Dear Jobst, Left-Hand Chain-Drive Details
Carl Fogel
In a recent email about a bicycle rear-wheel
text that you were asked to edit, you mentioned
that you dislike abbreviations like DS and NDS
for drive-side and non-drive-side.
When you suggested that right and left were
shorter, simpler, and just as good as DS and
NDS, I replied that I'd just seen an odd-looking
bike whose chain and gears were on the left.
(I call them gear-side and no-gear-side because
my rear wheel is usually upside-down when I'm
looking at it, so right and left are reversed.
God knows what we'd call one of the old-style
reversible rear wheels with a large climbing
cog on one side and a small high-speed cog on
the other.)
Anyway, here's a site that mentions the odd
left-side drive that I saw:
http://www.bmx-test.com/cgi-bin/reviews.cgi?review_id=745
I expect that all my nieces and nephews know
this stuff, but we don't seem to get a lot of
BMX threads in rec.bicycles.tech. I went back
to the Great Divide bike shop in Pueblo, Colorado,
and here's what I learned from the cheerful
mechanics.
On single-speed freewheel BMX bikes, some riders
doing tricks and stunts "grind" better one one
side or the other, so companies like Profile
and Primo have found a market in recent years
for wrong-side chains-and-gears that attach
on the left.
(Think of left-handed guitars and golf clubs.)
The local bike shop mechanics happily showed
me a catalogue listing the Profile SS Cassette
HU-1144, sold in right-hand and left-hand versions.
They pulled out a single-gear rear-cassette,
clearly marked "left" and showed me how it
freewheels one way, while its normal mate
(with no marking) freewheels the other way.
Even more interesting, they showed me how
pedal arms from Primo and Profile are sold
as mirror images, each equally capable of
mounting a front chain ring.
If the whole crank assembly were simply
reversed to install on the wrong side,
the traditional left-and-right-thread
pedals would tend to loosen.
To avoid this, the mounting holes and
massive braces appear on both left and
right pedal arms, allowing them to stay
on the correct side while just the chain
ring moves over to the wrong side.
It's a bit like the godless modern trend
in pistols, where safety-catches, slide
releases, and de-cockers can be put on
either side for the convenience of
left-handed heathens.
See you around the Leftorium,
Ned Flanders
Tom Sherman
Carl Fogel wrote:
> ...
> Anyway, here's a site that mentions the odd
> left-side drive that I saw:
>
> http://www.bmx-test.com/cgi-bin/reviews.cgi?review_id=745
>
> I expect that all my nieces and nephews know
> this stuff, but we don't seem to get a lot of
> BMX threads in rec.bicycles.tech. I went back
> to the Great Divide bike shop in Pueblo, Colorado,
> and here's what I learned from the cheerful
> mechanics.
>
> On single-speed freewheel BMX bikes, some riders
> doing tricks and stunts "grind" better one one
> side or the other, so companies like Profile
> and Primo have found a market in recent years
> for wrong-side chains-and-gears that attach
One could mount these left-hand drive components on the right-hand side
of the bike, and then pedal backwards. ;)
Tom Sherman - Planet Earth
Ted Bennett
You could do that, but it would be a lot simpler to just use a fixed
gear. Plus you could still pedal forwards.
--
Ted Bennett
Portland OR
Tom Sherman
Ted Bennett wrote:
>
> > One could mount these left-hand drive components on the right-hand side
> > of the bike, and then pedal backwards. ;)
> >
> > Tom Sherman - Planet Earth
>
> You could do that, but it would be a lot simpler to just use a fixed
> gear. Plus you could still pedal forwards.
There was a device making the bike show rounds a few years back that
turned the chainrings forward when pedaled either forwards or backwards.
The internal friction when pedaling backwards was quite noticeable and I
suspect the device was quite heavy also. An answer to a question almost
no one was asking, I suspect.
Chalo
> One could mount these left-hand drive components on the right-hand
> side of the bike, and then pedal backwards. ;)
I have considered the ultimate purpose of these parts, since they made
their appearance, to enable the construction of a symmetrical bike
with two drivetrains. (The LHD cassette hubs would be no good for
this; only an RH/LH freewheel hub would do.)
That, in addition to being cool and single-fault-tolerant, would fix
the left-crank loosening problem Jobst Brandt has identified and the
asymmetrical frame flex Sheldon Brown has described.
Chalo Colina
Gary Smiley
"You have two hemispheres in your brain - a left and a right side. The
left side controls the right side of your body and right controls the
left half. It's a fact. Therefore, left-handers are the only people in
their right minds."
Jeff Wills
It's been done. I remember seeing it in a BMX magazine ummm... many,
many years ago. The difficulty is getting both freewheels to engage
simultaneously. I believe the manufacturer machined up a special
two-sided cassette hub that insured both side's pawls lined up. The
manufacturer was asking $300 to $400 for the rear hub alone, IIRC.
The ads featured the builder's twin daughters, who apparently raced
with this system. I have no idea what their results were...
Jeff
AndyMorris
>
> Anyway, here's a site that mentions the odd
> left-side drive that I saw:
>
> http://www.bmx-test.com/cgi-bin/reviews.cgi?review_id=745
>
A while ago there was a pursuiter who had double sided drive.
One side was a fixed gear, the other was a freewheel with a larger sprocket.
He started with the fixed gear only just engaged with its thread.
By doing this the rider enjoyed a lower gear, using the freewheel, for the
first few pedal strokes until the fixed gear hit the end of its thread that
would become the driving gear and the freewheel would start freewheeling.
--
Andy Morris
AndyAtJinkasDotFreeserve.Co.UK
Love this:
Put an end to Outlook Express's messy quotes
http://home.in.tum.de/~jain/software/oe-quotefix/
jobst....@stanfordalumni.org
>> Anyway, here's a site that mentions the odd
>> left-side drive that I saw:
>> http://www.bmx-test.com/cgi-bin/reviews.cgi?review_id=745
> A while ago there was a pursuiter who had double sided drive.
> One side was a fixed gear, the other was a freewheel with a larger
> sprocket. He started with the fixed gear only just engaged with its
> thread.
> By doing this the rider enjoyed a lower gear, using the freewheel,
> for the first few pedal strokes until the fixed gear hit the end of
> its thread that would become the driving gear and the freewheel
> would start freewheeling.
That may be, but all sorts of two speed devices have been tried and
found useless. Even the best funded record attempts have not used
them. The best gear in which to start is the one in which you plan to
ride. This is true not only on the track but also on the road,
assuming the rider does not have a physical hindrance.
Humans are not Peterbilt trucks that do better going through many
gears to get up to speed. Gears on road bicycles are for climbing
long hills, not for starting from a stop sign. Nevertheless, there
are riders who shift down for stops on the flat and run through the
gears. I believe, had they ridden with other bikies on a casually
competitive basis they would have ;earned that they are at a
disadvantage in their method.
> http://home.in.tum.de/~jain/software/oe-quotefix/
Done that!
Jobst Brandt
jobst....@stanfordalumni.org
Ryan Cousineau
jobst....@stanfordalumni.org wrote:
Really? Few competitive road cycling events (this excludes track
oddities like the kilo, which are mandated as fixed-gear, singlespeed
anyways) put any significant emphasis on the start. Virtually all road
races, from the lowliest crit on upwards, have essentially neutral
starts. Only in short TTs (think prologue length) is the start enough of
a factor to really bother with.
But I commute to work, where for various reasons the stoplight grands
prix are regular features of my ride. I'm pretty sure after repeated
trials that I can usually accelerate from a stop to cruising speed
faster by starting 2-4 gears below my cruising ratio, and that's on my
slow-shifting DT-equipped bike. On the brifteur race bike, I happily
drag-race cars, something not easily accomplished starting from the big
gear.
In general, it feels like that first spin or two up to speed takes
forever in a big gear.
I'll have to watch carefully in my next MTB race. There, because of the
usual short sprint to enter the singletrack trails, a fast start is a
definite advantage. I can tell you two things: I usually outsprint
better dirt-riders, and I usually shift a few times getting up to speed.
I will evaluate my technique and that of fellow racers next race.
--
Ryan Cousineau, rcou...@sfu.ca http://www.sfu.ca/~rcousine
President, Fabrizio Mazzoleni Fan Club
Carl Fogel
Dear Jobst,
Am I correct in hoping that your suggestion
that "The best gear in which to start is the
one in which you plan to ride" was not meant
to apply to carbon-based life-forms that diesel
happily along in 53 x 11, both up and down the
Arkansas River, at 20-25 mph and 50-60 rpm?
Weird as I am, it's going to take a remarkably
convincing argument for me to stop shifting down
at that stupid traffic light and try to start out
from a dead stop in high gear.
Come to think of it, don't human strides start
off at walking length and then increase as they
start trotting and then widen even further as
they begin to run?
