Power Profiling -- good stuff

"Robert Chung" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Estimating CdA from open air field tests is kinda difficult, though Allen Lim claims to be able to
do it. I'm skeptical, though of course I'm not privy to his data.

He presented some data in an abstract at the American College of Sports Medicine meetings in early
June. As predicted on the wattage list, despite using a rather unique venue (i.e., a large aircraft
hangar) the precision wasn't as good as what you can achieve in a wind tunnel, and in fact was no
better than what I found in my experiments (see below)

Quoted message said:

I went through a little exercise on the wattage list a few months ago with a guy who had some
power data and was trying to estimate CdA from it. Even though the data were moderately clean
the coefficient of variation was kinda high. Andy has done some stuff on trying to calculate CdA
from a rider in a velodrome (I *think* it might have been an outdoor velodrome rather than an
indoor one).

Correct: I used data collected at Alkek and Trexlertown. Coefficient of variation for repeated
2 km trials was ~2%...about the same as Lim reported, and still not good enough to be
particularly helpful.

More recently, I've conducted three days of testing using Lim's approach of mulitple speed trials to
separate CdA and Crr...despite doing the testing very early in the morning on very flat roads,
precision was again only about 2%. One impressive finding from these experiments was how little wind
it takes to really skew the results - for example, on a day so calm that a tiny piece of dry leaf
dropped from overhead falls to the ground less than 1 foot from vertical, there are still
significant differences in estimated CdA depending on whether you are headed "upwind" or "downwind".
Similary, trials conducted less than a full minute after a vehicle passes down the road at ~30 mph
also produce abnormally high or low values, depending on whether the trial was in the same direction
or the opposite direction in which the vehicle passed.

Andy Coggan

Andy Coggan said:

"Robert Chung" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

CdA would vary roughly with m^(.2). A 25% difference in mass gives a 5% difference in CdA?

Heil concluded that Cd must vary with mass^-0.45 because of experimental observations that CdA
varies with mass^0.33 (or thereabouts).

So if CdA varies with m^0.33, then a 25% difference in mass gives a 7.5% difference in CdA?

"Robert Chung" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Andy Coggan said:

"Robert Chung" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

CdA would vary roughly with m^(.2). A 25% difference in mass gives a 5% difference in CdA?

Heil concluded that Cd must vary with mass^-0.45 because of experimental observations that CdA
varies with mass^0.33 (or thereabouts).

So if CdA varies with m^0.33, then a 25% difference in mass gives a 7.5% difference in CdA?

I know that's a rhetorical question, but the answer is yes: all else (e.g., height, position) being
equal, a 25% increase in mass theoretically results in only a 7.5% difference in CdA. I believe that
makes sense if you think about it...for example, if I gained 37.5 lbs I'd be a true masters fattie,
but I wouldn't be *that* much wider or higher (assuming I could still get down on the aerobars w/ a
big belly in the way).

Andy Coggan

"Kurgan Gringioni" <[email hidden]> wrote in message
news:<[email hidden]>...

<snip>

Quoted message said:

Quoted message said:

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I don't know if you watched the pro1/2 Socal races after your races (I'm assuming you're
master), but notice how Paolinetti was always forearms

on

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the handlebar in breakaways, even through turns? He had that figured

out.

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In fact I was on Jamie's team in 1997 and had the pleasure of watching (from the comfort of the
peloton) him win the Manhattan Beach GP in a break. You are right; he slices through the air
really well.

Damn, you were on that team? Email me in private if you wish, I've got an apocryphal thing to
relate from that year.

Thanks, but no thanks (and no offense intended). I have one lasting memory of that team and year
that I will take to my grave. On July 6th 1997, in a matter of moments, I went from an endorphin-
and adrenalin-fueled euphoria at being in the (potentially) winning break over a high-quality field,
to an immediate emotional devestation and shock when the race was stopped and I was told that a
teammate had died of injuries suffered in a crash earlier in the race. I really don't need to learn
anything more about that year, especially if it is negative.

Quoted message said:

The reason I thought you were a Master is because of the Longo Visalia story you related.

You are correct; I do race Masters now, almost exclusively.

Mark

Andy Coggan said:

"Robert Chung" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Estimating CdA from open air field tests is kinda difficult, though Allen Lim claims to be able
to do it. I'm skeptical, though of course I'm not privy to his data.

