "smoothing the chop" or the "swimmer's
trough". It's eddy resistance.
Ken Lehner
Damon Rinard
[re: fourth rider must put out more power than third rider in team
pursuiting...]
Brad Anders wrote ...
>I think there may be another explanation for this increase in power.
[...]
>When a rider in a pursuit drops back to position four, they do so by
>taking a longer path AND by slowing down. To keep with the group they
>must accelerate.
I don't ride the team pursuit the way you describe. I use the banking to
take a longer path, and going up it does slow me down. But dropping down the
banking speeds me up, too. I do not usually have to accelerate to get back
on.
Damon Rinard
Damon Rinard's Bicycle Tech site:
http://home.earthlink.net/~rinard/
Rick Denney
On 20 Mar 1998 17:27:57 GMT, jbr...@hpl.hp.com (Jobst Brandt) wrote:
>You have described a perpetual motion machine. Not only does your
>swimmer move himself forward in water, but also the water. What is
>the means of propulsion?
>
>What is the effect that makes this possible. Rather than
>repeating this mantra, you might explain what the effect is. However,
>I don't see that we will get anywhere in this discussion if you
>believe that the passing of a swimmer moves both the swimmer and the
>water through which he swims in the same direction. This is not
>possible.
Here's my shot as describing how you can have a draft effect in
swimming without breaking the laws of physics:
Good swimmers get very little propulsion from kicking. In fact, the
only purpose of kicking is to provide the torque needed to rotate the
body from side to side throughout the stroke.
Most propulsion comes from the hands and arms. When the hand enters
the water, the swimmer grabs the water, which is called the catch, and
rotates the arm around the elbow until the hand is below the body and
the forearm normal to the direction of travel. Then the swimmer uses
the latissimus dorsi muscles to pull the arm downward (that is--toward
the feet). This is called the pull. At all times during the pull, the
hand and the forearm are substantially below the body. This is
important, because the hands and arms must find still water against
which to work. That means they must be below the turbulence caused by
the body's passage through the water.
The swimmer sets up a foward-moving circulation, with water at the
surface being pushed aside, only to eddy back in behind the swimmer
and ultimately creating a bit of forward flow. There is also a
circulation in the vertical plane, where the passing body pulls the
adjacent water forward while the hands and arm push deeper water
backwards. This deeper water also eddies vertically into the eddy pool
created by the swimmers body.
A following swimmer can perhaps take advantage of the forward flow in
the eddy pool.
If a swimmer has a good kick, then the drafting effect is reduced,
because some of the eddying water is pushed back. But kicking consumes
oxygen and accomplishes little, because it only pushes a bit of
laminar water into the eddy pool, if you will, but still does not make
the water go as fast as the propulsion from the arms. The benefit of
partially filling the eddy pool is not as great as the cost of
recruiting those big muscles.
>
>Of course this is all in the pursuit of the tubular tire discussion.
>Don;t lose sight of the original question from which this is a dodge
>introduced by those who make open ended wishful claims for their
>preferred type of equipment. The dodge is working.
>
I agree, and I hope I'm not contributing to the dodge. Too many good
swimmers experience drafting, and some explanation must be given, even
if it is the placebo effect. This is my attempt, and it may be wrong,
because it is only based on my feeling of the water as I swim and my
understanding of stroke mechanics. But I'm a poor swimmer and have
never been able to feel a draft in a triathlon. But all the swimmers
at my speed kick like the dickens, and I'm too timid to get that close
to those flailing feet.
Rick Denney
Take what you want and leave the rest.
Mark Drela
Lets not get downwash involved into this!
If we focus on just the motions in the direction of travel,
we can say the following:
1) Any self-propelled body without external contact deposits exactly
zero net axial momentum in the fluid behind it. The rearward momentum
added by propulsive effort exactly cancels the forward momentum added
by drag. If there is an imbalance, then the body accelerates.
This is true for a swimmer, and also for any airplane in level flight.