Carl Fogel
David L. Johnson
> Am I correct in hoping that your suggestion that "The best gear in which
> to start is the one in which you plan to ride" was not meant to apply to
> carbon-based life-forms that diesel happily along in 53 x 11, both up and
> down the Arkansas River, at 20-25 mph and 50-60 rpm?
Why on earth would you ride along on the flats in such a gear, anyway?
> Weird as I am, it's going to take a remarkably convincing argument for me
> to stop shifting down at that stupid traffic light and try to start out
> from a dead stop in high gear.
How 'bout an argument to not cruise in such a gear to begin with?
--
David L. Johnson
__o | There is always an easy solution to every human problem - neat,
_`\(,_ | plausible, and wrong. --H.L. Mencken
(_)/ (_) |
Ron Hardin
>
> > One side was a fixed gear, the other was a freewheel with a larger
> > sprocket. He started with the fixed gear only just engaged with its
> > thread.
>
> > By doing this the rider enjoyed a lower gear, using the freewheel,
> > for the first few pedal strokes until the fixed gear hit the end of
> > its thread that would become the driving gear and the freewheel
> > would start freewheeling.
It doesn't lower the gear if the fixed gear slips, it just reduces the
force applied to the wheel. If he were starting up a hill, the bike
would go backwards when he was pedalling forwards, which no gearing
does.
--
Ron Hardin
rhha...@mindspring.com
On the internet, nobody knows you're a jerk.
Ron Hardin
>
> > > A while ago there was a pursuiter who had double sided drive.
> >
> > > One side was a fixed gear, the other was a freewheel with a larger
> > > sprocket. He started with the fixed gear only just engaged with its
> > > thread.
> >
> > > By doing this the rider enjoyed a lower gear, using the freewheel,
> > > for the first few pedal strokes until the fixed gear hit the end of
> > > its thread that would become the driving gear and the freewheel
> > > would start freewheeling.
>
> It doesn't lower the gear if the fixed gear slips, it just reduces the
> force applied to the wheel. If he were starting up a hill, the bike
> would go backwards when he was pedalling forwards, which no gearing
> does.
Oh I see, the freewheel is preventing that.
dianne_1234
<AndyM...@DeadSpam.com> wrote:
>Carl Fogel wrote:
>>
>> Anyway, here's a site that mentions the odd
>> left-side drive that I saw:
>>
>> http://www.bmx-test.com/cgi-bin/reviews.cgi?review_id=745
>>
>
>A while ago there was a pursuiter who had double sided drive.
>
>One side was a fixed gear, the other was a freewheel with a larger sprocket.
>He started with the fixed gear only just engaged with its thread.
>
>By doing this the rider enjoyed a lower gear, using the freewheel, for the
>first few pedal strokes until the fixed gear hit the end of its thread that
>would become the driving gear and the freewheel would start freewheeling.
Former kilo world record holder Shaun Wallace. It really worked!
Brilliant!
Only one small detail: both chains were on the same side of the bike.
That way the fixed gear would advance on its threads. Also
conveniently hid the second chain unless you looked really closely!
The Canadian pursuiter (Lovell?) was the guy with the two-speed bike
that had one chain on each side. Not sure how that worked.
About 1981 Pinarello showed a Kilo bike with a chain on each side.
IIRC, it wasn't for two speeds, but for frame stiffness. I might have
misunderstood it, but at the time my impression was that after the
first 2.5 crank revolutions or so, the left side master link passed a
trigger pin on the downtube that disconnected it. After about another
2 turns turns of the crank the chain eventually fell off onto the
track, to be left behind. The right side chain remained to finish the
race.
Also, don't Aussie track riders run the chain on the left side always?
Dietrich Wiegmann
> In article <wF8Eb.3380$XF6....@typhoon.sonic.net>,
> jobst....@stanfordalumni.org wrote:
>
> > Andy Morris writes:
> >
> > > By doing this the rider enjoyed a lower gear, using the freewheel,
> > > for the first few pedal strokes until the fixed gear hit the end of
> > > its thread that would become the driving gear and the freewheel
> > > would start freewheeling.
> >
> > That may be, but all sorts of two speed devices have been tried and
> > found useless. Even the best funded record attempts have not used
> > them. The best gear in which to start is the one in which you plan to
> > ride. This is true not only on the track but also on the road,
> > assuming the rider does not have a physical hindrance.
>
> oddities like the kilo, which are mandated as fixed-gear, singlespeed
> anyways) put any significant emphasis on the start. Virtually all road
> races, from the lowliest crit on upwards, have essentially neutral
> starts. Only in short TTs (think prologue length) is the start enough of
> a factor to really bother with.
>
corner. 2 speed systems for BMX were tried and abandoned in the early
1980s.
Dietrich Wiegmann
Carl Fogel
> On Wed, 17 Dec 2003 22:39:54 +0000, Carl Fogel wrote:
>
> > Am I correct in hoping that your suggestion that "The best gear in which
> > to start is the one in which you plan to ride" was not meant to apply to
> > carbon-based life-forms that diesel happily along in 53 x 11, both up and
> > down the Arkansas River, at 20-25 mph and 50-60 rpm?
>
> Why on earth would you ride along on the flats in such a gear, anyway?
>
> > Weird as I am, it's going to take a remarkably convincing argument for me
> > to stop shifting down at that stupid traffic light and try to start out
> > from a dead stop in high gear.
>
> How 'bout an argument to not cruise in such a gear to begin with?
Dear David,
So why not?
Carl Fogel
Sheldon Brown
it's fun but it's hard to make myself pick it up from the right side to
carry it over the stairs.
I bought some Sugino AT tandem cranks on the Internet, with this in
mind. I'm running my usual 42/15 fixed gear.
I still haven't gotten used to how the bike looks, and it feels weird to
tuck my _left_ trouser leg into my sock, instead of my right one!
Quoth Jobst Brandt:
> ...The best gear in which to start is the one in which you plan to
> ride. This is true not only on the track but also on the road,
> assuming the rider does not have a physical hindrance.
I'm a bit schizophrenic about this. I mostly ride fixed-gear, where
this is a non-issue, but, when I _do_ ride on multispeed bikes, I'm a
constant shifter, and tend to maintain my cadence within a very narrow
range.
> Humans are not Peterbilt trucks that do better going through many
> gears to get up to speed. Gears on road bicycles are for climbing
> long hills, not for starting from a stop sign. Nevertheless, there
> are riders who shift down for stops on the flat and run through the
> gears. I believe, had they ridden with other bikies on a casually
> competitive basis they would have ;earned that they are at a
> disadvantage in their method.
This may well be true for old-fashioned frame-mounted shifters, but not
so for those of us who have our shift controls on the handlebars.
Reaching down to the down tube does have a cost of perhaps half a
stroke's worth of power, but this is not the case with handlebar-mounted
shifters.
I know how fond you are of the "Peterbuilt" schtick, but this is a case
of "reasoning by ridicule." You have never, so far as I know, presented
any evidence to suggest that shifting this way is not beneficial to the
cyclist who is interested in conserving energy and strain.
I do know that, in my own experience, when I run through a bunch of
gears as I leave a stop light, I leave most cyclists (and many cars) in
the dust for the first half block, even cylcists who are otherwise much
stronger and faster than a 59 year old fat guy like myself.
I do this partly because it's fun, and partly because I feel it is safer
to clear the intersection as promptly as possible, to avoid the crush of
traffic.
Sheldon "Never Liked Downtube Shifters" Brown
+----------------------------------------------------------------------+
| I am come-in a very moralizing strain, to observe that our |
| pleasures in this world are always to be paid for, and that we |
| often purchase them at a great disadvantage, giving ready-monied |
| actual happiness for a draft on the future, that may not be honored. |
| -- Henry Tilney, Northanger Abbey by Jane Austen |
+----------------------------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com
jobst....@stanfordalumni.org
> Am I correct in hoping that your suggestion that "The best gear in
> which to start is the one in which you plan to ride" was not meant
> to apply to carbon-based life-forms that diesel happily along in 53
> x 11, both up and down the Arkansas River, at 20-25 mph and 50-60
> rpm?
Your choice of gear tells me that you ride at less than the speeds you
suggest. 50-60 rpm would give 18.8-22.6 mph with an average size
wheel. I think you ought to get into TT racing if you can pull that
off in such a gear. I haven't seen anyone riding that fast on the
flats in anywhere near that gear, but there may be exceptional riders
that I have overlooked.
> Weird as I am, it's going to take a remarkably convincing argument
> for me to stop shifting down at that stupid traffic light and try to
> start out from a dead stop in high gear.
Yes and it will take even more to convince riders that turning their
bicycle upside down to take the rear wheel out and repair a flat is
not useful.
> Come to think of it, don't human strides start off at walking length
> and then increase as they start trotting and then widen even further
> as they begin to run?
There go those question marks... again.
Jobst Brandt
jobst....@stanfordalumni.org
jobst....@stanfordalumni.org
> This may well be true for old-fashioned frame-mounted shifters, but
> not so for those of us who have our shift controls on the
> handlebars.