He presented some data in an abstract at the American College of Sports Medicine meetings in early
June. As predicted on the wattage list, despite using a rather unique venue (i.e., a large
aircraft hangar) the precision wasn't as good as what you can achieve in a wind tunnel, and in
fact was no better than what I found in my experiments (see below)

I know I shouldn't do this, but I can't help it. In case Warren thinks Andy is exaggerating Allen
Lim's claim about wind tunnels, the exact quote is, "it's our belief that the aerodynamic and
rolling resistance values we calculate in the real world using the Power Tap are more accurate than
a wind tunnel."

You can find that quote about three-quarters of the way down this bike.com article:
bike.comtemplate.aspOpen ↗

In article said:

Andy Coggan said:

"Robert Chung" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Estimating CdA from open air field tests is kinda difficult, though Allen Lim claims to be able
to do it. I'm skeptical, though of course I'm not privy to his data.

He presented some data in an abstract at the American College of Sports Medicine meetings in
early June. As predicted on the wattage list, despite using a rather unique venue (i.e., a large
aircraft hangar) the precision wasn't as good as what you can achieve in a wind tunnel, and in
fact was no better than what I found in my experiments (see below)

I know I shouldn't do this, but I can't help it. In case Warren thinks Andy is exaggerating Allen
Lim's claim about wind tunnels,

No I don't think that. My experience yesterday with a wind of maybe 2-3mph showed a range of about
.75m2 to .9m2 so I can't see how one could achieve +/- 2% accuracy with "no" wind.

Quoted message said:

the exact quote is, "it's our belief that the aerodynamic and rolling resistance values we
calculate in the real world using the Power Tap are more accurate than a wind tunnel."

Hard to believe somebody would even say that-especially when they're relying on a PT.

-WG

In article <[email hidden]>, Andy Coggan

Quoted message said:

"warren" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Quoted message said:

I cheated by recalling an article in VeloNews from years back about two guys who claimed they
could predict TT times based on the riders' wattage output and their aero drag. Whatever
happened to those guys?

Maybe these guys? www.pkracing.com (I hope that URL is correct.)

Actually I remembered it as being you and Jim Martin. Guess not.

Quoted message said:

Quoted message said:

Last night I did a little test on a perfectly flat road, 26.5 mph, 1 minute, back and forth once
each. There was a very slight wind and my efa numbers according to his calculations were .75 and
.90 (tailwind and headwind).

You *really* need to subscribe to the wattage list...

I've been lurking off the Topica website but I have to wade through alot of talk about hardware
issues and time trialing-neither of which interest me that much. There are some pearls there though.

Quoted message said:

Bottom line: while *very careful* field testing can yield fairly precise numbers for CdA (i.e.,
coefficient of variation of ~2%), it still really isn't good enough to be of much use (e.g., for
choosing equipment, or even optimizing position).

I was just trying to get a ballpark for my frontal area and to compare my Polar power readings with
his caluclations.

Quoted message said:

That's why I'm going back to the wind tunnel this winter...anybody want to join me?

Curious, what does that cost?

-WG

Ten tries upwind and down. Record each. The drag coefficient should then be pretty predictable given
the DIFFERENCE in times and the wind speed.

"Robert Chung" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

warren said:

I cheated by recalling an article in VeloNews from years back

about two

Quoted message said:

Quoted message said:

guys who claimed they could predict TT times based on the riders' wattage output and their aero
drag. Whatever happened to those

guys?

Quoted message said:

I agree, you can do a good job predicting TT times based on wattage

and

Quoted message said:

aero drag; but what you wrote upthread was that if you know wattage

and

Quoted message said:

*weight* someone could predict TT times. Someone could -- I just

think the

Quoted message said:

prediction wouldn't be as good as wattage and aero drag.

Quoted message said:

At Analytic Cycling he uses "effective frontal area" measured in

square

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meters for aero drag. I'm curious if you can calculate reasonably

well

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this based on rider height and weight. He says typical values are

.4 to

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.7 m2. Last night I did a little test on a perfectly flat road,

26.5

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mph, 1 minute, back and forth once each. There was a very slight

wind

Quoted message said:

Quoted message said:

and my efa numbers according to his calculations were .75 and .90 (tailwind and headwind).

