Why is the hour record done in a fixed gear?
Robert Chung
(one-hour) power is maximized at one fixed cadence? If not, is it
because people think that the gain in drivetrain efficiency
outweighs any loss in power from riding at a fixed cadence?
Part Duh! of my question, perhaps only peripherally related: why
are there so many rear cogs? Gasoline engine cars often have as
few as three forward speeds, while diesel trucks have many, many
more. I was told that was because diesels have a narrow torque
band (with respect to rpm). Are humans like diesels, and do we
prefer to be in a narrow cadence band?
--Robert Chung
John Forrest Tomlinson
news:3C04BE08...@aol.com...
> Is it because it's done on a track? Is it because sustainable
> (one-hour) power is maximized at one fixed cadence? If not, is it
> because people think that the gain in drivetrain efficiency
> outweighs any loss in power from riding at a fixed cadence?
What loss of power? Apart from the start the rider is going, ideally,
at the same speed, so using the same cadence makes sense.
JT
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Visit http://www.jt10000.com
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KBFREY
or as my grandma said 'a stitch in time saves nine'. fixed is faster, get the
fever.
Uncle Chainwhip
Robert Chung
>
> "Robert Chung" <REC...@aol.com> wrote in message
> news:3C04BE08...@aol.com...
> > Is it because it's done on a track? Is it because sustainable
> > (one-hour) power is maximized at one fixed cadence? If not, is it
> > because people think that the gain in drivetrain efficiency
> > outweighs any loss in power from riding at a fixed cadence?
>
> What loss of power? Apart from the start the rider is going, ideally,
> at the same speed, so using the same cadence makes sense.
I was unclear. Going at the same cadence makes sense if that's
the cadence (and gearing) that maximizes power over the hour. So
I was predicating the question on the "if not" part. So perhaps
to make things clearer, I might have written "outweighs any loss
of power from riding at the *wrong* fixed cadence."
Knowing you'd have to go 49+ km in an hour, you also know how
much power you have to average during that hour. So you pick a
gearing and cadence that will let you go 49 km plus some change
in that time. But why *that* gearing and cadence? Presumably
because you know that's the gearing and cadence that maximizes
your power for an hour. But if you're off in your calculation,
why wouldn't you switch gears and cadence? You could do that if
you were riding a multispeed bike.
Robert Chung
What proportion of time is spent at TDC and BDC on a fixed gear
versus a freewheel? And how does this affect speed?
Andrew Coggan
Total nonsense.
Andy Coggan.
Robert Chung
Andy, you're so much more to the point than I.
Anyway, when Boardman rode his hour, he must have known that he
had to average 440+ watts to do it. I presume he made a choice of
gearing and cadence that would get him those watts. Would he have
been able to produce 440+ watts for 3600 seconds at other
gearing-cadence combos? And, a side issue: is the amount of power
needed to go around a track the same on the turns as on the
flats?
--Robert
Ewoud Dronkert
> But if you're off in your calculation, why wouldn't you
> switch gears and cadence? You could do that if
> you were riding a multispeed bike.
Ah, but my guess is they test these things beforehand....
John Forrest Tomlinson
> the cadence (and gearing) that maximizes power over the hour. So
> I was predicating the question on the "if not" part. So perhaps
> to make things clearer, I might have written "outweighs any loss
> of power from riding at the *wrong* fixed cadence."
I'd imagine that most people going for the hour record are careful
enough to calculate the cadence and gear needed very, very closely.
Closer than the difference between rear cogs one tooth apart.
Robert Chung
> I'd imagine that most people going for the hour record are careful
> enough to calculate the cadence and gear needed very, very closely.
> Closer than the difference between rear cogs one tooth apart.
I would have thought so, too. But
<http://ida1.physik.uni-siegen.de/menn/hourrec.htm> shows the
gearing-cadence choices for the hour record. When Moser broke
Merck's record, he did so with a 56x15. Four days later, he went
back with a 57x15 and broke it again. When Boardman broke Obree's
week-old record in 1993, he did so on a 53x13 (at 102rpm). When
he recaptured the record in 1996, he did so on a 56x13 (at
105rpm).
I can't find what gear and cadence he used last year when he set
the new UCI hour record.
I going to presume (baldly) that Boardman was producing close to
the same amount of power in his three attempts, and that the main
difference was aero drag. If so, doesn't this mean that he could
produce the same (or ballpark same) power at different
gear-cadence combos?
So, this was sorta how I backed into the second part of my
question. If we (not just Boardman) can produce sustainable
maximal power at different gear-cadence combos, why do we have so
many cogs?
Ewoud Dronkert
> I going to presume (baldly)
Try http://pages.prodigy.com/HAMMO/
> why do we have so many cogs?
3 is enough on the flat, 7 in the mountains. But different combos for
different riders. Also, Shimano et al want to keep "innovating" to promote
sales.
Gary King
> And, a side issue: is the amount of power
> needed to go around a track the same on the turns as on the
> flats?
Nope, it appears you need to crank more on the curves. The explanation I
get from the guys at the velodrome (where I occasionally make an
appearance when I'm not lazy) is that the centriputal force acting on
the bike on the banked turn compresses the tyres more and increases
their rolling resistance.
Well that's their theory and I'll stick with that till someone comes up
with a better one..
Gary King
Carl Sundquist
than the straights to maintain the same speed. The reason being that your
center of mass is traveling on a curve roughly 1 meter or so in radius
smaller than the surface where the wheels are touching. Since the inertia of
your CoM is going to maintain the same speed, your wheels must travel faster
to keep up with your CoM. This effect isn't really noticeable on 333 and
larger tracks. On smaller tracks, the percentage difference in radius makes
the effect more pronounced. In other words, on a 250 track you would tend to
float (less pressure on the pedals) in the bends to hold the same speed as
on the straights.
At the tire pressures used in an hour record attempt (11-12 bar), your tires
are not likely to compress much more on the bends than on the straights. As
far as I know, no one has ever mentioned sprinters bogging down in the bends
due to increased rolling resistance and they are riding about 10 kph faster
than an hour record speed.
"Gary King" <oce...@iinet.net.au> wrote in message
news:1f3lusq.11useziqdrl0pN%oce...@iinet.net.au...
Robert Chung
> Actually, it is generally recognized that you need less wattage in the bends
> than the straights to maintain the same speed.
> larger tracks.
Have more records been set on shorter tracks or on longer tracks?
Daniel Connelly
>
> Actually, it is generally recognized that you need less wattage in the bends
> than the straights to maintain the same speed. The reason being that your
> center of mass is traveling on a curve roughly 1 meter or so in radius
> smaller than the surface where the wheels are touching. Since the inertia of
> your CoM is going to maintain the same speed, your wheels must travel faster
> to keep up with your CoM.
Well, it's not really your COM, but CO-(a more complicated function of
local wind resistance).
For example -- if I were to mount a massless parachute,
and did so at the position of the hubs as opposed to from the seat,
the effect on drag in the corners would be greater, even if my COM position
is unaffected.
But the point is still valid : the center of wind resistance takes
a shortcut through the corner.
Consider : a 250 meter track with the bike is leaning 45 degrees
in the corners, and the center of wind resistance is 1 meter "above"
the contact point (bike frame of reference),
savings per lap is (2 pi)(1 meter)(1/sqrt(2)) = 4.44 meters
per lap. This is 1.8% or 900 meters per 50km traveled.
Highly nontrivial.
Dan
jobst....@stanfordalumni.org
> Is it because it's done on a track? Is it because sustainable
> (one-hour) power is maximized at one fixed cadence? If not, is it
> because people think that the gain in drivetrain efficiency
> outweighs any loss in power from riding at a fixed cadence?
I'm not sure what part of the effort you mean, however, starting in
the same gear that is used for the constant speed part has been
questioned, especially for the kilometer and 440m pursuit. All sorts
of gears have been tried to optimize acceleration at the start and
none produced an improvement. I think that question has been
correctly laid to rest.
> Part Duh! of my question, perhaps only peripherally related: why are
> there so many rear cogs? Gasoline engine cars often have as few as
> three forward speeds, while diesel trucks have many, many more. I
> was told that was because diesels have a narrow torque band (with
> respect to rpm). Are humans like diesels, and do we prefer to be in
> a narrow cadence band?
That is a dangerous subject. The spin advocates often attack people
who do not keep (or at least claim to) never ride below 90rpm,
ignoring what one can see of action in classic professional races.
Every rider has a preferred way to ride in the flat and hills.
No, we don't need all those gears. Probably half as many would do
fine. With shifting on the bars and 30 gears from which to choose, I
see riders on gently rolling terrain constantly shifting to stay in
their diesel truck range. It's a tic, not a necessary function.
Jobst Brandt <jobst....@stanfordalumni.org>
Steven L. Sheffield
wrote:
> Is it because it's done on a track? Is it because sustainable
> (one-hour) power is maximized at one fixed cadence? If not, is it
> because people think that the gain in drivetrain efficiency
> outweighs any loss in power from riding at a fixed cadence?
Who cares about any of those reasons?
The main reason is because the UCI says so.
http://www.uci.ch/english/about/rules/ch03_track.pdf, starting with
section 3.5.001.
Rules specifically relating to the Hour Record are:
Hour Record
The Hour Record is the greatest distance achieved in one hour on a
traditional bicycle, as defined in articles 1.3.006 to 1.3.010 and
1.3.019 of the rules, and as further defined in the following
specifications:
? Triangular frame composed of straight, circular section tubes with a
minimum diameter of 2.5 cm.
? Traditional style handlebars with an overall width of 50 cm maximum and
34 cm minimum.
? Two wheels of equal diameter, measuring 65 to 70 cm, including tyres
? Tyre section of a minimum of 16 mm and a maximum of 25 mm.
? Spoked wheels with a minimum of 16 and a maximum of 32 spokes; the
spokes may be round, flat or oval provided that none of their
cross-sections exceeds 2 mm. (See diagram 1 below)
? Shallow, unelongated, non-profiled rims; shallow rims are understood
to be rims whose cross-section fits inside a 2.2 cm square.
? Other measurements in accordance with those defined in articles
1.3.012 to 1.3.017 (see figure "Measurements") and 1.3.022, 1.3.024 and
1.3.025.
(1) The spokes may be round, flat or oval as long as the width of a
cross-section at any point is no broader than 2 mm in any direction.
(2) Shallow rims are understood to be rims whose cross-section fits
inside a 2.2 cm square.
? Riders must wear a helmet certified according to international safety
standards, intended solely for the purposes of protecting the head,
without a visor, and without any devices or shapes added to or moulded
into the helmet with the intention of or having the effect of reducing
air resistance.
Articles 1.3.026 and 1.3.033 will be strictly applied.
(Article came into force on 1st October 2000).
Best Hour Performance
The Best Hour Performance is the greatest distance achieved in one hour
on a bicycle conforming to articles 1.3.006 to 1.3.010. The bicycle
shall be submitted to the Equipment Commission for approval 15 days
before the date of the attempt. The rider starts from the pursuit line
as defined in article 3.6.083.