But it is NOT true for a cyclist or a car, since here the propulsive
momentum is deposited in the earth rather than in the fluid.
Only the drag acts on the fluid, and produces a net momentum
forward, in the direction of travel.
2) Even though there is no net momentum behind the swimmer, there
IS fore and aft motion at different locations. Just behind the
swimmer's feet there is friction-caused forward motion which can
be used for drafting. The balancing rearward motion is farther out
to the sides and below, where the arms do most of the propelling.
So a bad place to draft a swimmer is just a little off to the side.
In the wake of a car or cyclist, there is little or no aft motion
anywhere, so there's no penalty for being in a bad spot. There is
still a "best" spot where the forward motion is greatest.
Mark Drela
_______________________________
o/LO .'
O .' Gravity-Powered Technologies Lab
.' MIT Aero-Astro Department 37-475
'
Tim McNamara
In article <19980316231...@ladder03.news.aol.com>,
bike...@aol.com (BikeTires) wrote:
>opinion. As with anything in any industry a person can make a graph,
>schematic, report, etc. state just about anything you want it to state.
Actually, that's far from true. Scientific findings are just that-
findings based on the observation of the behavior of phenomena.
Interpretations (which is really what you are talking about) are sometimes
inaccurate, but those are eventually corrected by subsequent research.
Bicycling has 150 years of research and an equal amount of mythopoesis.
Facts, in general, are more reliable than myths.
In my experience in behavioral science, people who claim that the
statistics lie are usually the people whose views have just been somehow
contradicted by the results of the research. Most people would rather
change the facts than change their beliefs. Humans are often more
attached to being considered "right" than in knowing the truth. This
seems to be particularly true in bicycling.
Bicycling, like everything else in the universe, follows the laws of
physics. Many of the "facts" that Jobst contradicts here in the newsgroup
are actually nothing more than opinions that are contradicted by those
laws. If you read his explanations carefully (even without a background
in science and advanced math), Jobst's statements are grounded in
objectively observable phenomena. And, with more than 30 years of
bicycling and engineering experience, Jobst has observed a lot of
phenomena.
His posting personality is brusque, at best, and downright mean at worst.
Separate his style from the content of what he says and you may find
yourself actually learning quite a bit about what makes cycling work (and
how to make it work better for you).
--
Don't cry now, don't you cry, dry your eyes
on the wind.
-Robert Hunter
Jobst Brandt
Kenneth Lehner writes:
> The term for the effect that allows effective drafting is "eddy
> resistance" (no relation to that other Eddy guy). This is water
> that comes in behind the swimmer to replace the water displaced by
> the body. It is indeed sucked along in the direction of the
> swimmer. See b) just below:
> (From Swimming Science Journal, an article originally published as
> Rushall, B. S., Holt, L. E., Sprigings, E. J., & Cappaert, J. M.
> (1994). A re-evaluation of the forces in swimming. Journal of
> Swimming Research, 10, 6-30)
> Three forms of resistance:
> a.skin friction which is analogous to the "stickiness" of the
> swimmer for moving through the water;
> b.eddy resistance, the amount of water that is sucked along behind a
> swimmer as forward progression is achieved and is proportional to
> the cross-sectional area that is pushed against the water, and
> c.wave-making resistance which is caused by swimmers' movements that
> move large amounts of water (e.g., excessive diving of the shoulders
> and body at the butterfly entry).
> Look it up. I apologize for not knowing the scientific term for
> this phenomenon.
I find this unusual that a new concept and inappropriate terms are used
in this respect. "Eddy resistance" hasn't appeared in any fluid mechanics
test that I have encountered and "stickiness" seems to be a condescending
way for talking about fluid friction and boundary layers. Sucking is
also a term not found in scientific journals, there being no "suck" in
scientific work other than inappropriate approaches to the professor.
Fluid mechanics operates with pressures that are higher and lower, but
no suck.