Estimating CdA from open air field tests is kinda difficult, though

Allen

Quoted message said:

Lim claims to be able to do it. I'm skeptical, though of course I'm

not

Quoted message said:

privy to his data. I went through a little exercise on the wattage

list a

Quoted message said:

few months ago with a guy who had some power data and was trying to estimate CdA from it. Even
though the data were moderately clean the coefficient of variation was kinda high. Andy has done
some stuff on trying to calculate CdA from a rider in a velodrome (I *think* it

might

Quoted message said:

have been an outdoor velodrome rather than an indoor one).

"warren" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

In article said:

Andy Coggan said:

"Robert Chung" <[email hidden]> wrote in message
"]news:[email hidden]...

> Estimating CdA from open air field tests is kinda difficult, though Allen Lim claims to be
> able to do it. I'm skeptical, though of course I'm not privy to his data.

He presented some data in an abstract at the American College of

Sports

Quoted message said:

Quoted message said:

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Medicine meetings in early June. As predicted on the wattage list, despite using a rather
unique venue (i.e., a large aircraft hangar)

the

Quoted message said:

Quoted message said:

Quoted message said:

precision wasn't as good as what you can achieve in a wind tunnel, and in fact was no better
than what I found in my experiments (see below)

I know I shouldn't do this, but I can't help it. In case Warren thinks Andy is exaggerating
Allen Lim's claim about wind tunnels,

No I don't think that. My experience yesterday with a wind of maybe 2-3mph showed a range of about
.75m2 to .9m2 so I can't see how one could achieve +/- 2% accuracy with "no" wind.

A wind of 2-3 mph is actually quite significant in this context, as I tried to relate. Be that as
it may, your results may be better than you think. With a reasonable sample size, the SD is
usually about half the range, so assuming that 0.75-0.90 m^2 reflects the limits, then you're
already under 10%. .

Quoted message said:

Quoted message said:

the exact quote is, "it's our belief that the aerodynamic and rolling resistance values

we

Quoted message said:

Quoted message said:

calculate in the real world using the Power Tap are more accurate than a wind tunnel."

Hard to believe somebody would even say that-especially when they're relying on a PT.

If I had to trust the numbers from any power meter completely blindly, w/o calibrating it myself,
I'd pick a PowerTap over an SRM (esp. the Amateur) or Polar. That's especially true in this context,
since what you really want to know if power delivered to the rear wheel/road, not the power the
rider actually produces.

Andy Coggan

"warren" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

In article <[email hidden]>, Andy Coggan

Quoted message said:

"warren" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Quoted message said:

I cheated by recalling an article in VeloNews from years back about

two

Quoted message said:

Quoted message said:

Quoted message said:

guys who claimed they could predict TT times based on the riders' wattage output and their
aero drag. Whatever happened to those guys?

Maybe these guys? www.pkracing.com (I hope that URL is correct.)

Actually I remembered it as being you and Jim Martin. Guess not.

Jim, John Cobb, Kevin McFadden (wind tunnel guru for GM), Doug Milliken (race car suspension genius,
HPV expert, and Moulton aficianado) and I collaborated on a scientific study that was published in
J. Appl. Biomech. However, to the best of my knowledge that didn't result in a lay article in
VeloNews (unless perhaps Jim wrote one, and didn't mention it to me).

Quoted message said:

Quoted message said:

Quoted message said:

Last night I did a little test on a perfectly flat road, 26.5 mph, 1 minute, back and forth
once each. There was a very slight wind and my efa numbers according to his calculations were
.75 and .90 (tailwind and headwind).

You *really* need to subscribe to the wattage list...

I've been lurking off the Topica website but I have to wade through alot of talk about
hardware issues and time trialing-neither of which interest me that much. There are some
pearls there though.

Quoted message said:

Bottom line: while *very careful* field testing can yield fairly precise numbers for CdA (i.e.,
coefficient of variation of ~2%), it still really isn't good enough to be of much use (e.g., for
choosing equipment, or

even

Quoted message said:

Quoted message said:

optimizing position).

Quoted message said:

I was just trying to get a ballpark for my frontal area and to compare my Polar power readings
with his caluclations.

Ack - Polar?? ;-)

Quoted message said:

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That's why I'm going back to the wind tunnel this winter...anybody want to join me?