The timekeeper shall, by ringing a bell, indicate the last lap (or the
lap during which the hour expires) when the time remaining to ride is
less than the average time realised over one lap of the track. The
attempt shall terminate when the rider crosses the pursuit line from
which he started. The end shall be indicated by a double pistol shot.
The distance covered in the hour shall be calculated as follows:
D = (L Pi x TC) + Di C
Di C = L Pi x TRC
TTC
Where:
D = distance covered in the hour
L Pi = length of track
TC = number of complete laps before the last lap
Di C = additional distance
TTC = time of the last complete lap
TRC = time remaining to ride at the beginning of the last lap
The distance covered shall be rounded down to the nearest metre. Neither
the Hour Record nor the Best Hour Performance may be beaten by less than
one metre.
(Amendment came into force on 1st October 2000).
If, between the expiry of the hour and the end of the last lap, an
incident occurs to prevent completion of the lap, the additional
distance shall be calculated on the basis of the time of the lap before
last.
--
--
Steven L. Sheffield
stevens at veloworks dot com
veloworks at mac dot com
aitch tee tea pea colon forward slash four-word slash double-you double-yew double-ewe dot veloworks dot com
Robert Chung
> The main reason is because the UCI says so.
>
> http://www.uci.ch/english/about/rules/ch03_track.pdf, starting with
> section 3.5.001.
Actually, I read all of that before I posted. At least in that
stuff, I couldn't find anything that said you couldn't have
gears. So I presumed that the rider doesn't have gears for a
mechanical/physiological reason, and that he picks the gear (and
thus, cadence) that he thinks will get him the farthest distance
in one hour.
So what's the basis for thinking that a particular gear will get
him the farthest?
--Robert
Dan Connelly
> The main reason is because the UCI says so.
>
>
Interesting, but :
* I saw no mention of a fixed drivetrain in those rules.
* The question pertains to historical events, most of which
occurred prior to the drafting of these rules.
* These rules apply to only one of the two recognized hour records,
with the other freed from the new bicycle restrictions.
Dan Connelly
The reason is :
* the best effort over a given duration tends to be the highest sustainable
steady effort
* the drivetrain efficiency of a fixed drivetrain is superior to a geared
drivetrain
* the "start-up" cost with having a nonoptimal gear for the acceleration
phase is small in comparison to the savings in drivetrain efficiency.
* the optimal cadence in the corners isn't substantially different from that
on the straights due to the competing factors of increased stress from
the cornering, and the fact your wheels are taking a longer path than
the center of wind resistance.
Dan
Robert Chung
> The reason is :
>
> * the best effort over a given duration tends to be the highest sustainable
> steady effort
> * the drivetrain efficiency of a fixed drivetrain is superior to a geared
> drivetrain
> * the "start-up" cost with having a nonoptimal gear for the acceleration
> phase is small in comparison to the savings in drivetrain efficiency.
> * the optimal cadence in the corners isn't substantially different from that
> on the straights due to the competing factors of increased stress from
> the cornering, and the fact your wheels are taking a longer path than
> the center of wind resistance.
Okay, I guess can buy all of that (especially since no one else
has offerred anything else). So, how do you choose that single
gear that you have, i.e., how do you figure out what the highest
sustainable effort is? This gets back to the second part of my
question, which is: is the max sustainable power for these guys
limited to a narrow cadence? Can you produce max sustainable
power at multiple gears (and cadences)?
--Robert
Steven L. Sheffield
Dan Connelly <djco...@ieee.org> wrote:
Of course, what I pasted makes reference to section 1.3.025 which states:
1.3.025
Freewheels, multiple gears and brakes are not permitted for use on the
track during competition or training.
C'mon Dan ... you're usually the one that has all this research shit
down!
Steven L. Sheffield
wrote:
> "Steven L. Sheffield" wrote:
> > The main reason is because the UCI says so.
> >
> > http://www.uci.ch/english/about/rules/ch03_track.pdf, starting with
> > section 3.5.001.
>
> Actually, I read all of that before I posted.
Really ... did you go check the references to other sections as well?
Specifically section 1.3.025, which states:
1.3.025
Freewheels, multiple gears and brakes are not permitted for use on the
track during competition or training.
> At least in that
> stuff, I couldn't find anything that said you couldn't have
> gears. So I presumed that the rider doesn't have gears for a
> mechanical/physiological reason, and that he picks the gear (and
> thus, cadence) that he thinks will get him the farthest distance
> in one hour.
>
> So what's the basis for thinking that a particular gear will get
> him the farthest?
>
> --Robert
--
Ilan Vardi
> gearing-cadence choices for the hour record. When Moser broke
> Merck's record, he did so with a 56x15. Four days later, he went
> back with a 57x15 and broke it again. When Boardman broke Obree's
> week-old record in 1993, he did so on a 53x13 (at 102rpm). When
> he recaptured the record in 1996, he did so on a 56x13 (at
> 105rpm).
I believe that Moser used a rear wheel which was bigger than the
usual 700c, so the above gearing figures cannot be compared
directly with the gearing used by all other riders who did use
a 700c wheel. By the way, low profile track tires produce slightly shorter
rollouts than what is computed by the usual formulas, but I would
suppose that all these riders used similar tire profiles.
-ilan
Robert Chung
>
> In article <3C053DF1...@aol.com>, Robert Chung <REC...@aol.com>
> wrote:
>
> > "Steven L. Sheffield" wrote:
> > > The main reason is because the UCI says so.
> > >
> > > http://www.uci.ch/english/about/rules/ch03_track.pdf, starting with
> > > section 3.5.001.
> >
> > Actually, I read all of that before I posted.
>
> Really ... did you go check the references to other sections as well?
> Specifically section 1.3.025, which states:
>
> 1.3.025
>
> Freewheels, multiple gears and brakes are not permitted for use on the
> track during competition or training.
Nope. Thanks (but then, you could've just posted 1.3.025 rather
than 3.5.001).
--Robert
Ilan Vardi
> Actually, it is generally recognized that you need less wattage in the bends
> than the straights to maintain the same speed. The reason being that your
> center of mass is traveling on a curve roughly 1 meter or so in radius
> smaller than the surface where the wheels are touching. Since the inertia of
> your CoM is going to maintain the same speed, your wheels must travel faster
> to keep up with your CoM. This effect isn't really noticeable on 333 and
> larger tracks. On smaller tracks, the percentage difference in radius makes
> the effect more pronounced. In other words, on a 250 track you would tend to
> float (less pressure on the pedals) in the bends to hold the same speed as
> on the straights.
Velodromes are built so that there is a hill going into the turn and
dowhill out of the turn. This is obviously true up on the banking
where
you almost feel like you're riding up the Alps when you're tired, but
might still hold on the pole line where the hour record is ridden.
This would imply a loss of energy, since you
have to go up and down.
By the way, I hope I got that right, and it's not the other way around
(it's been way too long since I rode the track).
As for the fixed gear, I maintain (personal opinion) that
a fixed gear will smooth out your stroke and hide imperfections
due to the flywheel effect, so there's no technical reason that a
freewheel setup would be superior. However, Indurain might have been
an exception, since he had the habit of starting out his time trials
out of the saddle,
then coasting in order to sit back down, not a good idea on a fixed
fear. His successful hour record
attempt was apparently his first time on a track (i.e., including
his one or two training sessions).
There were numerous attempts to have gearing on kilometer bikes,
including
some 2 gear systems, but these were either unreliable or made illegal.
Anyway, the following may be true: The start is made using the short
term
physical energy system (about 10 seconds) so doing an extremely
violent
strength effort (i.e., pushing a big gear at the start) to get up to
speed will not penalize
you if you very quickly get into an aerobic threshold rythm. Once
again,
my own personal opinion. I invite criticism.
-ilan
Ewoud Dronkert
> is the max sustainable power for these guys
> limited to a narrow cadence?
I always thought (was told/read once) lower cadences are more efficient
(biomechanical optimum ridiculously low, like 50 or so), but you need more
strength which you can't maintain for one hour. That must lead to one
specific, optimum cadence for maximum hour-distance.
John Forrest Tomlinson
news:9u3m37$2ej$1...@news1.xs4all.nl...
> "Robert Chung" <REC...@aol.com> wrote:
> > is the max sustainable power for these guys
> > limited to a narrow cadence?
>
> I always thought (was told/read once) lower cadences are more
efficient
> (biomechanical optimum ridiculously low, like 50 or so),
Efficiency on a bike is a means using the minimum amount of effort
(variously defined) to go a given speed. But that's not what racing or
setting a world record is about -- it's about making as much of you
effort usable so you can go as fast/far as possible.
jobst....@stanfordalumni.org
> So, how do you choose that single gear that you have, i.e., how do
> you figure out what the highest sustainable effort is? This gets
> back to the second part of my question, which is: is the max
> sustainable power for these guys limited to a narrow cadence? Can
> you produce max sustainable power at multiple gears (and cadences)?
By the time you are ready to attack the hour record, you will have
discovered the optimal TT gear for flat road distances in the range
expected. Even club 25mi TT events, most riders know what gear to
use, assuming no wind. The hour record is invalid with any wind over
some minimal amount anyway.
Jobst Brandt <jobst....@stanfordalumni.org>
Henry Chang
Perhaps.
But Moser didn't think so. How about his oversized wheel with 1 wheel
rev. corresponding to 1 pedal rev with the weights 90 degrees offset
from the cranks?
Henry
Bob Schwartz
This being rbr you can bet that someone has been there and done
that with respect to just about any discussion. I'll see if I
can summarize this one.
I've pointed out that max power for hour record holders comes
at a cadence around 105 rpm.
http://www.angelfire.com/realm/cvccbikers/misc/hour-record.html
Usually Andrew Coggan jumps in about this point and notes that
things are different for champion cyclists capable of really
high power outputs compared to ordinary guys with more limited
abilities, and that for people with lower max power, optimal
cadence over an hour is lower.
Now be has a boatload of publications and I don't but I'm still
a skeptic. The reason I'm a skeptic is that I think there are a
lot of guys out there with the power output of a guy like Oscar
Egg, for whom power over an hour maxed at 103 rpm. So, while I
believe him when he says that the optimal cadence rises with
max power, I think there is an asymptote to the function and
that it's relatively low.
Your turn Andrew...
Bob Schwartz
cv...@execpc.com
Andrew Coggan
BTW, is the first I've heard of this...the primary explanation I've seen
given for the use of the very large wheel was that it was for the
aerodynamic benefit: the greater height and length/depth helped to reattach
the airflow and reduce drag, much like the "butt fairings" used in the
1930's). The only way it could possibly have an effect is if one were such a
"lazy pedaler" that the top run of the chain would go slack, and the bottom
would become fully tensioned, and it is doubtful that Moser (or anyone else)
is that "sloppy".
Try riding a fixed gear bike with a little extra slack in the chain, and
you'll see (or feel) exactly what I mean...it makes absolutely no difference
unless you deliberately slow your pedaling at top/bottom dead center.