> Reaching down to the down tube does have a cost of perhaps half a
> stroke's worth of power, but this is not the case with
> handlebar-mounted shifters.
This makes it sound like there are a lot of gears top be shifted but
in reality I can't imagine more than two or three and not accelerating
at any notable rate, time between shifts is large. A parallel oddity
can be found in drag racing where speeds go from 0-300+mph in 4.4 sec.
http://www.nhra.com/stats/natrecord.html
in the same gear.
> I know how fond you are of the "Peterbuilt" schtick, but this is a
> case of "reasoning by ridicule." You have never, so far as I know,
> presented any evidence to suggest that shifting this way is not
> beneficial to the cyclist who is interested in conserving energy and
> strain.
Ahh. There's the catch, "energy and strain". As we get older, we
tend to avoid these. When was the last time you won a city limits
sprint? Those take energy and strain as do climbing over big hills
like Sonora Pass CA with its 20% grades at the summit... but can you
spell Peterbilt?
> I do know that, in my own experience, when I run through a bunch of
> gears as I leave a stop light, I leave most cyclists (and many cars) in
> the dust for the first half block, even cylcists who are otherwise much
> stronger and faster than a 59 year old fat guy like myself.
I guess traffic has changed. Around here, one of the best trackie
training tricks is to beat cars across the intersection when the light
turns green. It ain't easy and the cars aren't even competing. Of
course they have automatic transmissions, so that ain't fair.
> I do this partly because it's fun, and partly because I feel it is
> safer to clear the intersection as promptly as possible, to avoid
> the crush of traffic.
> Sheldon "Never Liked Downtube Shifters" Brown
I cheat and cross before the light changes if I can.
Jobst Brandt
jobst....@stanfordalumni.org
David Reuteler
: I guess traffic has changed. Around here, one of the best trackie
: training tricks is to beat cars across the intersection when the light
: turns green. It ain't easy and the cars aren't even competing. Of
: course they have automatic transmissions, so that ain't fair.
i do this numerous times on my commute (on my track bike) and usually "win."
trackstand for green and sprint for the ped xing. it is a lot of fun.
actually i'm on your side on this one .. maybe it's the track bike but even
on my road bike i rarely shift down for intersections. dunno if it can't
help, tho. seems 1 or 2 shifts might be beneficial.
you must have especially bad jack-rabbit traffic in cali, ey? or are you
getting soft?
--
david reuteler
reut...@visi.com
jobst....@stanfordalumni.org
>> I guess traffic has changed. Around here, one of the best trackie
>> training tricks is to beat cars across the intersection when the
>> light turns green. It ain't easy and the cars aren't even
>> competing. Of course they have automatic transmissions, so that
>> ain't fair.
> I do this numerous times on my commute (on my track bike) and
> usually "win." Trackstand for green and sprint for the ped xing.
> It is a lot of fun. Actually I'm on your side on this one .. maybe
> it's the track bike but even on my road bike I rarely shift down for
> intersections. Dunno if it can't help, tho. Seems 1 or 2 shifts
> might be beneficial.
> You must have especially bad jack-rabbit traffic in cali, ey? Or
> are you getting soft?
We have 4 to 6 lane expressways with center dividers to cross so it
isn't easy to beat cars but it's still close.
Jobst Brandt
jobst....@stanfordalumni.org
David Reuteler
: we have 4 to 6 lane expressways with center dividers to cross so it
: isn't easy to beat cars but it's still close.
maybe i can hire you? ;-)
--
david reuteler
reut...@visi.com
Sheldon Brown
>>This may well be true for old-fashioned frame-mounted shifters, but
>>not so for those of us who have our shift controls on the
>>handlebars.
>
>
>>Reaching down to the down tube does have a cost of perhaps half a
>>stroke's worth of power, but this is not the case with
>>handlebar-mounted shifters.
Jobst replied:
> This makes it sound like there are a lot of gears top be shifted but
> in reality I can't imagine more than two or three and not accelerating
> at any notable rate, time between shifts is large.
With close ratio gearing, time between shifts is brief.
> A parallel oddity
> can be found in drag racing where speeds go from 0-300+mph in 4.4 sec.
>
> http://www.nhra.com/stats/natrecord.html
>
> in the same gear.
Drag racing is mostly done with the tires spinning, isn't it? I don't
think that bears much relation to anything in cycling.
>>I know how fond you are of the "Peterbuilt" schtick, but this is a
>>case of "reasoning by ridicule." You have never, so far as I know,
>>presented any evidence to suggest that shifting this way is not
>>beneficial to the cyclist who is interested in conserving energy and
>>strain.
>
>
> Ahh. There's the catch, "energy and strain". As we get older, we
> tend to avoid these. When was the last time you won a city limits
> sprint?
I've never been into those, and don't like to ride with folks who do that.
I'm not a competition-oriented cyclist.
> Those take energy and strain as do climbing over big hills
> like Sonora Pass CA with its 20% grades at the summit...
Never been there.
> but can you spell Peterbilt?
Touché
Sheldon "Sometimes Shifty, Sometimes Fixed" Brown
+---------------------------------------------------+
| Absurdity, n.: A statement or belief manifestly |
| inconsistent with one's own opinion. |
| --Ambrose Bierce, "The Devil's Dictionary" |
+---------------------------------------------------+
AndyMorris
> On Thu, 18 Dec 2003 00:51:14 -0000, "AndyMorris"
> <AndyM...@DeadSpam.com> wrote:
>
>> Carl Fogel wrote:
>>>
>>> Anyway, here's a site that mentions the odd
>>> left-side drive that I saw:
>>>
>>> http://www.bmx-test.com/cgi-bin/reviews.cgi?review_id=745
>>>
>>
>> A while ago there was a pursuiter who had double sided drive.
>>
>> One side was a fixed gear, the other was a freewheel with a larger
>> sprocket. He started with the fixed gear only just engaged with its
>> thread.
>>
>> By doing this the rider enjoyed a lower gear, using the freewheel,
>> for the first few pedal strokes until the fixed gear hit the end of
>> its thread that would become the driving gear and the freewheel
>> would start freewheeling.
>
> Former kilo world record holder Shaun Wallace. It really worked!
> Brilliant!
>
> Only one small detail: both chains were on the same side of the bike.
> That way the fixed gear would advance on its threads. Also
> conveniently hid the second chain unless you looked really closely!
>
> The Canadian pursuiter (Lovell?) was the guy with the two-speed bike
> that had one chain on each side. Not sure how that worked.
>
The one I remember definatly had a cahin each side, must of been in the mid
80's. And he was a pursuiter, must of been Lovell.
ISTR that the extra weight just about canceled out the advantage.
Carl Fogel
Dear Jobst,
Given speedometer readings of 20-25mph,
my spreadsheet indicates a cadence on a
typical 700c wheel of 52.42-65.52 rpm
with my 53 x 11, not the mere 50-60 of
my offhand estimate.
Gracious, nearly 66 rpm! I must be really
spinning! Look out, Lance!
Do you advise starting out from a dead
stop on level pavement in 53 x 11? I
seem to get faster results starting out
in lower gears and shifting up, even with
my pathetically out-dated friction shifters.
Asking questions is often better than
avoiding them, don't you agree? For
all I know, you may have a sound
explanation for the notion that
using a single high gear is as good
as shifting up through a range in
starting out on a level ride.
I hope to get it before the 25th.
Merry Christmas!
Carl Fogel
jobst....@stanfordalumni.org
>>> This may well be true for old-fashioned frame-mounted shifters,
>>> but not so for those of us who have our shift controls on the
>>> handlebars.
>>> Reaching down to the down tube does have a cost of perhaps half a
>>> stroke's worth of power, but this is not the case with
>>> handlebar-mounted shifters.
>> This makes it sound like there are a lot of gears top be shifted
>> but in reality I can't imagine more than two or three and not
>> accelerating at any notable rate, time between shifts is large.
> With close ratio gearing, time between shifts is brief.
>> A parallel oddity can be found in drag racing where speeds go from
>> 0-300+mph in 4.4 sec.
>> http://www.nhra.com/stats/natrecord.html
>> in the same gear.
> Drag racing is mostly done with the tires spinning, isn't it? I
> don't think that bears much relation to anything in cycling.
Not so. When you see white smoke during a run, the guy must shut off.
Wheel spin is a no no for drag racing. There are no gears, real or
otherwise.
>>> I know how fond you are of the "Peterbuilt" schtick, but this is a
>>> case of "reasoning by ridicule." You have never, so far as I know,
>>> presented any evidence to suggest that shifting this way is not
>>> beneficial to the cyclist who is interested in conserving energy and
>>> strain.
>> Ahh. There's the catch, "energy and strain". As we get older, we
>> tend to avoid these. When was the last time you won a city limits
>> sprint?
> I've never been into those, and don't like to ride with folks who do
> that. I'm not a competition-oriented cyclist.
>> Those take energy and strain as do climbing over big hills
>> like Sonora Pass CA with its 20% grades at the summit...