>>> You're dead wrong about the "rules for how far a swimmer may swim
>>> under water for this reason". There are no rules for how far a
>>> swimmer may swim under water for the freestyle, nor for the
>>> butterfly. There is no rule for how far a breaststroker may go
>>> underwater (only that he must come up prior to finishing his
>>> second pull). The underwater rule for the backstroke arose
>>> recently because David Berkoff's style was no longer considered
>>> "backstroke"; it's an esthetic rule.
>> That sounds like a rule that he can't stay underwater to me. The
>> definition of the second pull means only that he may complete his
>> turn and resume swimming but must surface. You may see it as
>> aesthetic but it is a limitation for the reason that surface
>> swimming is the event and to avoid that perverts the competition
>> into who can stay under longer.
> You're trying to weasel out of it. You said "The reason for turning
> underwater is that pushing off on the surface causes surface waves
> that dissipate far more energy than skin friction under water.
> There are rules for how far a swimmer may swim under water for this
> reason." The dissipation of energy has *nothing* to do with the
> *one* rule (not "rules") related to *how far* a swimmer can go under
> water. It is because the swimmer is no longer doing "backstroke".
> They added the distance rule to redefine what was considered
> "backstroke". I would expect a similar rule change to happen to the
> butterfly, if enough swimmers go far enough under water. (Just
> happened to the fly and the freestyle!).
Just the same subsurface propulsion is more efficient than surface
movement as is evident in submarine and surface vessels (that do not
plane). Submarines can move distinctly faster than surface ships
because they create no surface waves, the largest dissipation of
energy for ships. A surfboarder could surf continually on the bow
wave of a ship just as albatrosses glide, wings rigid, for days on the
updrafts on bow waves of large ships. Much energy is lost in surface
waves and these are created by rearward momentum form fluid
propulsion. It is the trough between bow and stern wave that limits
the speed of a surface ship, waves having a fixed speed for a given
height in the medium in which they move.
>> However, there are effects that benefit following swimmers such as
>> smoothing the chop of open water and, if close enough, the
>> swimmer's trough. Neither of these are drafting in the way that
>> bicyclists do when propelling themselves from solid ground against
>> an airflow.
> Never said drafting in swimming is like that in cycling or by birds,
> for that matter. It ain't due to "smoothing the chop" or the
> "swimmer's trough". It's eddy resistance.
You may not have said that but your are arguing the points that those
who introduced the parallels to bicycling on this forum. OK, so now
we have a new undefined term that cures all. EDDY RESISTANCE.
Jobst Brandt <jbr...@hpl.hp.com>
Eric Salathe
Matt O'Toole wrote:
>
> Eric Salathe wrote in message <35131E...@u.washington.edu>...
> >Jobst Brandt wrote:
>
>
> >drops.
>
> And, having tubulars in such a situation might be the difference in winning
> or losing an important stage, or heck, the entire TdF. In the words of a
> famous comedienne, "It could happen!"
That was meant to be a bit sarcastic since the data show that, even at
low pressures (down to 50psi), tubulars still do worse than good
clinchers.
--
,
BikeTires
Fatigued,
I say again, I have never publicly posted a response stating Jobst was right
or wrong in his opinions or posts. I have my personal opinions about him, you,
cycling etc. I choose not to post them here.
>>opinion. As with anything in any industry a person can make a graph,
>>schematic, report, etc. state just about anything you want it to state.
>
>Actually, that's far from true. Scientific findings are just that-
>findings based on the observation of the behavior of phenomena.
>Interpretations (which is really what you are talking about) are sometimes
Could you please pull some of (which is really what you are talking about)
out of your archives, while you search please refer to my first statement at
the top of this post. I agree on interpretations, however I was refering to
the "published" test results one can find. These are on the edge of science,
but science normally involves some type of independant control during the
testing. The recent tests as advertised by Specialized were done by the JTI,
which is directly connected to Mitsuboshi. IRC test referred by Jobst were
done by IRC, the Conti test of 4 years ago were performed by Conti.