Andy Coggan
"Henry Chang" <henrichang....@home.com> wrote in message
news:3c056a54.244622142@news...
Andrew Coggan
hour record material) would be able to quickly determine the "perfect" rear
cog, and would probably be w/in 1-2 teeth as to the "perfect" chain ring,
after just a little experimentation. So, while it *might* be helpful to
switch between, say, a 54 and a 55 in the middle of an attempt, the
difference between them is so small, and the human power/cadence curve so
"flat" at its optimum, that it would likely have very little effect on the
distance covered in one hour. From looking at some of the attempts (even
some successful ones), it seems that there would be more to gained by
optimizing pacing strategy...
Andy Coggan
"John Forrest Tomlinson" <20...@jt10000removethesewords.com> wrote in message
news:Ms5N7.157366$dk.11...@bin1.nnrp.aus1.giganews.com...
Andrew Coggan
> This gets back to the second part of my
> question, which is: is the max sustainable power for these guys
> limited to a narrow cadence? Can you produce max sustainable
> power at multiple gears (and cadences)?
No, and yes.
There is less information on submaximal vs. maximal power, since it is more
difficult (fatiguing) to test the former. However, since from a
cadence/speed of muscle contraction perspective there isn't much difference
as to the underlying mechanisms, results obtained during the latter can be
logically extended to the former. What testing of maximal power shows is
that the relationship between power and cadence can be well described by an
inverted hyperbola, with a relatively "broad" quasi-plateau region. Over a
span of +/- 5 rpm from optimum, power will only vary by a couple of percent.
Since there is at least as much difference in performance on a day to day
basis, there is little logic in putting too much effort into trying to pick
the "perfect" gear, since there's no way of knowing that it will be truly
perfect on race day. IOW, if the difference between using, say, a 55 vs a 54
makes the difference in taking the record, setting a new standard is going
to be as much a function of luck as planning...
Andy Coggan
Andrew Coggan
record holders? I'd have to dig up some articles to check, but I'll bet his
estimated power was at least 375 W...perhaps as much as 400 W. (Keep in mind
that VO2max values of greater than 70 mL/kg/min have been recorded for
champion runners since the 1930's...IOW, although athletes are clearly
getting better over time, the rate of improvement isn't nearly as great as
you imply, and certainly isn't as great as the progress of the hour record
might suggest.)
I stand by my earlier statements: just because hour record holders producing
375-442 W (excluding Indurain, who was estimated to produce ~515 W) pedal at
100 rpm (Obree being a notable exception) doesn't mean that mere mortals
producing only about two-thirds that power must pedal that fast.
Andy Coggan
"Bob Schwartz" <cv...@shell.core.com> wrote in message
news:3c0573d5$0$30969$272e...@news.execpc.com...
Carl Sundquist
If there were two weights on opposite sides of each other, they would cancel
out any TDC or BDC effect of the wheel and it would be the inertia of the
weights which would help to overcome any dead spots in the pedal stroke,
regardless of their position relative to the cranks.
Bob Schwartz
> Why do think Oscar Egg's power was so much lower than that of more recent
> record holders? I'd have to dig up some articles to check, but I'll bet his
> estimated power was at least 375 W...perhaps as much as 400 W. (Keep in mind
> that VO2max values of greater than 70 mL/kg/min have been recorded for
> champion runners since the 1930's...IOW, although athletes are clearly
> getting better over time, the rate of improvement isn't nearly as great as
> you imply, and certainly isn't as great as the progress of the hour record
> might suggest.)
> I stand by my earlier statements: just because hour record holders producing
> 375-442 W (excluding Indurain, who was estimated to produce ~515 W) pedal at
> 100 rpm (Obree being a notable exception) doesn't mean that mere mortals
> producing only about two-thirds that power must pedal that fast.
Egg broke the record twice. I've calculated a 40K
time for each:
Year Distance 40K
1912 42.122 56:58
1914 44.427 54:01
In 1982 I stripped down my road bike and rode the
Wisconsin State TT with a fixed gear and a front
brake. Square rims, 36 spokes. It probably wasn't
that different from the bike Egg rode. I knew
nothing about training, just went out and rode. No
speed work, nothing specific to any aspect of the
sport. Just a punk kid who liked to ride his bike.
I rode a 52 X 14 because I knew that's what Merckx
rode in Mexico City.
I won in 56:50. It was a good ride, and while I was
winning my share of races it wasn't like I was
burning up the road, there were plenty of people
going as well or better. The road surface was OK
but not great, certainly not as good as what you'd
see at a velodrome used for a record attempt. And
it was in a straight line with a turnaround, so no
gains from a shorter line in the banking. The
course had been surveyed for nationals so I know
it was accurate. Actually I should probably knock
a few seconds off that time because that was one
of the last years it was run at 25 miles which is
a tad longer than 40K.
I'm pretty sure I came close to that in a later
year on a course with a much worse road surface and
on a bike with gears. I wasn't killing people then
either. In fact, I didn't even win the race. A guy
that showed up with a Hed prototype, supposedly one
of the first that Steve made in his basement, took
that one.
I bought a funny bike with a disc wheel in 1986 so
that was the end of the comparisions with Egg. I
never went as fast as the 1914 time, but I was at
least within spitting distance. I think that if I
was in the ballpark back then, then so were a lot
of people. And a lot of people are now, especially
when you consider how much higher the level of
sophistication is about riding and training is from
what I had then.
Hell, that 56:50 works out to 89 rpm. I was such a
dope I picked the wrong gear!!
Bob Schwartz
cv...@execpc.com
thomas arnone
Robert Chung
> What testing of maximal power shows is
> that the relationship between power and cadence can be well described by an
> inverted hyperbola, with a relatively "broad" quasi-plateau region. Over a
> span of +/- 5 rpm from optimum, power will only vary by a couple of percent.
Bingo. Thanks. This is exactly what I was wondering.
Um, should I then ask why we have so many rear cogs, or am I
pushing my luck?
--Robert
Henry Chang
beats me, I didn't design it.
Henry
Andrew Coggan
In the context of the present discussion, I thought it might be interesting
if you shared your thought processes in arriving at the gear you used to
clock that 50:18 at master nationals. In particular, do you think you could
have cracked the 50 min barrier like you wanted to if you'd used a different
gear? <grin>
Andy Coggan
"Carl Sundquist" wrote:
(Something not directly relevant to my question above)
Andrew Coggan
Because speed varies much, much more when riding on varied terrain than when
riding on a velodrome...simple as that.
Andy Coggan
Andrew Coggan
56:50...this was a non-aero, drop bar equipped (geared) road bike typical of
the time. Power meters weren't available back then, but I estimate that my
sustained power was around 350 W. Egg went just as fast in 1912, and much
faster in 1914, on equipment/under conditions that was (probably)
significantly more primitive....his power was therefore likely even higher
(I will look up some more accurate estimates later today to satisfy you).
Andy Coggan
"Bob Schwartz" <cv...@shell.core.com> wrote in message
news:3c05ccee$0$43573$272e...@news.execpc.com...
Robert Chung
> > > What testing of maximal power shows is
> > > that the relationship between power and cadence can be well described
> > > by an inverted hyperbola, with a relatively "broad" quasi-plateau
> > > region. Over a span of +/- 5 rpm from optimum, power will only vary
> > > by a couple of percent.
> >
> > Bingo. Thanks. This is exactly what I was wondering.
> >
> > Um, should I then ask why we have so many rear cogs, or am I
> > pushing my luck?
>
> Because speed varies much, much more when riding on varied terrain than when
> riding on a velodrome...simple as that.
Darn. You know, I'm not trying to be dense (many people say that
is something I don't really have to try to achieve) but I would
have thought you'd say that a span of +/- 5 rpm at 100 rpm (for
example) is about 5%, which is around the same magnitude as a
one-tooth difference in cogs. So one really would need all these
damn cogs in order to stay in the right power-producing region.
--Robert Chung
Gary King
train. Probabely doesn't apply to a solo rider . In a train (or
paceline) one must definately power through the banking to prevent a gap
appearing. This what is taught to beginners at our velodrome. Maybe
because part of the drafting benefit is lost on the curve.
GK
Carl Sundquist <car...@cox-internet.com> wrote:
> Actually, it is generally recognized that you need less wattage in the bends
> than the straights to maintain the same speed. The reason being that your
> center of mass is traveling on a curve roughly 1 meter or so in radius
> smaller than the surface where the wheels are touching. Since the inertia of
> your CoM is going to maintain the same speed, your wheels must travel faster
> to keep up with your CoM. This effect isn't really noticeable on 333 and
> larger tracks. On smaller tracks, the percentage difference in radius makes
> the effect more pronounced. In other words, on a 250 track you would tend to
> float (less pressure on the pedals) in the bends to hold the same speed as
> on the straights.
>
> At the tire pressures used in an hour record attempt (11-12 bar), your tires
> are not likely to compress much more on the bends than on the straights.
> As
> far as I know, no one has ever mentioned sprinters bogging down in the bends
> due to increased rolling resistance and they are riding about 10 kph faster
> than an hour record speed.
Carl Sundquist
(not floating through the bends) accelerates slightly through the bends, and
being the lead rider, begins that acceleration before each of the following
riders. The other riders must pedal harder to hold the same gap between the
wheels.
"Gary King" <oce...@iinet.net.au> wrote in message
news:1f3nkph.1mgiz7j1qfv4taN%oce...@iinet.net.au...
Bob Schwartz
> So what is your point? First time I went under the hour I also clocked a
> 56:50...this was a non-aero, drop bar equipped (geared) road bike typical of
> the time. Power meters weren't available back then, but I estimate that my
> sustained power was around 350 W. Egg went just as fast in 1912, and much
> faster in 1914, on equipment/under conditions that was (probably)
> significantly more primitive....his power was therefore likely even higher
> (I will look up some more accurate estimates later today to satisfy you).
My point is that people with Egg-like power output were not rare
in the early 80s and are certainly not rare now.
I'm curious how you think Egg's equipment was significantly more
primitive. I'm not an expert in the history of concrete but my
assumption is that there were many velodromes available back
then with surfaces significantly better than what I was riding
on in 1982. I was riding on thinner tires with higher pressure,
but I was cheap and I wasn't going to pump them up much higher
than 100 psi. He was able to pick the venue and date. How were
things harder for him?
Bob Schwartz
cv...@execpc.com
Scott Hendricks
Put your coach's hat on for a minute, and consider:
You've got a cyclist, maybe fairly well trained, maybe not, who you've
tested
and found that he's producing that 2/3's power you mention, at about 75 rpm.
You want to help him train for an hour record attempt.
Do you:
1) help him maximize his power at his current optimum cadence, or
2) train him to increase his optimum cadence to around 100 rpm, and then
maximize the power at the new cadence?
Scott
>===== Original Message From "Andrew Coggan" <andya...@erols.com> =====
>Why do think Oscar Egg's power was so much lower than that of more recent
>record holders? I'd have to dig up some articles to check, but I'll bet his
>estimated power was at least 375 W...perhaps as much as 400 W. (Keep in mind
>that VO2max values of greater than 70 mL/kg/min have been recorded for
>champion runners since the 1930's...IOW, although athletes are clearly
>getting better over time, the rate of improvement isn't nearly as great as
>you imply, and certainly isn't as great as the progress of the hour record
>might suggest.)