> Never been there.
Then I take it you were never an ABL or USCF bikie. Bicycling
competitively as a teenager and onward is a great start of bicycling.
It was only because we had so many bikies around here that I could get
reasonable Sunday rides on the road. They thought I was taking them
on a training ride but in fact they were great tours throughout the
Santa Cruz Mountains and East (SF) Bay Hills. Lots of city, county
and even state limits to sprint for.
Many of these guys showed up for some great old farts rides for the
65th birthday of Nick Ferac-ban the Bike Barb of yore, 40 Years
Velo-Sport Cyclery (Peter Rich) and Dave Prion's wedding for which we
took a classic Sunday ride on pavement and trail with the greatest
dirt and pavement descenders I've seen in a long while. These guys
don't shift all the time either.
Jobst Brandt
jobst....@stanfordalumni.org
Jeff Wills
<snip>
> in reality I can't imagine more than two or three and not accelerating
> at any notable rate, time between shifts is large. A parallel oddity
> can be found in drag racing where speeds go from 0-300+mph in 4.4 sec.
>
> http://www.nhra.com/stats/natrecord.html
>
> in the same gear.
That's not a good analogy. While Top Fuel cars use a single gear,
they also have multi-stage slipper clutches. The clutch slips a set
amount at the start, slips less at the middle of the run, and locks up
completely at the end. This is all controlled by a
mechanical-over-pneumatic timing system, electronic clutch management
being prohibited by the NHRA.
Multi-stage clutch tuning has risen to the same level as fuel
injection tuning in the top levels of drag racing. IIRC, clutch
technology is largely credited with lowering the 1/4 mile records from
the 5.0 to the 4.4 second range.
FWIW: I've been using a single-speed junker to get around town. In
general I get through intersections quicker than most of the other
commuters. I think Jobst's original point is valid with a little
modification: many people don't need all the gears that are delivered
on modern bikes.
Jeff
Jeff Wills
> > A parallel oddity
> > can be found in drag racing where speeds go from 0-300+mph in 4.4 sec.
> >
> > http://www.nhra.com/stats/natrecord.html
> >
> > in the same gear.
>
> Drag racing is mostly done with the tires spinning, isn't it? I don't
> think that bears much relation to anything in cycling.
Not since the '60's. Since then, it's largely a process of heating
the tires enough to glue them to the track. Top Fuel launches
generate 4 to 5 G's of acceleration.
We *are* wandering a bit off topic, aren't we?
Jeff the Irrelevant
jobst....@stanfordalumni.org
>>> Am I correct in hoping that your suggestion that "The best gear in
>>> which to start is the one in which you plan to ride" was not meant
>>> to apply to carbon-based life-forms that diesel happily along in
>>> 53 x 11, both up and down the Arkansas River, at 20-25 mph and
>>> 50-60 rpm?
>> Your choice of gear tells me that you ride at less than the speeds
>> you suggest. 50-60 rpm would give 18.8-22.6 mph with an average
>> size wheel. I think you ought to get into TT racing if you can
>> pull that off in such a gear. I haven't seen anyone riding that
>> fast on the flats in anywhere near that gear, but there may be
>> exceptional riders that I have overlooked.
>>> Weird as I am, it's going to take a remarkably convincing argument
>>> for me to stop shifting down at that stupid traffic light and try
>>> to start out from a dead stop in high gear.
>> Yes and it will take even more to convince riders that turning
>> their bicycle upside down to take the rear wheel out and repair a
>> flat is not useful.
>>> Come to think of it, don't human strides start off at walking
>>> length and then increase as they start trotting and then widen
>>> even further as they begin to run?
>> There go those question marks... again.
> Given speedometer readings of 20-25mph, my spreadsheet indicates a
> cadence on a typical 700c wheel of 52.42-65.52 rpm with my 53 x 11,
> not the mere 50-60 of my offhand estimate.
The point is that that is pretty stiff riding and should enable you to
drop many riders on the flats and hills if you actually rode such
speeds for longer than to capture a max speed reading. The
calculations I made above are accurate based on 50-60rpm.
> Gracious, nearly 66 rpm! I must be really spinning! Look out, Lance!
> Do you advise starting out from a dead stop on level pavement in
> 53x11? I seem to get faster results starting out in lower gears and
> shifting up, even with my pathetically out-dated friction shifters.
I doubt that anyone would advise that gear for anything but closing a
gap, downhill or with a strong tailwind. Just because they are
available doesn't make them useful gears. In fact riders who think
pedaling at speeds over 30mph when descending is useful are fooling
themselves. You can compute the extra power required to increase
speed from 30 to 31mph and see that it is a huge jump. I often coast
by people who think that just because they have an 11t sprocket that
it will help them go faster.
> Asking questions is often better than avoiding them, don't you
> agree? For all I know, you may have a sound explanation for the
> notion that using a single high gear is as good as shifting up
> through a range in starting out on a level ride.
Those who do it know why. The continuity of effort is far more
important than changing rate and force on the pedals. When climbing,
shifting is one of the most difficult decisions because regardless of
which direction is needed, the change in cadence and force hurts.
Neither of them want to have a step function. Shifting invariably
slows speed if it is done when near the limit of effort.
> I hope to get it before the 25th.
Santa can't ride worth a damn. To heavy.
Jobst Brandt
jobst....@stanfordalumni.org
jobst....@stanfordalumni.org
>> This makes it sound like there are a lot of gears top be shifted
>> but in reality I can't imagine more than two or three and not
>> accelerating at any notable rate, time between shifts is large. A
>> parallel oddity can be found in drag racing where speeds go from
>> 0-300+mph in 4.4 sec.
>> http://www.nhra.com/stats/natrecord.html
>> in the same gear.
> That's not a good analogy. While Top Fuel cars use a single gear,
> they also have multi-stage slipper clutches. The clutch slips a set
> amount at the start, slips less at the middle of the run, and locks
> up completely at the end. This is all controlled by a
> mechanical-over-pneumatic timing system, electronic clutch
> management being prohibited by the NHRA.
There is only one gear. Torque ratio between engine and wheels is
constant. A clutch can only throw away power, and at at more than
1000HP I cant imagine that there is much slip. The slip is mainly for
suppressing wheel slip which immediately breaks traction as tire
rubber melts and becomes a lubricant.
> Multi-stage clutch tuning has risen to the same level as fuel
> injection tuning in the top levels of drag racing. IIRC, clutch
> technology is largely credited with lowering the 1/4 mile records
> from the 5.0 to the 4.4 second range.
I think you'll find that there isn't a lot of slip going on in these
events. In fact, if you stand at the starting line, you'll notice
that there is no change in pitch (RPM) discernable as the car goes
down the strip. That is because as the RPM increase, speed also does,
so the speed shifted exhaust note reaches the observer at a constant
frequency. Any significant slip would appear as a change in tone.
Pop juice produces an explosive exhaust similar to 50cal machine gun
except louder and faster.
> FWIW: I've been using a single-speed junker to get around town. In
> general I get through intersections quicker than most of the other
> commuters. I think Jobst's original point is valid with a little
> modification: many people don't need all the gears that are
> delivered on modern bikes.
That means you are still kicking... not retired yet.
Jobst Brandt
jobst....@stanfordalumni.org
Peter
> Jeff Wills <jwi...@pacifier.com> writes:
>
>>Multi-stage clutch tuning has risen to the same level as fuel
>>injection tuning in the top levels of drag racing. IIRC, clutch
>>technology is largely credited with lowering the 1/4 mile records
>>from the 5.0 to the 4.4 second range.
>
>
> I think you'll find that there isn't a lot of slip going on in these
> events. In fact, if you stand at the starting line, you'll notice
> that there is no change in pitch (RPM) discernable as the car goes
> down the strip. That is because as the RPM increase, speed also does,
> so the speed shifted exhaust note reaches the observer at a constant
> frequency.
If true, I'd view this as experimental evidence in favor of substantial
slippage. Doppler-effect decreases in frequency due to the increasing
speed would not be sufficient to overcome the rising frequency due to
increasing engine RPM. For example, in going from 50 mph to 250 mph, the
Doppler effect would result in a decrease in apparent frequency of about
20%. But the engine RPM, without any gearing changes or slippage, would
increase by a factor of 5. So the perceived frequency should increase by a
factor of .8 * 5 = 4. If it actually remains constant there must be a much
higher RPM than expected at the 50 mph speed - presumably due to clutch
slip if the wheels aren't slipping and there's no variable gearing.
This has gotten very far afield from bicycle technology. Frankly I'm
surprised you raise the drag-racing analogy. Unlike drag-racers,
bicyclists have very low power/weight ratios and more closely resemble the
Peterbilt in this respect. OTOH, cyclists have very high low-speed torque
which allows the use of fairly high gears at start-up. Personally I'm not
concerned about getting the last bit of speed on my way between stop
lights, but I do find it more comfortable to make one or two shifts when
starting up rather than leaving the bike in the appropriate cruising-speed
gear.