Quoted message said:

Curious, what does that cost?

Depends on who you are/who you know...but as I recently told somebody else, you might end spending
as much on travel, food, lodging as on actual tunnel time.

Andy Coggan

"Mark Fennell" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

"Kurgan Gringioni" <[email hidden]> wrote in

message news:<[email hidden]>...

Quoted message said:

Quoted message said:

Thanks, but no thanks (and no offense intended). I have one lasting memory of that team and year
that I will take to my grave.

<snip>

It's something to do with that, but not really negative. That was a bad day and ya, none of us will
forget it.

In article <[email hidden]>, Andy Coggan

Quoted message said:

"warren" <[email hidden]> wrote in message

Quoted message said:

Quoted message said:

I was just trying to get a ballpark for my frontal area and to compare my Polar power readings
with his caluclations.

Ack - Polar?? ;-)

Hindsight? The numbers are within 5% of what was measured during the lab tests and they seem to be
consistent across a range and coincide with calculations at analytic cycliing-assuming my frontal
area estimate is fairly close. I got the HRM first and when it was time to add the power sensor the
only reasonable option was to buy the Polar power sensor. The best thing about that was buying it
from Performance Bike because after 13 months with it I'm now on my third power sensor unit and
Performance just asks me if I want a refund or a replacement. After the next one I think it will be
"refund please" so I can buy the SRM.

-WG

FWIW, the contents of this post do not necessarily reflect the opinions or thoughts of anyone other
than myself (and that goes for anything you see me write in any medium at anytime in the future or
in the past) - if you can't figure that one out, then, well, I reckon I can't be held responsible
for how you perceive my commentary.

I've done a bit on the whole cheap-ass aerodynamicist/garage science front. I am not nearly as smart
as Dr. Coggan, Dr. Chester Kyle, nor do I have the cycling specific wind tunnel time of others in
the bike related industry (though, I have more than your average "joe"😉, but I think people can
objectively take a look at their position/frontal area for a small investment of their time (yes, I
realize that a wind tunnel is more than likely the best way to definitively answer the "what
position is best for _me_?" question, but not everyone can afford/wants to go to Texas in the
winter, and the "right" methodology once you are there is still debatable!). Field testing may be
able to produce reliable results, but, IMHO, the time investment necessary to produce a statiscally
significant conclusion is prohibitive for a large scale variable study - i.e, I can generate 100+
statistically significant datasets in a tunnel in one day - try doing that with a field test...

I have documented some of my experiences (yes, the following links are "free" to view) with
mathematical modelling, rider position/frontal area determination and whatnot on my website.

of particular interest are the comparative frontal area results (where my body measures did not
change, but my frontal area certainly did!): - forgive the wordwrap - its either this, or get flamed
for using tinyurl.com - so live with it...

biketechreview.comkw.htmOpen ↗

a comparison between me and someone "important":

biketechreview.comcomparison.htmOpen ↗

My freakishness has even been tolerated by a certain professional cycling team:

biketechreview.comanimations.htmOpen ↗

and concurrently documented by velonews.com:

users.adelphia.netvn.gifOpen ↗

an analysis of the fitchburg TT and what type of power pacing strategy could be most appropriate:

biketechreview.comFitchburg.htmOpen ↗

an analysis of the Redlands Rubidoux prologue TT and equipment selection (the article titled:

6/5/2002 - Is Time-Trial Equipment Selection "Significant"😉 on the page at:

biketechreview.combikecomlinks.htmOpen ↗

I am still developing my methodology for determining frontal area, so for a limited time (say, the
first 5 people that email me offline) I would be willing to document their frontal area for free if
they agree to execute the procedure according to a certain protocol and provide certain body
dimensions (heh, I wrote "body dimension"😉.

Enjoy,

--
==================
Kraig Willett www.biketechreview.com
==================

Andy Coggan said:

"Robert Chung" <[email hidden]> wrote in message

Quoted message said:

Quoted message said:

So if CdA varies with m^0.33, then a 25% difference in mass gives a 7.5% difference in CdA?

Quoted message said:

I know that's a rhetorical question, but the answer is yes: all else (e.g., height, position)
being equal, a 25% increase in mass theoretically results in only a 7.5% difference in CdA. I
believe that makes sense if you think about it...for example, if I gained 37.5 lbs I'd be a true
masters fattie, but I wouldn't be *that* much wider or higher (assuming I could still get down on
the aerobars w/ a big belly in the way).