>
>I stand by my earlier statements: just because hour record holders producing
>375-442 W (excluding Indurain, who was estimated to produce ~515 W) pedal at
>100 rpm (Obree being a notable exception) doesn't mean that mere mortals
>producing only about two-thirds that power must pedal that fast.
>
>Andy Coggan
Daniel Connelly
> You've got a cyclist, maybe fairly well trained, maybe not, who you've
> tested
> and found that he's producing that 2/3's power you mention, at about 75 rpm.
>
> You want to help him train for an hour record attempt.
>
> Do you:
> 1) help him maximize his power at his current optimum cadence, or
> 2) train him to increase his optimum cadence to around 100 rpm, and then
> maximize the power at the new cadence?
>
This is a good question. If one neglects technique training from global
performance optimization, one can conclude
many riders should be riding with a completely upright position and the
chain on the small-small cross gear. That seems to be where they
are currently most efficient....
But I don't dispute Andrew's claim, simply because I lack any compelling
data or arguments to do so.
Dan
Scott Anderson
> because you know that's the gearing and cadence that maximizes
> your power for an hour. But if you're off in your calculation,
> why wouldn't you switch gears and cadence? You could do that if
> you were riding a multispeed bike.
Testing, training, more testing, more training. Pursuiters finesse it down
to half a gear-inch depending on how the legs feel, wind conditions (not a
factor indoors) and track type. The hour is just a looooong pursuit.
I guess you could argue that the optimal gear/cadence changes over time as
muscles fatigue but even if that were true I don't know if the gains would
outweigh the greater effeciency of the fixed gear drivetrain.
Carl Sundquist
> >> But Moser didn't think so. How about his oversized wheel with 1 wheel
> >> rev. corresponding to 1 pedal rev with the weights 90 degrees offset
> >> from the cranks?
> >>
> >What purpose would having the weights offset 90 degrees to the cranks
serve?
> >If there were two weights on opposite sides of each other, they would
cancel
> >out any TDC or BDC effect of the wheel and it would be the inertia of the
> >weights which would help to overcome any dead spots in the pedal stroke,
> >regardless of their position relative to the cranks.
>
>
>
> beats me, I didn't design it.
>
Carl
Carl Sundquist
"Ilan Vardi" <ila...@yahoo.com> wrote in message
news:b26c09dc.01112...@posting.google.com...
> "Carl Sundquist" <car...@cox-internet.com> wrote in message
news:<u0a1j52...@corp.supernews.com>...
>
> As for the fixed gear, I maintain (personal opinion) that
> a fixed gear will smooth out your stroke and hide imperfections
> due to the flywheel effect, so there's no technical reason that a
> freewheel setup would be superior.
A fixed gear doesn't necessarily smooth out your stroke any more than a
freewheel setup. Having the cranks kick your feet forward won't help smooth
out your stroke. A smooth stroke is most easily achieved by both steady rpms
(regardless of the rate) and consciously pedaling through the crank circle
and by undergearing, using LOTS of chamois cream and pedaling your ass off.
Unless you have a tendency to pause every half pedal stroke on a freewheel
(and nobody really does that), the "carryover" of a fixed gear will never
happen. It doesn't even happen on neighborhood bikes where the feet are not
locked to the pedals. Everybody manages to pedal through the whole circle.
If the drive of the fixed was pushing the pedals over the top, you would in
essence be backpedaling 2X for every crank revolution. That's not an
effective way to go fast.
Daniel Connelly
So, my extended interpretation of what Carl says ("undergear") is that,
ranked in order of how "forgiving" they are of low cadence, from
least to most :
* riding a fixed gear
* riding a freewheeling gear on the flats
* riding a freewheeling gear uphill, or against otherwise strong resistance
Since there are competing cost/benefit optimizations in each case, the optimal
cadence thus shifts from, say, 105 (fixed gear) to 90 (FW on the flats) to
75 (climbing).
These numbers are arbitrary, but I believe the trend is plausibly real.
Dan
Andrew Coggan
record? If the latter, I'd tell them to be more realistic...the 50% increase
in sustainable power that they'd need to be competitive is probably beyond
reach.
If the former, I'd help him maximize his power, period. If 75 rpm is
currently truly his optimum, then it is likely that he is predominantly slow
twitch, and will never pedal as fast as the average rider. Indeed, there is
no really no solid evidence that you can train your optimum rpm...
Andy Coggan
"Scott Hendricks" <sco...@MailAndNews.com> wrote in message
news:3C06...@MailAndNews.com...
Scott Anderson
> get from the guys at the velodrome (where I occasionally make an
> appearance when I'm not lazy) is that the centriputal force acting on
> the bike on the banked turn compresses the tyres more and increases
> their rolling resistance.
Yes but compressing the tyres effectively reduces the gear by the same
factor that it increases the rolling resistance so you can maintain the same
cadence and power output through the turns, only at a lower speed.
I leave the mathematical proof as an exercise...
Andrew Coggan
> Andrew Coggan <andya...@erols.com> wrote:
> > So what is your point? First time I went under the hour I also clocked a
> > 56:50...this was a non-aero, drop bar equipped (geared) road bike typical of
> > the time. Power meters weren't available back then, but I estimate that my
> > sustained power was around 350 W. Egg went just as fast in 1912, and much
> > faster in 1914, on equipment/under conditions that was (probably)
> > significantly more primitive....his power was therefore likely even higher
> > (I will look up some more accurate estimates later today to satisfy you).
>
> My point is that people with Egg-like power output were not rare
> in the early 80s and are certainly not rare now.
But may have been rare(r) in the 1930's? I don't really know one way or
another...but how does all of this relate to optimal cadence? My power, at least
when I was in my mid/late 20's, maybe have been within 10% of Egg's, but my
cadence was as well (typically, back then I TT's at 88 rpm).
If you argument is that one must pedal at 100 rpm to take the hour record, I have
only one thing to say: Graham Obree. While he clearly benefitted from his unique
aero position, he was also a stud of an athlete as well...yet averaged only, what,
93 rpm?
> I'm curious how you think Egg's equipment was significantly more
> primitive.
I'm not a cycling historian, so picturing his exact equipment is difficult for
me...it may be, though, that pneumatic tires of the time had higher rolling
resistance, and positions may not have been as aerodynamic. Unfortunately, the
couple of references I consulted did not attempt to estimate the power output of
hour record holders back that far, beginning instead with e.g., Bracke in 1967.
Andy Coggan
Theodore Heise
> So what is your point? First time I went under the hour I also clocked a
> 56:50...this was a non-aero, drop bar equipped (geared) road bike typical of
> the time. Power meters weren't available back then, but I estimate that my
> sustained power was around 350 W. Egg went just as fast in 1912, and much
> faster in 1914, on equipment/under conditions that was (probably)
> significantly more primitive....his power was therefore likely even higher
> (I will look up some more accurate estimates later today to satisfy you).
All right! He made Coggan do a Connelly.
--
Ted Heise <the...@netins.net> West Lafayette, IN, USA
Carl Sundquist
"Daniel Connelly" <djco...@ieee.org> wrote in message
news:3C051E7E...@ieee.org...
> Carl Sundquist wrote:
> >
> > Actually, it is generally recognized that you need less wattage in the
bends
> > than the straights to maintain the same speed. The reason being that
your
> > center of mass is traveling on a curve roughly 1 meter or so in radius
> > smaller than the surface where the wheels are touching. Since the
inertia of
> > your CoM is going to maintain the same speed, your wheels must travel
faster
> > to keep up with your CoM.
>
> local wind resistance).
>
> For example -- if I were to mount a massless parachute,
> and did so at the position of the hubs as opposed to from the seat,
> the effect on drag in the corners would be greater, even if my COM
position
> is unaffected.
>
I dunno. I still think that center of mass would be a greater effect than
center of drag, but I don't have any info to back it up (I was trying for
the Slingshot effect, but I don't think it necessarily applies here).
Carl Sundquist
You guys need to throw out most of what you generalize about fixed gears; it
really doesn't make a difference. As long as you are putting positive
pressure on the pedals, there is no difference whether it is fixed or
freewheel, even if you are putting out 1000 watts when the cranks are
horizontal and 10 watts when they are vertical. It doesn't matter if you are
pedaling 60 rpm or 160. Fixed gears simply allow you to perfect your
chainline and minimize friction and drag from the chain angle between the
cog and chainring, and the tension of the derailleur pulleys on the chain.
You still gotta pedal. Don't automatically associate fixed gear with high
rpm. Didn't Obree teach you anything? ;~) The main reason track riders
maintain a higher rpm is that it is easier to make changes in speed in a
smaller gear. Watching Armstrong and Ullrich riding uphill will illustrate
that.
What I would find interesting is whether sustainable power differs on flats
vs. climbing (i.e. for a given wattage, could you ride the same amount of
time on the flats as uphill? What about heartrate? Would it be different for
the same wattage if you could eliminate the cooling breeze factor? )
Robert Chung
> If 75 rpm is
> currently truly his optimum, then it is likely that he is predominantly slow
> twitch, and will never pedal as fast as the average rider. Indeed, there is
> no really no solid evidence that you can train your optimum rpm...
Man, you use ellipses like a hook. Are you saying that optimum
rpm is immutable, or that it is a dependent variable that isn't
optimizable directly but can be found out given power and gear?
--Robert Chung
Gary King
I can understand RR not such an issue with 10-11 bar tyres, but most of
us use regular clinchers with only 7 bar and the increased *weight* on
the banking (on a 250m track) while over 50km/h is noticeable
(especially on ones neck muscles holding the head up). Of course I don't
have any data on this. I'll admit I did confuse the issue. I do much of
my track riding in a train which is usually motor paced. The motorbike
is definately holding a constant speed but I must push harder through
the turns to keep smooth. Being motor paced though means riding up on
the blue line where there is a small hill every turn - explains the
extra effort..
It is all theory and no proof in the end.
Gary King
Andrew Coggan
> I can understand RR not such an issue with 10-11 bar tyres, but most of
> us use regular clinchers with only 7 bar and the increased *weight* on
> the banking (on a 250m track) while over 50km/h is noticeable
> (especially on ones neck muscles holding the head up). Of course I don't
> have any data on this. I'll admit I did confuse the issue. I do much of
> my track riding in a train which is usually motor paced. The motorbike
> is definately holding a constant speed but I must push harder through
> the turns to keep smooth. Being motor paced though means riding up on
> the blue line where there is a small hill every turn - explains the
> extra effort..
>
> It is all theory and no proof in the end.
!!
Not according to SRM recordings of power output obtained, e.g., as part of
Project 96. If you want, you can go to the SRM website and download an
example data file showing the power flucuations that occur during track
cycling (although it doesn't show you which are the straights and which are
the turns).
Andy Coggan
Gary King
> "Gary King" wrote :
> > It is all theory and no proof in the end.