Sheldon Brown
>>>>I know how fond you are of the "Peterbuilt" schtick, but this is a
>>>>case of "reasoning by ridicule." You have never, so far as I know,
>>>>presented any evidence to suggest that shifting this way is not
>>>>beneficial to the cyclist who is interested in conserving energy and
>>>>strain.
Jobst replied:
>>>Ahh. There's the catch, "energy and strain". As we get older, we
>>>tend to avoid these. When was the last time you won a city limits
>>>sprint?
>
>>I've never been into those, and don't like to ride with folks who do
>>that. I'm not a competition-oriented cyclist.
>
>>>Those take energy and strain as do climbing over big hills
>>>like Sonora Pass CA with its 20% grades at the summit...
>
>>Never been there.
>
>
> Then I take it you were never an ABL or USCF bikie.
Nope. I was an AYH and LAW bikie.
> Bicycling
> competitively as a teenager and onward is a great start of bicycling.
That's true if you approach cycling as a competitive sport. I don't.
For me it's about recreation and transportation.
> It was only because we had so many bikies around here that I could get
> reasonable Sunday rides on the road. They thought I was taking them
> on a training ride but in fact they were great tours throughout the
> Santa Cruz Mountains and East (SF) Bay Hills. Lots of city, county
> and even state limits to sprint for.
I don't "train."
>
> Many of these guys showed up for some great old farts rides for the
> 65th birthday of Nick Ferac-ban the Bike Barb of yore,
I usedta love reading him in the old Competitive Cycling, though I've
never been a competitive cyclist.
> 40 Years
> Velo-Sport Cyclery (Peter Rich) and Dave Prion's wedding for which we
> took a classic Sunday ride on pavement and trail with the greatest
> dirt and pavement descenders I've seen in a long while. These guys
> don't shift all the time either.
I've generally observed that racing cyclists are not very into the fine
points of gearing. That's an area of cycling where touring cyclist are
generally more knowledgeable.
Racing is a small, relatively unimportant subset of the cycling world.
I have a small degree of interest in it as a spectator sport, but it's
really not my thing.
Sheldon "I Wait For Slower Riders, Expect Faster Friends To Wait For Me"
Brown
+---------------------------------+
| Is ambivalence a bad thing? |
| Well, yes and no. |
| -- Garrison Keillor |
+---------------------------------+
jobst....@stanfordalumni.org
>>> Multi-stage clutch tuning has risen to the same level as fuel
>>> injection tuning in the top levels of drag racing. IIRC, clutch
>>> technology is largely credited with lowering the 1/4 mile records
>>> from the 5.0 to the 4.4 second range.
>> I think you'll find that there isn't a lot of slip going on in
>> these events. In fact, if you stand at the starting line, you'll
>> notice that there is no change in pitch (RPM) discernable as the
>> car goes down the strip. That is because as the RPM increase,
>> speed also does, so the speed shifted exhaust note reaches the
>> observer at a constant frequency.
> If true, I'd view this as experimental evidence in favor of
> substantial slippage. Doppler-effect decreases in frequency due to
> the increasing speed would not be sufficient to overcome the rising
> frequency due to increasing engine RPM. For example, in going from
> 50 mph to 250 mph, the Doppler effect would result in a decrease in
> apparent frequency of about 20%. But the engine RPM, without any
> gearing changes or slippage, would increase by a factor of 5. So
> the perceived frequency should increase by a factor of .8 * 5 = 4.
> If it actually remains constant there must be a much higher RPM than
> expected at the 50 mph speed - presumably due to clutch slip if the
> wheels aren't slipping and there's no variable gearing.
Now that I think about it further, the effect may have been that the
frequency doesn't shift as much as one would expect. The vehicle
reaching less than half the speed of sound could at best make the
engine seem as though it were turning half as fast as it is. The
effect is startling though, as is the appearance seen from behind the
starting line from which the car does not seem to depart as much as it
gives the appearance of a zoom lens reduction in size. I am no
accustomed to seeing large bodies depart at such rates.
> This has gotten very far afield from bicycle technology. Frankly
> I'm surprised you raise the drag-racing analogy. Unlike
> drag-racers, bicyclists have very low power/weight ratios and more
> closely resemble the Peterbilt in this respect.
I think there is another factor at work and that is the steam engine
principal that the greatest torque is at standstill and falls off with
speed. Somewhere in there is a maximum power rate that varies for
different riders, something that is overlooked by those who preach
an ideal cadence for all.
> OTOH, cyclists have very high low-speed torque which allows the use
> of fairly high gears at start-up. Personally I'm not concerned
> about getting the last bit of speed on my way between stop lights,
> but I do find it more comfortable to make one or two shifts when
> starting up rather than leaving the bike in the appropriate
> cruising-speed gear.
It depends on how willing you are to put high torque into the start.
Forceful pedaling is uncomfortable for many riders.
Jobst Brandt
jobst....@stanfordalumni.org
meb
> Ted Bennett wrote:
> >
> > > One could mount these left-hand drive components on the right-hand
> > > side of the bike, and then pedal backwards. ;)
> > >
> > > Tom Sherman - Planet Earth
> >
> > You could do that, but it would be a lot simpler to just use a fixed
> > gear. Plus you could still pedal forwards.
> There was a device making the bike show rounds a few years back that
> turned the chainrings forward when pedaled either forwards or backwards.
> The internal friction when pedaling backwards was quite noticeable and I
> suspect the device was quite heavy also. An answer to a question almost
> no one was asking, I suspect.
> Tom Sherman - Planet Earth
Sounds like PowerCranks. It's a training crank for training competition
athletes and injury rehabilitation. The left and right arms turn independently-
forward or back. Very popular with triathletes. It's more effective at
conditioning than fixed-arm cranks. Also being used on stationary bikes.
Upright cyclists and even NFL teams are using them for leg training.
Not something you'd use in a race. For touring and commuting you might
use them if training was a colateral objective.
--
Jeff Wills
> Jeff Wills <jwi...@pacifier.com> writes:
>
> >> This makes it sound like there are a lot of gears top be shifted
> >> but in reality I can't imagine more than two or three and not
> >> accelerating at any notable rate, time between shifts is large. A
> >> parallel oddity can be found in drag racing where speeds go from
> >> 0-300+mph in 4.4 sec.
>
> >> http://www.nhra.com/stats/natrecord.html
>
> >> in the same gear.
>
> > That's not a good analogy. While Top Fuel cars use a single gear,
> > they also have multi-stage slipper clutches. The clutch slips a set
> > amount at the start, slips less at the middle of the run, and locks
> > up completely at the end. This is all controlled by a
> > mechanical-over-pneumatic timing system, electronic clutch
> > management being prohibited by the NHRA.
>
> There is only one gear. Torque ratio between engine and wheels is
> constant. A clutch can only throw away power, and at at more than
> 1000HP I cant imagine that there is much slip. The slip is mainly for
> suppressing wheel slip which immediately breaks traction as tire
> rubber melts and becomes a lubricant.
>
Modern Top Fuel engines produce between 5,000 and 6,000 horsepower...
and there's enormous amounts of clutch slip in the first third of the
run. If you watch video of a TF start, you can see the puffs of
carbon fiber dust from the clutch.
*Of course* it's for suppressing wheel slip- but clutch slip also
allows the engine to make maximum power while not smoking the tires
(as you said) or setting up resonance in the sidewalls (tire shake).
Here's the output from a Top Fuel data logger:
http://www.plr.nu/images/graph.jpg
the black line show engine rpm and the dark blue line shows speed.
It's pretty apparent that engine RPM is nearly constant while the
vehicle is accelerating. With a single gear ratio, the only way to
accomplish this is through clutch slip.
Jeff
Ryan Cousineau
dwie...@anteon.com (Dietrich Wiegmann) wrote:
But don't BMXes already use really low gears? It's been a while since my
last ride on one, but they typically spin out at relatively low speeds,
presumbably because the speed around the track is limited more by
getting the jump timing right than by the maximum speed of the cyclist,
assuming reasonably small variations in rider power.
The parallel problem is that 2-speed systems are virtually impossible to
make as efficient as 1-speed systems, but don't fully offer the
multi-speed advantage. Once a BMX racer gets out of the gate, they have
to carry the 2-speed drivetrain around the track for the entire race, no
matter how useless it is beyond the first few feet.
--
Ryan Cousineau, rcou...@sfu.ca http://www.sfu.ca/~rcousine
President, Fabrizio Mazzoleni Fan Club
Carl Fogel
> Carl Fogel writes:
>
> >>> Am I correct in hoping that your suggestion that "The best gear in
> >>> which to start is the one in which you plan to ride" was not meant
> >>> to apply to carbon-based life-forms that diesel happily along in
> >>> 53 x 11, both up and down the Arkansas River, at 20-25 mph and
> >>> 50-60 rpm?