You guys probably know this, but you're talking about two different relationships. One is a relation
between CdA and mass across a population (all riders, elites, fatties, whatever). I assume this is
what was measured in the article. The other is the relation between CdA and mass for a given rider.
The two relations do not have to have the same log slope. If the population is not representative
there can be a strong bias - for example suppose it was all fairly fit trained riders. Then
Coggan*1.0 would probably fall somewhere near the relation (or below, given his low position) but
Coggan*1.25 wouldn't necessarily, esp. since there was nobody that belly-enhanced in the sample
population.

This is just like the early history of the 220-age HR "rule," BTW - IIRC it was originally derived
from a single relatively unusual population, not a longitudinal study, and not intended for the
abuses to which it has been put.

-Ben Gah! Selection effects!

Benjamin Weiner said:

You guys probably know this, but you're talking about two different relationships. One is a
relation between CdA and mass across a population (all riders, elites, fatties, whatever). I
assume this is what was measured in the article. The other is the relation between CdA and mass
for a given rider.

Right, I hadn't forgotten that. This subthread started off because I think that W is a slightly
better predictor of TT times across riders, while Andy thinks that W/kg is. The calculation above
shows that CdA is relatively inelastic wrt mass.

Quoted message said:

This is just like the early history of the 220-age HR "rule," BTW - IIRC it was originally derived
from a single relatively unusual population, not a longitudinal study, and not intended for the
abuses to which it has been put.

-Ben Gah! Selection effects!

google.comgroupsOpen ↗

I love that story. A non-negligible proportion of my own research findings have been made in
airplanes while on the way to meetings.

"Benjamin Weiner" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Andy Coggan said:

"Robert Chung" <[email hidden]> wrote in message

Quoted message said:

Quoted message said:

So if CdA varies with m^0.33, then a 25% difference in mass gives a

7.5%

Quoted message said:

Quoted message said:

Quoted message said:

difference in CdA?

Quoted message said:

I know that's a rhetorical question, but the answer is yes: all else

(e.g.,

Quoted message said:

Quoted message said:

height, position) being equal, a 25% increase in mass theoretically

results

Quoted message said:

Quoted message said:

in only a 7.5% difference in CdA. I believe that makes sense if you

think

Quoted message said:

Quoted message said:

about it...for example, if I gained 37.5 lbs I'd be a true masters

fattie,

Quoted message said:

Quoted message said:

but I wouldn't be *that* much wider or higher (assuming I could still

get

Quoted message said:

Quoted message said:

down on the aerobars w/ a big belly in the way).

You guys probably know this, but you're talking about two different relationships.

Actually, we're not (see below).

Quoted message said:

One is a relation between CdA and mass across a population (all riders, elites, fatties,
whatever). I assume this is what was measured in the article. The other is the relation between
CdA and mass for a given rider.

I believe (or at least assume) that Robert is talking about the same thing I am, which is the
relationship in a population. I only tossed in the comment about what would happen in an individual
case as an example for those unfamiliar with allometric scaling.

Andy Coggan

"Kraig Willett" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

FWIW, the contents of this post do not necessarily reflect the opinions or thoughts of anyone
other than myself (and that goes for anything you see

me

Quoted message said:

write in any medium at anytime in the future or in the past) - if you

can't

Quoted message said:

figure that one out, then, well, I reckon I can't be held responsible for how you perceive my
commentary.

I've done a bit on the whole cheap-ass aerodynamicist/garage science

front.

Quoted message said:

I am not nearly as smart as Dr. Coggan, Dr. Chester Kyle, nor do I have

the

Quoted message said:

cycling specific wind tunnel time of others in the bike related industry (though, I have more
than your average "joe"😉, but I think people can objectively take a look at their
position/frontal area for a small investment of their time (yes, I realize that a wind tunnel is
more than likely the best way to definitively answer the "what position is best for _me_?"
question, but not everyone can afford/wants to go to Texas in the winter, and the "right"
methodology once you are there is still

debatable!).

<snip>

It seems to me that the windless hill is still the best test although it does have a whiff of
Fredliness to it.