>
> !!
>
> Not according to SRM recordings of power output obtained, e.g., as part of
> Project 96. If you want, you can go to the SRM website and download an
> example data file showing the power flucuations that occur during track
> cycling (although it doesn't show you which are the straights and which are
> the turns).
Then it's no use.
I want to know if it is really true that a bike rolls faster on the
turns than on the straights.
GK
Scott Hendricks
1) If a rider has a certain 'optimum' cadence when they first begin riding,
why wouldn't anyone ever try to change it, if as you say, optimum cadence
can't be trained?
2) Slower cadences require fast twitch muscle, which is counter-intuitive,
but... slower cadences require greater force per revolution, and thus
require fast twitch fibers to fire hard enough to generate the force.
Higher
cadences require less force per revolution, and therefore the less powerful,
slow twitch fibers can handle the force requirements.
That's why spinning works well to save your legs for sprinting at the end of
an event, as your fast twitch fibers will be fresher.
>===== Original Message From "Andrew Coggan" <andya...@erols.com> =====
>Is this rider training for their own personal hour record, or THE hour
>record? If the latter, I'd tell them to be more realistic...the 50% increase
>in sustainable power that they'd need to be competitive is probably beyond
>reach.
>
>If the former, I'd help him maximize his power, period. If 75 rpm is
>currently truly his optimum, then it is likely that he is predominantly slow
>twitch, and will never pedal as fast as the average rider. Indeed, there is
>no really no solid evidence that you can train your optimum rpm...
>
Robert Chung
> Well, it's not really your COM, but CO-(a more complicated function of
> local wind resistance).
>
> For example -- if I were to mount a massless parachute,
What if you were doing it in a vacuum? I often think I'm riding
around in a vacuum.
--Robert
Bob Schwartz
> Bob Schwartz wrote:
>> Andrew Coggan <andya...@erols.com> wrote:
>> > So what is your point? First time I went under the hour I also clocked a
>> > 56:50...this was a non-aero, drop bar equipped (geared) road bike typical of
>> > the time. Power meters weren't available back then, but I estimate that my
>> > sustained power was around 350 W. Egg went just as fast in 1912, and much
>> > faster in 1914, on equipment/under conditions that was (probably)
>> > significantly more primitive....his power was therefore likely even higher
>> > (I will look up some more accurate estimates later today to satisfy you).
>>
>> My point is that people with Egg-like power output were not rare
>> in the early 80s and are certainly not rare now.
> But may have been rare(r) in the 1930's? I don't really know one way or
> another...but how does all of this relate to optimal cadence? My power, at least
> when I was in my mid/late 20's, maybe have been within 10% of Egg's, but my
> cadence was as well (typically, back then I TT's at 88 rpm).
You've claimed that optimal cadence for people with stratospheric
power output != that for people with power over an hour of around
250. I don't challenge that. I mean, that's what we see if you let
time vary ie optimal cadence for max power over 200m > 4K > 1 hour.
So why wouldn't it be true holding time constant?
My point is that if you look at hour record cadence you see a
straight line all the way from the stratospheric to performances
that we would consider today to be really strong but not
outrageously so, the implication being that the curve of optimal
cadence vs max power is still pretty flat going into power outputs
that a lot of us are capable of riding at.
But if you say that there is no evidence that optimal cadence can
be trained then maybe the question is whether having a high optimal
cadence is a natural advantage in power events.
> If you argument is that one must pedal at 100 rpm to take the hour record, I have
> only one thing to say: Graham Obree. While he clearly benefitted from his unique
> aero position, he was also a stud of an athlete as well...yet averaged only, what,
> 93 rpm?
Hey, if there is one guy who puts a face on the term 'outlier', it's
Obree. I wouldn't be surprised to see contortion change optimal
cadence. But he's an interesting data point even so. His 'superman'
record cadence was 95, Boardman's was 105.
Also interesting is Anquetil. He took the record in 1956 pedaling 104
rpm, and again in 1967 slogging along at 93 rpm.
There are other problems with the data, particularly in the days before
1/2 inch pitch chain. That restricted the granularity of gear selection
such that a 24 X 7 was really the only reasonable choice.
>> I'm curious how you think Egg's equipment was significantly more
>> primitive.
> I'm not a cycling historian, so picturing his exact equipment is difficult for
> me...it may be, though, that pneumatic tires of the time had higher rolling
> resistance, and positions may not have been as aerodynamic. Unfortunately, the
> couple of references I consulted did not attempt to estimate the power output of
> hour record holders back that far, beginning instead with e.g., Bracke in 1967.
That makes sense because that's about the point where direct
comparisions got harder. People started going to Mexico and screwing
with the bike. Before that there really was only one parameter used to
break the record and that was to pedal harder.
Well, if your estimate of 350 for your TT was accurate, then 375 for Egg's
1914 ride sounds about right. I got out my copy of Hearts of Lions last
night and saw lots of pictures of people sitting on bikes pretty much the
same way that people sit on track bikes today, so I don't think position
would have been a factor. The tires were bigger though, and probably held
lower pressures.
The Lord is with the spinners Andrew! Pray for leg speed or be doomed to
mash gears throughout eternity! Whoops, wrong thread.
Bob Schwartz
cv...@execpc.com
Daniel Connelly
> If you want, you can go to the SRM website and download an
> example data file showing the power flucuations that occur during track
> cycling (although it doesn't show you which are the straights and which are
> the turns).
>
> Andy Coggan
Nice data from Liege-Bastigne-Liege, but no track data, from :
Fab5Freddy
> Carl,
>
> In the context of the present discussion, I thought it might be interesting
> if you shared your thought processes in arriving at the gear you used to
> clock that 50:18 at master nationals. In particular, do you think you could
> have cracked the 50 min barrier like you wanted to if you'd used a different
> gear? <grin>
>
> Andy Coggan
>
Gears Shmears. He would have gone sub 50 if had spent less
time out training hard on a bicycle and more time in his tent.
I'm gonna come out with a big tent - the Hypertent 2000 -
you can ride a trainer inside and then all these Master
TT records will start falling like dominos!
You'll also be able to have sex with your wives.
Scott Anderson
> > factor that it increases the rolling resistance so you can maintain the
same
> > cadence and power output through the turns, only at a lower speed.
...
> It is all theory and no proof in the end.
Actually I just made that up.
Andrew Coggan
> 2 points:
>
> 1) If a rider has a certain 'optimum' cadence when they first begin
riding,
> why wouldn't anyone ever try to change it, if as you say, optimum cadence
> can't be trained?
Do you mean, "why would anyone ever try to change it"? If so, my answer
might be "Because they don't understand physiology?"
Not to go issuing challenges, but can you point to ANY convincing data that
optimal (or even most efficient) cadence is trainable?
> 2) Slower cadences require fast twitch muscle, which is counter-intuitive,
> but... slower cadences require greater force per revolution, and thus
> require fast twitch fibers to fire hard enough to generate the force.
> Higher
> cadences require less force per revolution, and therefore the less
powerful,
> slow twitch fibers can handle the force requirements.
I assume that this is just you working your way through to the logical
conclusion, i.e., that there's no question in there?
Andy Coggan
Andrew Coggan
> You've claimed that optimal cadence for people with stratospheric
> power output != that for people with power over an hour of around
> 250. I don't challenge that. I mean, that's what we see if you let
> time vary ie optimal cadence for max power over 200m > 4K > 1 hour.
> So why wouldn't it be true holding time constant?
I'm confused by what appears to a typo in what you wrote, but I'll take a
stab at it anyway....
1) optimal cadence increases with absolute power output
2) optimal cadence decreases with exercise duration (corrolary to #1)
3) there is individual variability in the optimal cadence
So, if you take a group of cyclists that all TT at 300 W for ~ hour, then
you might find a range of optimal cadences from perhaps 75 to 95 rpm (to
just pick some numbers). There will be fewer people, though, for whom 75 rpm
is optimal when generating 350 W, and the upper end of the usual range will
also shift correspondingly upward. By the time you get to the 375-450 W
range needed to "own" the hour record, the average opitmal cadence will be
higher still. But, as Obree's success shows, there will still be individuals
who can generate the necessary power pedaling "only" ~95 rpm.
The cadences actually used by hour records over the years may not exemplify
this exact relationship...but then again, the number of hour record holders
is extremely limited, and as you point out below, other factors (e.g.,
equipment design, "tradition") may also effect things.
> But if you say that there is no evidence that optimal cadence can
> be trained then maybe the question is whether having a high optimal
> cadence is a natural advantage in power events.
We; by definition, it is: a high optimal cadence is associated with a
high(er) percentage of fast twitch muscles fibers, which does provide one
with a natural advantage in power events (sprinting, kilo).
> The Lord is with the spinners Andrew! Pray for leg speed or be doomed to
> mash gears throughout eternity! Whoops, wrong thread.
Not doomed...like the hour record holders, I, too, choose to pedal over 90
rpm when generating ~400 W. The difference is that I can only keep that up
for ~4 minutes, not one hour.
Andy Coggan
Marty Wallace
>
> "Daniel Connelly" <djco...@ieee.org> wrote in message
> news:3C051E7E...@ieee.org...
> > Carl Sundquist wrote:
> > >
> > > Actually, it is generally recognized that you need less wattage in the
> bends
> > > than the straights to maintain the same speed. The reason being that
> your
> > > center of mass is traveling on a curve roughly 1 meter or so in radius
> > > smaller than the surface where the wheels are touching. Since the
> inertia of
> > > your CoM is going to maintain the same speed, your wheels must travel
> faster
> > > to keep up with your CoM.
> >
> > Well, it's not really your COM, but CO-(a more complicated function of
> > local wind resistance).
> >
> > For example -- if I were to mount a massless parachute,
> > and did so at the position of the hubs as opposed to from the seat,
> > the effect on drag in the corners would be greater, even if my COM
> position
> > is unaffected.
> >
metres diameter, you'd be incredibly quick because your body mass would be
barely moving.
Marty Wallace
"Scott Hendricks" <sco...@MailAndNews.com> wrote in message
> 2 points:
>
> 1) If a rider has a certain 'optimum' cadence when they first begin
riding,
> why wouldn't anyone ever try to change it, if as you say, optimum cadence
> can't be trained?
That's oxymoronic.
If there's a better cadence than your "optimum cadence" then obviously it
never was your optimum cadence.
Marty
Daniel Connelly
>
> "Carl Sundquist" <car...@cox-internet.com> wrote in message
> news:u0e4g3h...@corp.supernews.com...
> >
> > "Daniel Connelly" <djco...@ieee.org> wrote in message
> > > local wind resistance).
> > >
> > > For example -- if I were to mount a massless parachute,
> > > and did so at the position of the hubs as opposed to from the seat,
> > > the effect on drag in the corners would be greater, even if my COM
> > position
> > > is unaffected.
> > >
> So taking it to extremes, if you did it on a tiny velodrome of about 3
> metres diameter, you'd be incredibly quick because your body mass would be
> barely moving.