>
> >> Your choice of gear tells me that you ride at less than the speeds
> >> you suggest. 50-60 rpm would give 18.8-22.6 mph with an average
> >> size wheel. I think you ought to get into TT racing if you can
> >> pull that off in such a gear. I haven't seen anyone riding that
> >> fast on the flats in anywhere near that gear, but there may be
> >> exceptional riders that I have overlooked.
[snip Jobst explaining advantage of no-shift starting out]
Dear Jobst,
Alas, my high gearing, glacial cadence,
and ordinary speed seem to puzzle many
people who use lower gears and faster
cadences to reach higher speeds.
On the long flat stretches of my daily
ride, my speedometers have read 20-25
mph for years, calibrated to the measured
size of my front tire and checked against
landmarks and stopwatch.
It took me about 3:12 today, as usual,
from my driveway to a dead stop at the
stupid traffic light about 1.20 miles
away. That's an average of 22.5 mph
on flat ground from a standing start.
Given my age, weight, sloth, and bike,
I doubt that anything that I do would
be called "stiff riding" by serious
cyclists--who hardly exist in these
parts, a scarcity that explains some
of my ignorance.
In the first block, there are three
right-angle corners as I plod up to
speed, shifting gears. After that,
the only curves as I chug along are
a half roundabout and two modest
45-degree corners.
It's flat enough that most people
would wonder which way the water
runs in the gutters. It's also
nicely paved and sheltered by thick
trees that kill the wind.
I do enjoy the advantage of the
reduced wind drag at roughly 5,000
feet and face only a 15-mile daily
ride for fun.
I expect that a serious rider would:
a) use lower gears than 53 x 11
b) spin higher cadences than 52 to 66 rpm
c) go much farther than 15 miles per day
d) pedal much faster than 20-25mph on flats
But I don't know why lower gears and
brisker pedalling work better for such
riders. I'm so sluggish that it seems
to me that they must be doing more
work, raising their legs faster and so
many more times to cover the same mile.
If you have a higher-cadence explanation,
I hope that you can dumb it down for me.
Perhaps there's a slow-twitch diesel
in my family tree?
Carl Fogel
Andrew Bradley
> >> A while ago there was a pursuiter who had double sided drive.
> >>
> >> One side was a fixed gear, the other was a freewheel with a larger
> >> sprocket. He started with the fixed gear only just engaged with its
> >> thread.
> >>
> >> By doing this the rider enjoyed a lower gear, using the freewheel,
> >> for the first few pedal strokes until the fixed gear hit the end of
> >> its thread that would become the driving gear and the freewheel
> >> would start freewheeling.
> >
> > Former kilo world record holder Shaun Wallace. It really worked!
> > Brilliant!
> >
> > Only one small detail: both chains were on the same side of the bike.
> > That way the fixed gear would advance on its threads. Also
> > conveniently hid the second chain unless you looked really closely!
> >
> > The Canadian pursuiter (Lovell?) was the guy with the two-speed bike
> > that had one chain on each side. Not sure how that worked.
It worked on the same principle i believe. Lovell then went on to
break his neck IIRC. Anyone know how he is getting on?
> The one I remember definatly had a cahin each side, must of been in the mid
> 80's. And he was a pursuiter, must of been Lovell.
>
> ISTR that the extra weight just about canceled out the advantage.
Don't know about the weight. Anyone have figures for freewheel drag?
They are surely banned now anyway.
Despite what one of the greats claims they did address a real issue
which is that you can't get as much power at low pedal speed, so the
quicker you get up to cadence the better.
On the start line of bike races, most people will be in a big-big
combination (not necessarily the very biggest sprocket).
Firing through the gears during sprints is another thing that happens
nowadays(don't look Sheldon Brown!) so you can start the sprint in a
lower gear.
Andrew Bradley
Andrew Bradley
Andrey
> gap, downhill or with a strong tailwind. Just because they are
> available doesn't make them useful gears. In fact riders who think
> pedaling at speeds over 30mph when descending is useful are fooling
> themselves. You can compute the extra power required to increase
> speed from 30 to 31mph and see that it is a huge jump. I often coast
> by people who think that just because they have an 11t sprocket that
> it will help them go faster.
I think you not really Jobst Brandt, because you make such a gross error
declaration.
> > Asking questions is often better than avoiding them, don't you
> > agree? For all I know, you may have a sound explanation for the
> > notion that using a single high gear is as good as shifting up
> > through a range in starting out on a level ride.
>
> Those who do it know why. The continuity of effort is far more
> important than changing rate and force on the pedals. When climbing,
> shifting is one of the most difficult decisions because regardless of
> which direction is needed, the change in cadence and force hurts.
> Neither of them want to have a step function. Shifting invariably
> slows speed if it is done when near the limit of effort.
When climbing, Power Output is even more needed to monitor, than on flat
road. You "may-be-shifting-problems" announcements are ridiculous. You
really need the Polar with power meter. You will see, that maximum
transfered to wheel power is in limited 60-110 cadence range, so to start at
high gear is inefficient.
Dave Kahn
> Those who do it know why. The continuity of effort is far more
> important than changing rate and force on the pedals. When climbing,
> shifting is one of the most difficult decisions because regardless of
> which direction is needed, the change in cadence and force hurts.
> Neither of them want to have a step function. Shifting invariably
> slows speed if it is done when near the limit of effort.
These days there are a lot of utility riders on mountain bikes and
hybrids with a huge range of (mostly low) gears available. I notice
many of them starting out from traffic lights in absurdly low gears
and clearly riding at close to maximum effort. Although their
pedalling looks Chaplinesque they do in fact have impressive
acceleration over about the first 5 to 10 yards, but as they move up
through the ratios the effort tells and within about 30 yards they
start to drop back.
That said, the track bike set up with a left handed freewheel and an
almost unscrewed fixed is an ingenious idea for providing one fully
automatic gear change early in the ride. I don't think you could just
rule out the idea that it might provide an advantage without at least
testing it. The inital acceleration at least has to be better. The
question is whether the cost of the gear change and the slight
increase in weight wipe out that initial advantage. Whether it's track
legal is another matter.
--
Dave...
David Damerell
>actually i'm on your side on this one .. maybe it's the track bike but even
>on my road bike i rarely shift down for intersections. dunno if it can't
>help, tho. seems 1 or 2 shifts might be beneficial.
1 shift is one thing - hell, if I'm riding in the 52x18 I shift down into
the 21, but if I'm riding in the 21 I just stick with it - but sometimes
one sees people making 3 or 4 or more. I've even seen people on
pseudo-MTBs _front_ shifting at lights, which is clearly pointless because
they can't push hard during a front shift.
--
David Damerell <dame...@chiark.greenend.org.uk> flcl?
Scott Hendricks
> I doubt that anyone would advise that gear for anything but closing a
> gap, downhill or with a strong tailwind. Just because they are
> available doesn't make them useful gears. In fact riders who think
> pedaling at speeds over 30mph when descending is useful are fooling
> themselves. You can compute the extra power required to increase
> speed from 30 to 31mph and see that it is a huge jump. I often coast
> by people who think that just because they have an 11t sprocket that
> it will help them go faster.
>
>
> Jobst Brandt
> jobst....@stanfordalumni.org
Don't forget to add in the effect of gravity to the power requirement
equation. While it may require a lot of power to increase from 30 to
31 mph on the flats, it's not that hard to do it on a downhill.
I've experienced what you describe on very steep downhills where
pedaling didn't seem to help much, but I've also been on the rivet in
the 53/12 on a moderate downhill trying to keep up with folks in their
53/11. Coasting damn sure wouldn't have made it easier! ;->
Scott
Terry Morse
> I expect that a serious rider would:
>
> a) use lower gears than 53 x 11
> b) spin higher cadences than 52 to 66 rpm
> c) go much farther than 15 miles per day
> d) pedal much faster than 20-25mph on flats
>
> But I don't know why lower gears and
> brisker pedalling work better for such
> riders. I'm so sluggish that it seems
> to me that they must be doing more
> work, raising their legs faster and so
> many more times to cover the same mile.
>
> If you have a higher-cadence explanation,
> I hope that you can dumb it down for me.
> Perhaps there's a slow-twitch diesel
> in my family tree?
"Serious riders" spin higher cadences to delay the onset of muscle
fatigue. The main cause of muscle fatigue on a longer ride (2+
hours) is the depletion of muscle glycogen, the fuel that's burned
by the leg muscles. The lower the peak muscle effort, the lower the
rate of muscle glycogen depletion. When glycogen stores are gone, a
rider can't produce nearly as much power and is forced to slow down.
Since higher cadences require lower peak muscle effort, one can ride
longer at the same power output before depleting glycogen.
A higher cadence requires a somewhat greater aerobic effort, but
this is much more preferable to muscle fatigue.
--
terry morse Palo Alto, CA http://www.terrymorse.com/bike/
Terry Morse
> I've even seen people on pseudo-MTBs _front_ shifting at lights,
> which is clearly pointless because they can't push hard during a
> front shift.