>inaccurate, but those are eventually corrected by subsequent research.
>Bicycling has 150 years of research and an equal amount of mythopoesis.
>Facts, in general, are more reliable than myths.
I'm sorry have I questioned a "true fact"?
>
>In my experience in behavioral science, people who claim that the
>statistics lie are usually the people whose views have just been somehow
>contradicted by the results of the research. Most people would rather
>change the facts than change their beliefs. Humans are often more
>attached to being considered "right" than in knowing the truth. This
>seems to be particularly true in bicycling.
>
>Bicycling, like everything else in the universe, follows the laws of
>physics. Many of the "facts" that Jobst contradicts here in the newsgroup
>are actually nothing more than opinions that are contradicted by those
>laws. If you read his explanations carefully (even without a background
>in science and advanced math), Jobst's statements are grounded in
>objectively observable phenomena. And, with more than 30 years of
>bicycling and engineering experience, Jobst has observed a lot of
>phenomena.
>
>His posting personality is brusque, at best, and downright mean at worst.
>Separate his style from the content of what he says and you may find
>yourself actually learning quite a bit about what makes cycling work (and
>how to make it work better for you).
I am pretty sure I made that apparent in a number of my posts also.
I certainly appreciate your post and your views regarding your fields of
expertise. I also appreciate your defense of Jobst as I am sure he does also.
>
>--
>Don't cry now, don't you cry, dry your eyes
>on the wind.
>
>-Robert Hunter
>
>
>
Best regards, and
Ride On.
Mike Sullivan
Vittoria North America
Don Winston
Jobst Brandt wrote:
>
>So how did you like the tubular offset due to glue?
>
I plotted the data in Excel, and it makes a strong case for not riding
tubulars. Jobst, do you have the data for hard and soft glue? Or at
least the value of the offset?
Don Winston <dwin...@erols.com>
John Olsen
In article <6f1na4$r...@senator-bedfellow.MIT.EDU>, dr...@mit.edu (Mark Drela) says:
>
>In article <6euqaf$h...@hplntx.hpl.hp.com>, jbr...@hpl.hp.com (Jobst Brandt) writes:
>> Frank Krygowski writes:
>>
>> > As to the presence or absence of a "draft" in the direction of motion:
>> > If a jet plane were to fly by you at a distance of 10 feet, do you imagine
>> > you'd feel a wind blast _opposite_ the direction of the plane's travel,
>> > or _in_ the direction of the plane's travel? Or none at all?
>>
>
>2) Even though there is no net momentum behind the swimmer, there
>IS fore and aft motion at different locations. Just behind the
>swimmer's feet there is friction-caused forward motion which can
>be used for drafting. The balancing rearward motion is farther out
>to the sides and below, where the arms do most of the propelling.
>So a bad place to draft a swimmer is just a little off to the side.
>
>
>
> Mark Drela
> '
Mark,
Every time I read one of your responses, I learn a bunch. Thank you!
What about waves from swimmers next to each other? Commentators at
swimming meets blather about swimmers in adjacent lanes using the bow
wave from the swimmer slightly ahead to gain a slight advantage. Is
this possible?
JO
Jobst Brandt
Don Winston writes:
>> So how did you like the tubular offset due to glue?
> I plotted the data in Excel, and it makes a strong case for not
> riding tubulars. Jobst, do you have the data for hard and soft glue?
> Or at least the value of the offset?
We had no tires at the time that could be glued with track glue. For
that you need a "dry" non rubberized base tape. You probably noticed
that track tires have different base tape than road tires. I think
you'll find the curves you plotted to be solid proof of the rim glue
effect. You could even manipulate the curves by subtracting a
suitable constant from the tubular curves until they fit the family of
curves set up by clinchers. If you do that, the tubulars come in
below the others in RR just as you would expect of a tire that had
thinner tread, casing and tube.