>
> > I dunno. I still think that center of mass would be a greater effect than
> > center of drag, but I don't have any info to back it up (I was trying for
> > the Slingshot effect, but I don't think it necessarily applies here).
> >
> >
* the slingshot affect (COM) applies to acceleration. Steady-state speed is
more on wind resistance.
* WRT "tiny velodrome" -- I think a decent Hour attempt could be made with
a bike sufficiently tall that the rider is just rotating in place in the center.
It would have to be a round track. The standing start issue would be a bit
tricky... as would stopping. But post-Hour trauma is the price you gotta
pay for the glory.
Dan
Andrew Coggan
> * WRT "tiny velodrome" -- I think a decent Hour attempt could be made with
> a bike sufficiently tall that the rider is just rotating in place in the
center.
> It would have to be a round track.
Combine that idea with the notion of entertainment in the center of a six
day race, add a motor, and you have the stunt motorcyclists who whiz around
the woman at the center of the steel cage at the circus...
Andy Coggan
Henry Chang
wrote:
>
>* WRT "tiny velodrome" -- I think a decent Hour attempt could be made with
> a bike sufficiently tall that the rider is just rotating in place in the center.
> It would have to be a round track. The standing start issue would be a bit
> tricky... as would stopping. But post-Hour trauma is the price you gotta
> pay for the glory.
That would be interesting -
The UCI would have a hissy fit.
Henry
brian trdina
> time out training hard on a bicycle and more time in his tent.
> I'm gonna come out with a big tent - the Hypertent 2000 -
> you can ride a trainer inside and then all these Master
> TT records will start falling like dominos!
> You'll also be able to have sex with your wives.
C'mon dude. Most of the master's geezer crowd have been long-since divorced
because they spend all their time training instead of going down on their
old ladies. If their wrinked-up old assess were lucky enought to get some
trim, it would hafta be with some 16-22 year old minority ho trying to
finace their way through beautican school so that they'd be better equipped
to feed their multitude of little rug rats. The way I figure, it's gonna be
pretty hard to talk a minority ho into giving you a blowjob in some goofy
chamber that looks like a coffin or great big pressure cooker.
Here's a question, though: If you got out your acetylene torch and cut a
glory hole in your hyperbaric chamber, would your dick be bigger? Think
about it: If you were on the outside at a pressure of 30 in hg, but your
package was on the inside at some pressure less than 30 in hg, the result
would be more impeteus for blood to travel to your unit. In order for it to
work, you'd have to pretty much seal the hole with the rest of your body,
but I bet it would work.
Of course, there are a couple of problems with that scenario. Not the least
of which would be getting your self un-stuck (i.e, breaking vacuum) when you
decided that you'd had enough. We shoud get some of these euro-douchebags
to try it and report back about how it works.
Café-de-Colombia Latté
> Actually, it is generally recognized that you need less wattage in the bends
> than the straights to maintain the same speed. The reason being that your
> center of mass is traveling on a curve roughly 1 meter or so in radius
> smaller than the surface where the wheels are touching. Since the inertia of
> your CoM is going to maintain the same speed, your wheels must travel faster
> to keep up with your CoM. This effect isn't really noticeable on 333 and
> larger tracks. On smaller tracks, the percentage difference in radius makes
> the effect more pronounced. In other words, on a 250 track you would tend to
> float (less pressure on the pedals) in the bends to hold the same speed as
> on the straights.
>
> At the tire pressures used in an hour record attempt (11-12 bar), your tires
> are not likely to compress much more on the bends than on the straights. As
> far as I know, no one has ever mentioned sprinters bogging down in the bends
> due to increased rolling resistance and they are riding about 10 kph faster
> than an hour record speed.
>
Florida Sunkist Orange,™
Hmmm...this is strictly an engineering and physics question.
Make no mistake, going around a turn at the same speed as a straightaway
involves the rider expending/losing more energy (thus going slower). The main
reason for this conclusion, without even having to do the very compex physics
that would surely be associated with proving this, is the following:
1. The energy of the rider on a bicycle is an M = mv, where m = mass,
v=velocity, and M = Momentum. There's also an aerodynamic equation of course,
but we'll assume that's negligible since we're not debating headwind/tailwind
variables here. So, let's assume the velodrome is in a vacuum.
When you change the directional force vector of that mass, it requires an input
of energy that is being used to change the rider's directional vector that we
know is NOT being expended/lost by that same rider on a straightaway. Some
energy is lost in the tires being compressed (loss of friction and heat energy
into the velodrome and by heating the tire). This loss of efficiency does not
occur on a straightaway. There are also calculations involved in just altering
the inertia of a rider along a path of least resistance (a straighaway). There
are also about 5-10 additional forces involving complex physics when a rider
goes around a turn that is not occurring on a straightaway such as angular
momentum, moment of intertia, all kinds of friction coefficient calculations,
etc.
2. Your theory cannot be correct because it violates one of Newton's Laws,
that is: energy cannot be created or destroyed. When you use the word
"float," you are really saying there is an input of energy from somewhere other
than the rider's pedaling that makes him 'float' (because otherwise why can't
he also "float" on a straightaway? Where is the extra floating energy coming
from?), but this cannot be true because a Velodrome turn does not convert any
potential energy into kinetic energy for a rider. There MAY be some kind of
angular momentum calculation that can show leaning the bike results in lowering
the Center of Mass at an angular vector that is not perpendicular to the force
vector of gravity (as would occur on a straightaway) saves energy in some
miniscule way. But that savings would have to be offset by more energy being
expended in entering and leaving that lean because of Newton's Laws of
conservation. The calculations would be too complex to demonstrate here.
My gut feeling is that the lean angle is just plain less efficient though, and
that there is no 'float.' So turns are slower than straightaways.
I'm sure Ed Burke is the person who could definitively answer this question
with at least the theoretical calculations. But I doubt he could even use real
numbers because they would be too difficult to measure accurately. I did read
his book "The Science of Cycling" and am confident he would agree with my
overal conclusion. As a matter of fact, Burke addresses similar questions of
cycling ergonometics and physics in his book.
So I am confident that Ed Burke would say a turn slows a rider down, regardless
of any floating 'feel' a rider might experience that can be attributed to a
physiological PERCEPTION that is irrespective of the reality of the energy
expenditure numbers that physics would churn out.
Competitive track runners and their Olympic coaches will also tell you turns
slow a runner down in EVERY event (verses if the 400 or 800 meter or 5K or 10K
distance were held on a straight track.)
The physics for cycling are more complex than running because of angular
momentum equations involving the wheels and changes of the vectors and height
of the center of mass of the rider in a turn. But all of these things would
appear to yield more inefficiency and make you slower, not faster.
Rarely can you add equations to physics and get more efficiency.
You could do this experiment by taking the world class track riders and having
them go the same distance on a straight road and compare those times. The
straightaway rides would always be faster provided all the other variables were
controlled properly.
Café
The Trexlertown Experiment
Scott Hendricks
portion of your previous message I was referencing, but that you omitted
here,
you stated that since a rider had a slow 'optimum cadence' he likely
possessed
mostly slow twitch fibers. I was pointing out, without just flat out saying
you were "WRONG" as so many folks who frequent the group would've done, that
you had it backwards.
As for whether you can train your optimum cadence, I "believe" that there
are
ways to train efficiency at various cadences. Otherwise, it would be as
simple as doing a little testing once you start riding, and if your optimum
cadence isn't somewhere between 85 - 105, you may as well decide to just
give
up on the idea of becoming a bike racer. I mean, all good racers pedal
within
that range, right??? If you can't/don't, pick another sport, right???
>===== Original Message From "Andrew Coggan" <andya...@erols.com> =====
>Scott Hendricks wrote:
>
>
>> 2) Slower cadences require fast twitch muscle, which is counter-intuitive,
>> but... slower cadences require greater force per revolution, and thus
>> require fast twitch fibers to fire hard enough to generate the force.
>> Higher
>> cadences require less force per revolution, and therefore the less
>powerful,
>> slow twitch fibers can handle the force requirements.
>
Carl Sundquist
class at that, so I can't argue physics with you in a mathematical equation
(I just scraped by on differential equations), but I can cite real world
phenomena which present similarities in function.
With an acknowledgement that there are some differences, how would the CoM
as I described it differ from a hammer thrown into the air? It doesn't spin
around its midpoint of length, it's spin axis is much closer to the head of
the hammer. Also, the drag caused by the greater speed of the handle does
not overcome the mass of the hammerhead and cancel out or reverse the axis
of the spinning hammer, nor is the drag of the hammerhead the cause of the
axis point. You could put something equal to the surface area of the
hammerhead (but massless) on the end of the handle and it would still spin
around the hammerhead.
Basing my theory on that example, remember that it is the contact point of
the wheel/track which I refer to as maintaining the same speed. Initially,
as the rider enters the turn the wheels must accelerate, like the handle of
the hammer once it is released from your hand. The hammerhead maintains
(more or less) the same velocity as when released from your hand, but the
handle must accelerate around it as the hammer rotates. The revolutions are
the same (bike and rider as one), but being a greater distance from the
center of the turn, the wheels' speed is faster. In order for the wheels to
try to hold the same speed in the turns as on the straights, the rider's CoM
must actually slow down for the wheels to hold a constant speed. This is
where the rider floats. The rider will then have to "punch it" a bit once
they reenter the straight in order to get their body mass back up to wheel
speed. These changes are slight, otherwise everyone would try records on
larger and larger velodromes, to negate the energy demands of accelerating
and decelerating repeatedly.
Mind you, the whole purpose of riding steady speed is for the sake of an eve
nt like team pursuit or behind a derny where fluctuations in speed cause the
team to look like a Slinky, a bad thing. You can actually hear the change
in rpms on a derny as it goes on the straights and turns. If you kept a
constant power output on a paceline of riders at high speed, as I said
before, you would have an accordion effect where each person would open up a
slight gap on the following rider as their bike speeds up going into the
turn before the following rider reaches the turn and so on down the line,
with the whole line stretching out as each rider enters the turn. Then, once
they hit the straight, the line would compress and the following riders
would each have to move slightly to the right, across the width of the
track, to avoid hitting wheels with rider in front of them who's bike has
slowed down to keep pace with the rider's CoM. For a team pursuit, this
looks quite silly and amateurish.
For individual events, clearly it is much more efficient to put out a
constant power level and let the wheel speed vary slightly.
Also, riding on a round velodrome would negate the effect entirely, as it is
only in the turn/straight transition where the speed changes occur. And we
could open a whole new thread on max speeds vs. velodrome size and turn
radius because you simply can't ride as fast on a small track as a big track
(within reason, of course).
Sometimes you actually have to experience things to realize which concepts
and laws apply to a given situation.
Café-de-Colombia Latté" <java...@cafe.com> wrote in message
news:3C0B4E67...@cafe.com...
Carl Sundquist
have to "punch it" to keep the wheels from slowing down to the speed of the
CoM. By "punching it" I mean increasing power not only to get back to steady
straight speed-power, but even more power to accelerate the CoM up to wheel
speed.