Front shifting isn't completely pointless. I'll do it sometimes when
I want a fast jump across the intersection. I get up to about 20mph
before needing to front shift, which is fast enough to not worry
about pushing hard.
Carl Fogel
[snip Fogel]
> "Serious riders" spin higher cadences to delay the onset of muscle
> fatigue. The main cause of muscle fatigue on a longer ride (2+
> hours) is the depletion of muscle glycogen, the fuel that's burned
> by the leg muscles. The lower the peak muscle effort, the lower the
> rate of muscle glycogen depletion. When glycogen stores are gone, a
> rider can't produce nearly as much power and is forced to slow down.
> Since higher cadences require lower peak muscle effort, one can ride
> longer at the same power output before depleting glycogen.
>
> A higher cadence requires a somewhat greater aerobic effort, but
> this is much more preferable to muscle fatigue.
Dear Terry,
Aha!
So it's not a matter of any mechanical
leverage, but more a matter of how soon a
particular kind of effort leaves the rider
tired.
Your explanation suggests why I've been
so puzzled. My daily ride with my adagio
cadence lasts only about 45 minutes, so
I've never found out what happens after
120 minutes.
If I'm following you, I'd last a lot
longer at a higher cadence, even though
it would take a slightly higher level
of effort.
I appreciate how nicely you explained
the situation and must try to lure you
out on other subjects.
Thanks!
Carl Fogel
jobst....@stanfordalumni.org
> Modern Top Fuel engines produce between 5,000 and 6,000
> horsepower... and there's enormous amounts of clutch slip in the
> first third of the run. If you watch video of a TF start, you can
> see the puffs of carbon fiber dust from the clutch.
> *Of course* it's for suppressing wheel slip- but clutch slip also >
allows the engine to make maximum power while not smoking the tires >
(as you said) or setting up resonance in the sidewalls (tire shake).
> Here's the output from a Top Fuel data logger:
http://www.plr.nu/images/graph.jpg
> the black line show engine rpm and the dark blue line shows speed.
> It's pretty apparent that engine RPM is nearly constant while the
> vehicle is accelerating. With a single gear ratio, the only way to
> accomplish this is through clutch slip.
That's a lot of power to be throwing off through a clutch. I'm not
privy to what they are doing with 5000hp but throwing that out as heat
somewhere is difficult. You could make a lot of steam with that.
What is apparent from the graphs is that acceleration is relatively
constant and that takes similarly increasing power. I can imagine a
torque converter involved but blowing away most of the power as slip
in a clutch exceeds my understanding of what goes on. It does require
half the energy to be converted to heat. That's 5000hp*4.4sec/2 =
2279KWH or a lot of heat, more than can be contained in a small box
without emitting flames. That's 1864KW being scrubbed off at the
start.
Jobst Brandt
jobst....@stanfordalumni.org
Terry Morse
> If I'm following you, I'd last a lot
> longer at a higher cadence, even though
> it would take a slightly higher level
> of effort.
You got the point exactly.
By the way, 20-25 mph without drafting is a pretty spirited pace on
the flats.
Tom Sherman
Jeff Wills wrote:
>
> Here's the output from a Top Fuel data logger:
> http://www.plr.nu/images/graph.jpg
> the black line show engine rpm and the dark blue line shows speed.
> It's pretty apparent that engine RPM is nearly constant while the
> vehicle is accelerating. With a single gear ratio, the only way to
> accomplish this is through clutch slip.
Not true in this case. The tires used on Top Fuel and Funny Car
dragsters are of special sidewall construction that allows the tire
diameter to increase (and frontal area to decrease) as the rotational
speed increases. Inflation pressures are also low (the tires are held to
the rims with bead-locks) which allows for a smaller diameter at low
speeds.
Changes in the diameter of bicycle tires with rotational speed are of
course so small as to be inconsequential.
Tom Sherman - 41 N, 90 W
Ryan Cousineau
jobst....@stanfordalumni.org wrote:
http://www.nhra.com/anatomy/topfuel.htm
Would you believe 1000-degree F clutches? 5 discs, 10" diameter, and
titanium bell housings.
And all that noise, noise, noise noise!
My father pointed out something interesting about traffic noise the
other day: most of it is from heavy truck transmissions.
I started paying attention during my commute, and he was right. Modern
cars are mostly eerily silent except under heavy loads. The main sound
is tire noise, though I did get passed by an accelerating Honda with a
modified intake system. The intake honk as it approached from behind was
louder than the exhaust note as it passed ahead.
The truck noise is a very distinct mechanical clatter, not apparently
from the exhaust, and (except for trucks using their retarder brakes)
the loudest sound on the road.
Power corrupts drivetrains,
Carl Fogel
Dear Ryan,
Interesting page.
"A Top Fuel chassis . . . is fabricated from 300 feet
of 4130 chromoly tubing . . . "
Hey, just like my bike!
" . . . and costs between $30,000 and $40,000"
Well, almost like my bike.
"All Top Fuel cars run a standard rear-gear ratio of 3.20-1."
Fixed-gear rules!
"Top Fuel dragsters must weigh a minimum of 2,025 pounds and
may not have a wheelbase that measures more than 300 inches
or fewer than 180 inches."
Just as fussy as the UCI.
"A complete fire-resistant driving suit, gloves, helmet,
and 360-degree neck collar must be worn."
Better not let the horrified-by-helmets crowd see this.
"The fat Goodyear slicks on back are 18 inches wide and
nearly 10 feet in circumference (118 inches)."
High-wheeler heaven! And slick tread, just like Jobst
wants. Plus there's only one brand, so the marketing
hype must be minimal.
"The rear-brake rotors measure 10 3/4 or 11 1/2 inches
in diameter and are made from either steel or carbon fiber,
activated via a hand lever in the cockpit, and utilized
only on the rear tires."
Rear-only weird-operating coaster brakes!
"Two types of front tires are used -- small airplane-style
tires, for quicker reaction times, and larger, bicycle-size
units, for better elapsed times."
When dragsters really want to move fast, they know
what kind of technology to turn to!
Carl Fogel
jobst....@stanfordalumni.org
> http://www.nhra.com/anatomy/topfuel.htm
> Would you believe 1000-degree F clutches? 5 discs, 10" diameter, and
> titanium bell housings.
Temperature is not power. We know that disc brakes on cars glow
yellow but that is no way near 5000hp. Citing temperature as a proof
of power dissipation makes me think you aren't talking about the same
problem.
> And all that noise, noise, noise noise!
> My father pointed out something interesting about traffic noise the
> other day: most of it is from heavy truck transmissions.
If you believe that you'll believe anything. The major source of
noise is tire to road displacement of air. It is a rushing noise much
like storm surf off in the distance. Who invents these tales???
Heavy truck transmissions, wow!
> I started paying attention during my commute, and he was right.
> Modern cars are mostly eerily silent except under heavy loads. The
> main sound is tire noise, though I did get passed by an accelerating
> Honda with a modified intake system. The intake honk as it
> approached from behind was louder than the exhaust note as it passed
> ahead.
I don't know on what planet you live but that is a nice story
unrelated to traffic noise. Maybe you haven't noticed sound walls
along highways. These are not in response to howling truck
transmissions. The are used even on roads that allow no trucks.
> The truck noise is a very distinct mechanical clatter, not apparently
> from the exhaust, and (except for trucks using their retarder brakes)
> the loudest sound on the road.
What noise are you talking about???
Jobst Brandt
jobst....@stanfordalumni.org
Jeff Wills
<snip>
> privy to what they are doing with 5000hp but throwing that out as heat
> somewhere is difficult. You could make a lot of steam with that.
> What is apparent from the graphs is that acceleration is relatively
> constant and that takes similarly increasing power. I can imagine a
> torque converter involved but blowing away most of the power as slip
> in a clutch exceeds my understanding of what goes on. It does require
> half the energy to be converted to heat. That's 5000hp*4.4sec/2 =
> 2279KWH or a lot of heat, more than can be contained in a small box
> without emitting flames. That's 1864KW being scrubbed off at the
> start.
>
> Jobst Brandt
> jobst....@stanfordalumni.org
Well, all of this exceeds *my* understanding by a wide margin... but
drag racers are evidently still in possession of their souls, so
*something* non-magical is happening.
If you're around, here's an event for you to attend:
http://www.infineonraceway.com/major_events/394211.html
Note that they're claiming 8,000 horsepower... so all of your
calculations may need to be revised.
Jeff
Ryan Cousineau
jobst....@stanfordalumni.org wrote:
> Ryan Cousineau writes:
>
> > http://www.nhra.com/anatomy/topfuel.htm
>
> > Would you believe 1000-degree F clutches? 5 discs, 10" diameter, and
> > titanium bell housings.
>
> Temperature is not power. We know that disc brakes on cars glow
> yellow but that is no way near 5000hp. Citing temperature as a proof
> of power dissipation makes me think you aren't talking about the same
> problem.