I'm sorry we never tested the glues with the same track tire glued
with track and road glue, but the effort at the time these tests were
made was to show that smooth tread and specifically Avocet tires were
as good or better than other tires offered. Subsequently the
cornering photos were made showing riders at extreme banking angles on
wet and dry pavement.
Jobst Brandt <jbr...@hpl.hp.com>
rodr...@yahoo.com
In article <6f8o07$q...@ender.techcenter.paccar.com>,
jolsen wrote:
> What about waves from swimmers next to each other? Commentators at
> swimming meets blather about swimmers in adjacent lanes using the bow
> wave from the swimmer slightly ahead to gain a slight advantage. Is
> this possible?
>
> JO
Speaking as a swimmer... It's not that simple. Being in the "center lanes"
has other advantages.
1. In a short course pool (25 yards) you have many more turns. Turns create
alot of turbulence (mostly for yourself). Your position relative to the
swimmer in the next lane can be an issue, particularly in a sprint.
2. THE WALL. No one likes to swim against the wall. In some pools, the wall
lanes are not even assigned. The wall lanes reflect the waves from every
swimmer. You also have the psychological "hang up" of possibly striking an
elevated pool deck with your hand - - something no one else has to worry
about.
3. Also, the bow wave can modify the position of your body (raise your
torso). This is a big advantage to wetsuits. It supports you in a position
that you have not been trained to achieve (analagous to aerobars). Of course
the increased bouyancy is another big factor.
rr
-----== Posted via Deja News, The Leader in Internet Discussion ==-----
http://www.dejanews.com/ Now offering spam-free web-based newsreading
Mark Drela
In article <6f8o07$q...@ender.techcenter.paccar.com>, jol...@techcenter.paccar.com (John Olsen) writes:
> What about waves from swimmers next to each other? Commentators at
> swimming meets blather about swimmers in adjacent lanes using the bow
> wave from the swimmer slightly ahead to gain a slight advantage. Is
> this possible?
My description of the swimmer's wake neglected wave motion.
Even with the waves, the net wake momentum is still zero,
but the distribution of fore/aft motions is more complicated.
A swimmer can certainly extract power from the wave of the
swimmer ahead. At least in theory. The best place to "draft"
in a wave must be close to where your own right-going (say) wave
mostly cancels the right-going wave of the leading swimmer -- i'd
say about 1/2 body length ahead of the leading swimmer's "Mach cone".
By cancelling this wave, you are sucking off its energy which would
otherwise be dissipated against the sides of the pool. I have no
idea how much power can actually be transferred from one swimmer
to the other in this way.
The mechanism clearly doesn't exist for bikes, unless of course
they are going at supersonic speeds :-)
tku...@diabloresearch.com
In article <6f9kmt$q...@hplntx.hpl.hp.com>,
jbr...@hpl.hp.com (Jobst Brandt) wrote:
>
> If you do that, the tubulars come in
> below the others in RR just as you would expect of a tire that had
> thinner tread, casing and tube.
Lately I've had a dragging brake and was able to compare it's effect
on my performance compared to others in the group I've been in.
It would appear that even small changes in rolling resistance make
substantial changes in performance.
Do you have any actual figures for this performance change? Say,
comparisons of the performance for various tires that have known
rolling resistance. It seems like the perfect place for track testing.
Jobst Brandt
Tom Kunich writes:
> Lately I've had a dragging brake and was able to compare it's effect
> on my performance compared to others in the group I've been in.
> It would appear that even small changes in rolling resistance make
> substantial changes in performance.
I think that is a large jump to conclusion, having no measure of how
much energy a dragging brake absorbs in contrast to rolling resistance
of a tire.
> Do you have any actual figures for this performance change? Say,
> comparisons of the performance for various tires that have known
> rolling resistance. It seems like the perfect place for track testing.
Where have you been? Seeing that you are using dejanews, you shouldn't
have any trouble fetching the data files I posted on this subject.
Jobst Brandt <jbr...@hpl.hp.com>