Carl Sundquist
reasons:
1. Cyclists are optimally within a few degrees of perpendicular at speed.
Runners, particularly the sprints, are far from perpendicular. That's why
small radiussed indoor running tracks have some token gesture of banking.
2. What are the effects of G forces on runners in turns? Do you think that
their means of propulsion also being their means of bearing their bodyweight
might have something to do with it? As a side note: you *never* see a rider
even close to max speed out of the saddle in a turn. You just can't do it.
The means of vector change on a velodrome are achieved by a mechanical
device (the bike) and for the most part have little to do with diminishing
speed.
Incidentally, if you were to spin a wheel as fast as you could in your hands
then release it to go around the pole line (or any other line) on a well
designed velodrome, it will follow that line. Due to the banking, it will
not try to go in a straight line, not follow the track and hit the
balustrade (outside wall). It will follow the pole line around to the next
straight. Only the drag of wind resistance, rolling resistance, and gravity
will cause it to eventually slow down and roll into the infield.
Café-de-Colombia Latté" <java...@cafe.com> wrote in message
news:3C0B4E67...@cafe.com...
> Competitive track runners and their Olympic coaches will also tell you
Benjamin Weiner
> from?), but this cannot be true because a Velodrome turn does not convert any
> potential energy into kinetic energy for a rider. There MAY be some kind of
> angular momentum calculation that can show leaning the bike results in lowering
> the Center of Mass at an angular vector that is not perpendicular to the force
> vector of gravity (as would occur on a straightaway) saves energy in some
> miniscule way. But that savings would have to be offset by more energy being
> expended in entering and leaving that lean because of Newton's Laws of
> conservation. The calculations would be too complex to demonstrate here.
> ... Rarely can you add equations to physics and get more efficiency.
Too Much Coffee Man,
About this physics thing. Don't quit your day job.
-Ben
Rocket Scientist
P.S. http://www.analyticcycling.com/genmodel/LeanAnalysis.html
and
http://www.tmcm.com/
Daniel Connelly
> P.S. http://www.analyticcycling.com/genmodel/LeanAnalysis.html
Tom makes the mistake of using center of mass alone, and not center
of wind resistance for the aerodynamic drag, as was previously discussed.
It's probably a decent approximation, however.
GBSHAUN
I believe the CoM maintains a constant speed (consevation of momentum). The
part of the bike/rider that is inboard of this point is what slows down, and by
an amount proportional to it's distance from that CoG plane.
Certainly there are frictional losses from riding through a tight bend, and the
rider probably can't maintain such a level of power output with such forces,
but the gains are the periodic accelerations going into the bends which,
although countered by an equivalent deceleration coming out, will result in a
higher net speed given a constant power production.
So small tracks can be faster, and the maths is not difficult IF the power
output was not affected.
>
>For individual events, clearly it is much more efficient to put out a
>constant power level and let the wheel speed vary slightly.
>
This is where I'd disagree.
IMO it is far less fatiguing to be able to let the legs relax for a second or
so, even if it means "punching" it as you correctly mention as you exit the
bend.
I think it was a technique of Eddy B's where a TT rider would relax for a pedal
revolution every 7 or so.
On a velodrome, the convenient place for this relaxation is approaching the
apex of the bend because 1) The speed (and cadence) is already increasing,
which does cause a problem for our coordination of producing power (easier to
"coast")
and 2) the extra forces in the bend would mean we'd need to modify our muscle
contractions somewhat if we are to continue with the same power, even if it's
just because we sink into the saddle further.
So the bend is a convenient place for this, plus one where there are extra
reasons for doing so.
For me, Stuttgart's "long" 285m track had the ideal ratio of bend to
straightaway.
It is for the same reason that i generally train at the top of the (333m)
track. I can maintain an average power output much longer there than at the
bottom. I'm sure others could do to.
A rider guages his speed by the cadence, which is tied directly into the wheel
speed. So the rider feels the whole bike/rider combination is
accelerating/decelerating.
This doesn't HAVE to be a problem for a team pursuit, as long as the riders
accepted that the rider ahead will accelerate away as he enters the bend first,
knowing that he will "come back" as they enter the bend. It might even be
useful for swing-off clearance. So long as the following rider doesn't
artificially try to maintain the close distance as they go into the bend, and
so then have to decelerate unnaturally as they leave. All riders would have to
have a similar profile of varying the power. I'll bet this is what happens
anyhow rather than all 4 riding at constant power.
>Also, riding on a round velodrome would negate the effect entirely, as it is
>only in the turn/straight transition where the speed changes occur. And we
>could open a whole new thread on max speeds vs. velodrome size and turn
>radius because you simply can't ride as fast on a small track as a big track
>(within reason, of course).
>
One final advantage of small tracks: You get more aerodynamic benefit from
riding in your own wake. On a 6-day track there's a regular tailwind.
The track in Buenos Aires was so small that, if you looked up as you came out
of the bend, you could just catch a gimpse of your own back wheel vanishing
into the corner ahead of you :-)
Shaun Wallace
Andrew Coggan
> I'm sorry, I expected that you could draw the obvious conclusion. In the
> portion of your previous message I was referencing, but that you omitted
> here,
> you stated that since a rider had a slow 'optimum cadence' he likely
> possessed
> mostly slow twitch fibers. I was pointing out, without just flat out saying
> you were "WRONG" as so many folks who frequent the group would've done, that
> you had it backwards.
No, you are the one that has it backwards...do I need to trot out the specific
reference to demonstrate that fact? (Hint: the study involved trained cyclists,
trained runners, and untrained subjects.)
> As for whether you can train your optimum cadence, I "believe" that there
> are
> ways to train efficiency at various cadences. Otherwise, it would be as
> simple as doing a little testing once you start riding, and if your optimum
> cadence isn't somewhere between 85 - 105, you may as well decide to just
> give
> up on the idea of becoming a bike racer. I mean, all good racers pedal
> within
> that range, right??? If you can't/don't, pick another sport, right???
As I stated, there is no solid evidence that one can alter their optimal cadence
via training. I challenge you come up with any scientific studies showing
otherwise.
Andrew R. Coggan, Ph.D.
Philip Holman
hands
> then release it to go around the pole line (or any other line) on a well
> designed velodrome, it will follow that line. Due to the banking, it will
> not try to go in a straight line, not follow the track and hit the
> balustrade (outside wall). It will follow the pole line around to the next
> straight. Only the drag of wind resistance, rolling resistance, and
gravity
> will cause it to eventually slow down and roll into the infield.
>
be normal with the banking.
The party trick you are suggesting can be made to work on any track or even
a flat surface for that matter. The precession rate (turning rate) of a
wheel is determined from the torque resulting from its lean angle divided by
its gyroscopic moment and has nothing to do with whether a track is well
designed or not.
Phil Holman
Benjamin Weiner
> I believe the CoM maintains a constant speed (consevation of momentum). The
> part of the bike/rider that is inboard of this point is what slows down, and by
> an amount proportional to it's distance from that CoG plane.
> Certainly there are frictional losses from riding through a tight bend, and the
> rider probably can't maintain such a level of power output with such forces,
> but the gains are the periodic accelerations going into the bends which,
> although countered by an equivalent deceleration coming out, will result in a
> higher net speed given a constant power production.
> So small tracks can be faster, and the maths is not difficult IF the power
> output was not affected.
Okay, in the interest of having a serious discussion (why the
hell not), I tried to do a simple calculation of what happens
in the curve. I don't think conservation of momentum is the
final answer because there are forces from the rider, air and
track. Earlier I posted an analyticcycling.com URL.
That is much more sophisticated but doesn't really explain
what happens step by step. Excuse all the math - it's my job.
I think there are three important factors, all caused by the lean:
1) rider travels slower than wheels in the curve so air
resistance is less for the same wheel speed
2) rider pulls more than one G so normal force is greater
and rolling resistance is greater
3) the lean lowers the rider's center of mass, so he/she effectively
descends on entering the turn and climbs on leaving it.
Let's assume a speed of 13 m/s constant through the turn, rather
than constant power, because it's easier to calculate with.
Also a lean angle of 0 in the straight and theta=45 degrees in the
turn, and turn radius of 25 m. (Actually we could calculate
the lean angle from the speed, radius and banking, but that's
too much bother.) Also assume the rider's center of mass
and center of wind resistance are 1.1 meters above the ground.
1. Air drag. The rider travels in a radius less than the tires by
1.1*sin(theta) m. As the tires move at 13 m/s the rider moves at
12.6 m/s. For rider area 0.6 m^2, drag coeff 0.5,
P=0.5 C_D A rho_air (v_rider)^3,
Power in straight = 404 W (this is only power used to overcome air drag)
Power in turn = 368 W
2. Rolling resistance. The force of gravity on the rider points
straight down. This has to be counteracted by the normal force
from the ground up through the tire at the lean angle. When the
rider is leaned over, total normal force is higher since there is
a component perpendicular to gravity. F_normal = mg / cos(theta).
For rider+bike weight 90 kg, coeff of rolling resistance 0.003
(could be even lower?), and P = C_rr F_normal v_tire,
RR Power in straight = 34 W
RR Power in turn = 49 W
3. "Descending" from lean. As the rider leans over he gains
energy (from potential energy). Of course he has to give it
back on exiting the turn. The center of mass descends by
1.1m * (1-cos(theta), or 0.32 m when leaning from 0 to 45 degrees.
Potential energy is PE=mgh.
Energy change from lean = 282 Joules
The lean probably happens in a second or less so it's like
a one-second kick of 282 W (or subtraction of same). Oof.
So for this set of assumptions the rider saved 21 watts
in the turn (air drag gain, rolling resistance loss) to
maintain constant speed. Time through the turn is
(25*pi)/13 = 6.04 sec so an energy savings of P*t = 127 Joules.
It looks like the turn is faster than the straight due
to the decreased air resistance. But comparing the energy
contributions, what dominates the acceleration and
deceleration on entering/exiting is the work done by
gravity on the leaning rider.
Flame away if you feel I've done something wrong
(but don't anybody read all the way through this
only to tell me I'm a geek. I _know_ that. And
like I said, it's my job.)
Ben
GBSHAUN
>Date: 12/4/2001 7:03 PM Pacific Standard Time
>Message-id: <3c0d8e8a$1...@news.ucsc.edu>
Good stuff Ben
Certainly all those things affect the power required. But how about the fact
that, if the wheels move at the same 13m/sec as in your example, then the C of
Mass (assuming the same 1.1m from the wheels) is only going the 12.6m/sec, and
thus the kinetic energy is reduced in that second as well as the potential
energy.
Multiplying out the kinetic energy (= 1/2 mv**2) gives a reduction of about
460J. Which would mean totally coasting for 1 second to achieve.
How about we look at a model where the rider's center of mass and wind
resistance stays at a constant velocity, and the wheel velocity increases?
The momentary gain would be from the potential energy (lean) that is reduced,
but more power would be required for the tyre drag.
Of course it would be simpler if we could just agree to ignore these two
factors!