Quoted message said:

I am still developing my methodology for determining frontal area, so for a limited time (say, the
first 5 people that email me offline)

I'd be surprised if you got very many to reply. Aerodynamics is such a non-tactile, nebulous concept
that almost all racers ignore their position once they get one that sort of feels acceptable.

It's sort of amazing to me that people don't pay attention to it. They'll spend $1000 to lose 2 lbs.
from their bike, but that's only ~1% gain vs. the effects of gravity and less than that when one
takes friction and wind resistance into account.

On a flat TT course, OTOH, it's possible to make double digit gains, 10-20%. Yet almost everyone
ignores it.

How many other people in this country pay a lot of attention to aerodynamics in the racing scene?
You. John Cobb. who else?

Kurgan Gringioni said:

I'd be surprised if you got very many to reply. Aerodynamics is such a non-tactile, nebulous
concept that almost all racers ignore their position once they get one that sort of feels
acceptable.

Quoted message said:

It's sort of amazing to me that people don't pay attention to it. They'll spend $1000 to lose 2
lbs. from their bike, but that's only ~1% gain vs. the effects of gravity and less than that when
one takes friction and wind resistance into account.

Even among physicists there is a tendency to stick to things that are easily quantifiable - the
desire to stick with an equation that makes things easy to calculate, even if it's not really right.
So it doesn't really surprise me that Joe Bikeracer behaves the same way - weights are all given in
catalogs, but aero benefits of position or equipment are harder to quantify.

Also, as you have alluded to, it's easier to do things that just involve spending money, like
shaving weight or getting more aero by buying Zipps. Lots of people have Zipps, I dunno how many
have thought about their positioning. Trigeeks think about aero all the time, but have they worked
on their position beyond reading John Cobb articles?

BTW, fluid dynamics is enough of a nonlinear pain in the ass that most physicists are scared
of it too.

Quoted message said:

On a flat TT course, OTOH, it's possible to make double digit gains, 10-20%. Yet almost everyone
ignores it.

Quoted message said:

How many other people in this country pay a lot of attention to aerodynamics in the racing scene?
You. John Cobb. who else?

OTOH, I'm not sure what Kraig is proposing to do. I'm not one to talk, as I am too lazy to even put
on my clip-on aerobars, because I don't feel like redoing the bar tape (however I only do club TTs).
My major investment in this is doing crunches every morning so that I can ride in the drops with
comfort. I think it helps, but who knows.

"Benjamin Weiner" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

BTW, fluid dynamics is enough of a nonlinear pain in the ass that most physicists are scared
of it too.

As well they should be. I'm not talking about doing endless cascading partial differential equations
though. The real world Fred comparison test on the windless hill is what I advocate.

In most cases, eyeballing will help. If a rider's torso is a big air scoop, the fix is obvious.

Quoted message said:

Quoted message said:

On a flat TT course, OTOH, it's possible to make double digit gains,

10-20%.

Quoted message said:

Quoted message said:

Yet almost everyone ignores it.

Quoted message said:

How many other people in this country pay a lot of attention to

aerodynamics

Quoted message said:

Quoted message said:

in the racing scene? You. John Cobb. who else?

OTOH, I'm not sure what Kraig is proposing to do. I'm not one to talk, as I am too lazy to even
put on my clip-on aerobars, because I don't feel like redoing the bar tape (however I only do club
TTs). My major investment in this is doing crunches every morning so that I can ride in the drops
with comfort. I think it helps, but who knows.

That would help in the TT position too as long as you go through a full range of motion.

From what I've seen, the ones who are able to get into extremely aero positions have very good
hamstring and lower back flexibility, which allows them to get low with the flat back and still make
power. If the hamstrings and lower back are short, then the rider has to sit more upright, with the
obvious consequences with respect to the amount of air they're going to catch.

"Andy Coggan" <[email hidden]> wrote in

Quoted message said:

Jim, John Cobb, Kevin McFadden (wind tunnel guru for GM), Doug Milliken (race car suspension
genius, HPV expert, and Moulton aficianado) and I collaborated on a scientific study that was
published in J. Appl. Biomech. However, to the best of my knowledge that didn't result in a
lay article

in

Quoted message said:

VeloNews (unless perhaps Jim wrote one, and didn't mention it to me).

Wasn't me.

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