Well, you earlier mentioned that the numbers on the power dissipation
indicated that something must be close to melting point, if the clutches
were indeed slipping so much. I found a number (from the NHRA, who one
hopes is able to get roughly accurate data) giving an idea of what the
operating temperatures of these clutches were. Indeed, I even told you
how big they are: make some rough guesses as to material and thickness,
and I'll bet you could come up with a close-enough guess as to the
amount of power this system turns into heat that gets soaked up by the
clutch. Any remaining power presumably turns into noise or acceleration.
> > And all that noise, noise, noise noise!
>
> > My father pointed out something interesting about traffic noise the
> > other day: most of it is from heavy truck transmissions.
>
> If you believe that you'll believe anything. The major source of
> noise is tire to road displacement of air. It is a rushing noise much
> like storm surf off in the distance. Who invents these tales???
> Heavy truck transmissions, wow!
Well, I should be more precise: the loudest single source of noise was
clearly coming from each truck, and was definitely mechanical (as
opposed to from the tires) in nature. The cars were most of the total
noise, because there were more of them, but the car noise is mostly tire
noise (with a few exceptions). I shan't misrepresent my dad's claim any
further: his key point was that the transmission in a big truck is
bearing considerable loads and we know it has a fair amount of
inefficiency. I found an online claim of 95-98% efficiency for the
drivetrain. For a 500 hp engine, that means up to 25 hp lost by the
drivetrain (and that sounds suspiciously low to me). That's not all
turned into heat, and that's a lot of noise.
> > I started paying attention during my commute, and he was right.
> > Modern cars are mostly eerily silent except under heavy loads. The
> > main sound is tire noise, though I did get passed by an accelerating
> > Honda with a modified intake system. The intake honk as it
> > approached from behind was louder than the exhaust note as it passed
> > ahead.
>
> I don't know on what planet you live but that is a nice story
> unrelated to traffic noise. Maybe you haven't noticed sound walls
> along highways. These are not in response to howling truck
> transmissions. The are used even on roads that allow no trucks.
Really? This particular road was a non-freeway commuter chute with
considerable truck traffic and peak speeds of around 70 km/h (posted 50,
but you know how that goes).
All the traffic is noisy, and certainly the tire noise was quite
distinct. But the truck noise cut through.
> > The truck noise is a very distinct mechanical clatter, not apparently
> > from the exhaust, and (except for trucks using their retarder brakes)
> > the loudest sound on the road.
>
> What noise are you talking about???
Abre los ... er... what's Spanish for "ears" ... oídos?
meb
> In article <aFMEb.3769$XF6....@typhoon.sonic.net>,
> jobst....@stanfordalumni.org wrote:
> > Jeff Wills writes:
> >
> > > Modern Top Fuel engines produce between 5,000 and 6,000
> > > horsepower... and there's enormous amounts of clutch slip in the
> > > first third of the run. If you watch video of a TF start, you can
> > > see the puffs of carbon fiber dust from the clutch.
> >
> > > *Of course* it's for suppressing wheel slip- but clutch slip also >
> > allows the engine to make maximum power while not smoking the tires >
> > (as you said) or setting up resonance in the sidewalls (tire shake).
> >
> > > Here's the output from a Top Fuel data logger:
> >
> >
> > > the black line show engine rpm and the dark blue line shows speed.
> > > It's pretty apparent that engine RPM is nearly constant while the
> > > vehicle is accelerating. With a single gear ratio, the only way to
> > > accomplish this is through clutch slip.
> >
> > That's a lot of power to be throwing off through a clutch. I'm not
> > privy to what they are doing with 5000hp but throwing that out as
> > heat somewhere is difficult. You could make a lot of steam with
> > that. What is apparent from the graphs is that acceleration is
> > relatively constant and that takes similarly increasing power. I can
> > imagine a torque converter involved but blowing away most of the
> > power as slip in a clutch exceeds my understanding of what goes on.
> > It does require half the energy to be converted to heat. That's
> > 5000hp*4.4sec/2 = 2279KWH or a lot of heat, more than can be
> > contained in a small box without emitting flames. That's 1864KW
> > being scrubbed off at the start.
> opfuel.htm
> Would you believe 1000-degree F clutches? 5 discs, 10" diameter, and
> titanium bell housings.
> And all that noise, noise, noise noise!
> My father pointed out something interesting about traffic noise the
> other day: most of it is from heavy truck transmissions.
> I started paying attention during my commute, and he was right. Modern
> cars are mostly eerily silent except under heavy loads. The main sound
> is tire noise, though I did get passed by an accelerating Honda with a
> modified intake system. The intake honk as it approached from behind was
> louder than the exhaust note as it passed ahead.
> The truck noise is a very distinct mechanical clatter, not apparently
> from the exhaust, and (except for trucks using their retarder brakes)
> the loudest sound on the road.
> Power corrupts drivetrains,
> --
> Ryan Cousineau, rcou...@sfu.ca
> Fabrizio Mazzoleni Fan Club
When did drag racing switch to slip clutches?
I suspect it has been since the early 90’s.
This graph shows a relatively smooth acceleration, no 8G launch spike.
The near constant rpm speed is different from my last exposure to
dragsters.
Back in 93 when I was racing formula fords on the road course at IRP and
Don Prudhomme was testing his traction control top fueler on the drag
strip you could hear the engine rpm’s climbing.
--
Jeff Wills
> When did drag racing switch to slip clutches?
>
>
> This graph shows a relatively smooth acceleration, no 8G launch spike.
>
> The near constant rpm speed is different from my last exposure to
> dragsters.
>
> Back in 93 when I was racing formula fords on the road course at IRP and
> Don Prudhomme was testing his traction control top fueler on the drag
(This is wandering well off-topic, but what the heck- it's Christmas!)
I think multi-stage slipper clutches started appearing about 5 years
ago, after the NHRA banned electronic driver aids.
Jeff
Carl Fogel
> jobst....@stanfordalumni.org wrote in message news:<d%mEb.3490$XF6....@typhoon.sonic.net>...
[snip]
> . . . While Top Fuel cars use a single gear,
> they also have multi-stage slipper clutches. The clutch slips a set
> amount at the start, slips less at the middle of the run, and locks up
> completely at the end. This is all controlled by a
> mechanical-over-pneumatic timing system, electronic clutch management
> being prohibited by the NHRA.
>
> Multi-stage clutch tuning has risen to the same level as fuel
> injection tuning in the top levels of drag racing. IIRC, clutch
> technology is largely credited with lowering the 1/4 mile records from
> the 5.0 to the 4.4 second range.
>
> FWIW: I've been using a single-speed junker to get around town. In
> general I get through intersections quicker than most of the other
> commuters.
[snip]
> Jeff
Dear Jeff,
I do hope that your "single-speed junker,"
the one that you use "to get around town" and
with which you "get through intersections quicker
than most of the other commuters," is a bicycle
and not one of your old dragsters.
I love this even-more-interesting-than-usual
thread drift!
Thanks,
Carl Fogel
Jeff Wills
> Dear Jeff,
>
> I do hope that your "single-speed junker,"
> the one that you use "to get around town" and
> with which you "get through intersections quicker
> than most of the other commuters," is a bicycle
> and not one of your old dragsters.
>
> I love this even-more-interesting-than-usual
> thread drift!
>
> Thanks,
>
> Carl Fogel
Yup, it's a rescued Raliegh- useful for the stoplight drags because
it's got a relatively low gear (44/17) for a single speed and
light-but-strong wheels (36 spokes, MA-40 and Sun M14A rims). I built
it for the last three miles of my commute, after parking my Toyota
where I don't have to pay extortionate parking charges. Other days I
ride all the way from home- but I usually only use 5 of the available
24 gears on that bike.
And to drift things back towards on-topic, sort of: I help put on the
Human Power Challenge in Portland every year over Memorial Day
weekend. We got drag races:
http://www.ohpv.org/pir2003/drags/index.htm .
(Sorry to burst your bubble, Jobst- but I'm an incorrigible weird bike
nut.)
Jeff
Tom Sherman
Jeff Wills wrote:
>
> Yup, it's a rescued Raliegh- useful for the stoplight drags because
> it's got a relatively low gear (44/17) for a single speed and
> light-but-strong wheels (36 spokes, MA-40 and Sun M14A rims). I built
> it for the last three miles of my commute, after parking my Toyota
> where I don't have to pay extortionate parking charges. Other days I
> ride all the way from home- but I usually only use 5 of the available
But how many effective gear ratios does the bike have once duplicates
and near duplicates are eliminated? In a normal 3x8 setup, I would
expect about 10 or so near duplicate ratios. I have a stock bike with a
triple crank and 8-speed cluster that has 10 ratios that are near
duplicates (difference of 2 gear inches or less).
Carl Fogel
Dear Jeff,
Good Lord!
Those bicycle drag-racers are accelerating
so fast that their upper bodies are being
forced visibly backward!
Carl Fogel