Shaun
******************************************************
GBSHAUN
>cadence
>via training. I challenge you come up with any scientific studies showing
>otherwise.
>
>Andrew R. Coggan, Ph.D.
>
I trust you're not suggesting there's not plenty of anecdotal evidence?
Out of season i could barely attain the cadence which, in season, i would
choose to pursuit at.
Shaun Wallace
Ralph Dilts
"GBSHAUN" <gbs...@aol.com-Wallace> wrote in message
news:20011204230254...@mb-cg.aol.com...
I think there is an error here. The "energy change" from the lean will not
produce any change in velocity or momentum as long as the surface along
which the bike travels remains level. The bike will exert less force
against the track while leaning over, and more when straightening up, but as
long as that force is all normal to the surface it will neither accelerate
or decelerate the rider. Jumping up and down will neither speed up nor slow
down (aside from the changing contribution to wind resistance) your bicycle
as long as you are riding on a level surface.
> >
> >So for this set of assumptions the rider saved 21 watts
> >in the turn (air drag gain, rolling resistance loss) to
> >maintain constant speed. Time through the turn is
> >(25*pi)/13 = 6.04 sec so an energy savings of P*t = 127 Joules.
> >It looks like the turn is faster than the straight due
> >to the decreased air resistance. But comparing the energy
> >contributions, what dominates the acceleration and
> >deceleration on entering/exiting is the work done by
> >gravity on the leaning rider.
But the "energy contibution" of leaning does nothing to accelerate or
decelerate the rider - so try again.
> >
> >Flame away if you feel I've done something wrong
> >(but don't anybody read all the way through this
> >only to tell me I'm a geek. I _know_ that. And
> >like I said, it's my job.)
> >
> >Ben
> >
>
> Good stuff Ben
> Certainly all those things affect the power required. But how about the
fact
> that, if the wheels move at the same 13m/sec as in your example, then the
C of
> Mass (assuming the same 1.1m from the wheels) is only going the
12.6m/sec, and
> thus the kinetic energy is reduced in that second as well as the potential
> energy.
> Multiplying out the kinetic energy (= 1/2 mv**2) gives a reduction of
about
> 460J. Which would mean totally coasting for 1 second to achieve.
> How about we look at a model where the rider's center of mass and wind
> resistance stays at a constant velocity, and the wheel velocity increases?
> The momentary gain would be from the potential energy (lean) that is
reduced,
No gain because of the direction of the action of the force. - but a more
likely real world scenario.
> but more power would be required for the tyre drag.
> Of course it would be simpler if we could just agree to ignore these two
> factors!
>
> Shaun
>
>
Ralph Dilts
Not a mathemetician, but an engineer.
Benjamin Weiner
> I think there is an error here. The "energy change" from the lean will not
> produce any change in velocity or momentum as long as the surface along
> which the bike travels remains level. The bike will exert less force
> against the track while leaning over, and more when straightening up, but as
> long as that force is all normal to the surface it will neither accelerate
> or decelerate the rider. Jumping up and down will neither speed up nor slow
> down (aside from the changing contribution to wind resistance) your bicycle
> as long as you are riding on a level surface.
Actually I think this is ok, because it happens in
a turn. The normal force from the track on the bike
has a component that points inward, which provides
the centripetal acceleration necessary to keep the
wheels going round the curve. As this acceleration
changes, the bike's speed can change (a = v^2/r)
even though the normal force vector is perpendicular
to the instantaneous direction of motion. Counterintuitive
but true.
Many of us have probably done the experiment where you
swing a mass on a string and pull harder to speed up the
circular motion. (I vaguely recall a teaching apparatus that
pulls a string through the axis of a turntable, although
that changes radius as well.)
I didn't try to analyze what happens as the bike enters the turn
and is leaned over, and how the normal force changes dynamically
and torques the bike to lean it over. It was just too complicated.
I'll admit here that Tom Compton's Analytic Cycling page
http://www.analyticcycling.com/genmodel/LeanAnalysis.html
says that the potential energy is converted to speed, and if
I hadn't seen that second opinion, I might not have been bold
enough to post the analysis. If Tom is lurking out there
I'd like to hear his thoughts.
> Ralph Dilts
> Not a mathemetician, but an engineer.
I'm not a mathematician either. IME, engineers and physicists
can make these problems difficult enough!
Ben
Andrew Coggan
I assume you're exaggerating for effect...even an untrained person can
achieve a cadence of >150 rpm, i.e., higher than you would ever choose to
pursuit at. But, be that as it may, a pursuit is not a personal hour record
attempt, which is what we were talking about here.
Andy Coggan
GBSHAUN
Ok, I should have used the word "maintain". I was thinking of 125 rpm for 5
minutes which, out of season, I'd find hard on my own in any gear.
Even when talking about the hour record, which is done at about 100rpm, I would
be surprised if you were inferring that training could not alter their optimal
cadence. 100 rpm is still higher than most riders are comfortable at
maintaining for an extended period.
I accept that there are probably no studies showing the effect, which is what
you were actually claiming.
Shaun Wallace
Philip Holman
"Benjamin Weiner" <b...@isis.ucolick.org> wrote in message
news:3c0de457$1...@news.ucsc.edu...
> Ralph Dilts <red...@home.com> wrote:
>
> > I think there is an error here. The "energy change" from the lean will
not
> > produce any change in velocity or momentum as long as the surface along
> > which the bike travels remains level. The bike will exert less force
> > against the track while leaning over, and more when straightening up,
but as
> > long as that force is all normal to the surface it will neither
accelerate
> > or decelerate the rider. Jumping up and down will neither speed up nor
slow
> > down (aside from the changing contribution to wind resistance) your
bicycle
> > as long as you are riding on a level surface.
>
> Actually I think this is ok, because it happens in
> a turn. The normal force from the track on the bike
> has a component that points inward, which provides
> the centripetal acceleration necessary to keep the
> wheels going round the curve. As this acceleration
> changes, the bike's speed can change (a = v^2/r)
> even though the normal force vector is perpendicular
> to the instantaneous direction of motion. Counterintuitive
> but true.
When considering the velocity at the center of mass for leaning a bike in a
turn:
Speed does change as KE + PE (1/2mv^2 + mgh) when converted back into all KE
will give a velocity increase of about 1/2 mph for a 200lb mass at 30mph and
45 deg. lean. The centripetal acceleration will not result in any increase
but just changes the direction component of momentum. (i.e. along the axis
of rotation or circular motion).
This increase in velocity will tend to be scrubbed off with increase in
rolling resistance and increase in aerodynamic drag and will be almost back
to 30mph at the end of the turn. Coming out of the turn the speed will
decrease by 1/2 mph and hence a need to increase power output slightly to
maintain 30mph.
This falls in line with what riders experience and have stated here.
>
> Many of us have probably done the experiment where you
> swing a mass on a string and pull harder to speed up the
> circular motion. (I vaguely recall a teaching apparatus that
> pulls a string through the axis of a turntable, although
> that changes radius as well.)
>
> I didn't try to analyze what happens as the bike enters the turn
> and is leaned over, and how the normal force changes dynamically
> and torques the bike to lean it over. It was just too complicated.
>
Its not very complicated. Gravity does the work so the PE change in leaning
the bike over is converted into KE with an increase in speed. And on
returning to an upright position KE gets converted back into PE with a loss
of speed.
Momentum is conserved in translating from linear to circular motion.
> I'll admit here that Tom Compton's Analytic Cycling page
> http://www.analyticcycling.com/genmodel/LeanAnalysis.html
> says that the potential energy is converted to speed, and if
> I hadn't seen that second opinion, I might not have been bold
> enough to post the analysis. If Tom is lurking out there
> I'd like to hear his thoughts.
>
> > Ralph Dilts
> > Not a mathemetician, but an engineer.
>
> I'm not a mathematician either. IME, engineers and physicists
> can make these problems difficult enough!
Its not these people who make this difficult ........ reality is what it is.
Phil Holman
Benjamin Weiner
> Certainly all those things affect the power required. But how about the fact
> that, if the wheels move at the same 13m/sec as in your example, then the C of
> Mass (assuming the same 1.1m from the wheels) is only going the 12.6m/sec, and
> thus the kinetic energy is reduced in that second as well as the potential
> energy.
> Multiplying out the kinetic energy (= 1/2 mv**2) gives a reduction of about
> 460J. Which would mean totally coasting for 1 second to achieve.
Well, the rider is now going around the curve, so there
is an acceleration acting, and just computing the KE of
his center of mass is presumably incomplete since it's
not linear motion. But I agree, it's unrealistic that
the wheels would maintain the same speed. I only
computed it that way because it was simpler. We could
assume constant power, but then we'd have to solve an
(cubic?) equation to get the new wheel speed.
> How about we look at a model where the rider's center of mass and wind
> resistance stays at a constant velocity, and the wheel velocity increases?
> The momentary gain would be from the potential energy (lean) that is reduced,
> but more power would be required for the tyre drag.
> Of course it would be simpler if we could just agree to ignore these two
> factors!
> Shaun
> ******************************************************
> http://www.altitudetent.com
Well, using the numbers I gave earlier, if the rider's
c-of-m continues to move at 13 m/s, the wheel speed
goes up to 13.4 m/s, and the rolling resistance power goes
up by a factor 1.03 (and the factor 1.41 for the lean),
so from 34 W in the straight to 50 W in the turn.
Then an extra 16 W is required and 0.2 sec is gained in
the turn.
That's for a C_rr=0.003. You could decrease the extra power
with a lower C_rr (assume the bicycle has steel wheels - ouch).
Phil Holman
> GBSHAUN <gbs...@aol.com-Wallace> wrote:
>
> > Certainly all those things affect the power required. But how about the fact
> > that, if the wheels move at the same 13m/sec as in your example, then the C of
> > Mass (assuming the same 1.1m from the wheels) is only going the 12.6m/sec, and
> > thus the kinetic energy is reduced in that second as well as the potential
> > energy.
> > Multiplying out the kinetic energy (= 1/2 mv**2) gives a reduction of about
> > 460J. Which would mean totally coasting for 1 second to achieve.
>
> Well, the rider is now going around the curve, so there
> is an acceleration acting, and just computing the KE of
> his center of mass is presumably incomplete since it's
> not linear motion.
1/2mv^2 (linear) converts to (1/2Iw^2) circular with no losses. The
acceleration is a change in direction with no forces opposing forward
motion.
Phil Holman
GBSHAUN
>From: Benjamin Weiner b...@isis.ucolick.org
>
>Well, using the numbers I gave earlier, if the rider's
>c-of-m continues to move at 13 m/s, the wheel speed
>goes up to 13.4 m/s, and the rolling resistance power goes
>up by a factor 1.03 (and the factor 1.41 for the lean),
>so from 34 W in the straight to 50 W in the turn.
>Then an extra 16 W is required and 0.2 sec is gained in
>the turn.
>
And what a deal that is!
Even if we gave up half of that gain for the extra drag (not far off), assuming
a constant power output, that would gain us a total of 0.8 seconds per
kilometer on a 250 m track, or an extra lap in a hour.
Shaun