Power Profiling -- good stuff
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In another thread, Andy Coggan pointed toward his article "Power Profiling" at www.cyclingpeaks.com
containing an Excel table of W/kg for different duration efforts and a range of performance levels
going from world champions down to untrained athletes. IMHO, this is really good stuff for anyone
who wants to be at all analytical or objective about his/her training and performance. That said, I
have a number of questions and comments for Andy or any other of the power gurus and advocates.
(Warning: this may turn out to be a long post so either move on now, or go read his article if you
haven't already.)
First, it seems like the way you bracketed the groups is natural, and in my admittedly subjective
experience and observation, the overlap is reasonable. By that I mean, for example, the "lower half"
of the cat 1's is comparable to the "upper half" of the 2's, etc., at least to first order. I'm
curious how confident you are in the values in the table between "World Champ" and "Untrained". I
ask for two reasons. For one, my own profile doesn't fit the way I would expect. And second, the
values in the table progress linearly (as you move through ability levels) and the brackets cover a
constant, wide range. As we all know, assume a relationship is linear if we don't have enough data
or insights that say it should be otherwise!
In particular, I'm wondering if you might be a little bit low with the "5 min" and "20 min" W/kg
values, at least in the Div. III pro through cat 3 range, and perhaps a little high for the "5 s"
and "1 min" values. For example, I am pretty confident that the best cat 1 climbers can put out more
than 5.19 W/kg over a 20-minute effort.
My own profile, at age 42, is as follows:
Duration: W/kg:
----------------------
20 minute: 4.7 5 minute: 5.1 1 minute: 8.1 5 second: 13-15
My values were about 10% higher when I last raced seriously, about 12 years ago. I did win a couple
of P12 road races then, but I was certainly not at the level that the table indicates for the
20-minute level. OTOH, I'm pretty sure I could sprint better than the average cat 4, which is where
the table puts me for the 5-second test.
BTW, please don't think I'm nit-picking the article and the table. I think the information is great
and really useful. I just think you might like hearing about some other data points!
Another question or two...
It would be fascinating to see some real profiles for a variety of ability levels and specialties
(and all-arounders). Does anyone have some profiles they can share? My profile shows decent lactate
tolerance and VO2Max but pretty weak short-term power. I'm curious, is there really anyone that is
well-trained and has a flat profile?
Also, W/kg is clearly a good indicator of climbing performance. But for time trialing, it isn't that
strongly related is it? In my case, my 20-minute W/kg suggest I should be in the cat 1-2 range which
I think is reasonable for climbing, but, trust me, it's way off for time trialing. In your
experience, should someone be able to work on their aero position, etc. so that their climbing and
tt'ing are comparable, at least relative to other riders in the same category? In other words, is
body mass a good indicator for the aerodynamic drag one should be able to achieve? I wouldn't think
so, but the power-profile article and table sort of suggest that one's climbing and tt'ing can be
similarly categorized based on mass alone.
Anyway, thanks again for sharing your great information and insights.
Mark Fennell
It would seem a bit more useful if there was some sort of correlation between poewr output and some
other measurement such as TT speed.
"Mark Fennell" <marco_fennelli@yahoo.com> wrote in message
news:705a928b.0308181744.3024df0@posting.google.com...
> In another thread, Andy Coggan pointed toward his article "Power Profiling" at
> www.cyclingpeaks.com containing an Excel table of W/kg for different duration efforts and a range
> of performance levels
going
> from world champions down to untrained athletes. IMHO, this is
really
> good stuff for anyone who wants to be at all analytical or objective about his/her training and
> performance. That said, I have a number
of
> questions and comments for Andy or any other of the power gurus and advocates. (Warning: this may
> turn out to be a long post so either move on now, or go read his article if you haven't already.)
>
> First, it seems like the way you bracketed the groups is natural,
and
> in my admittedly subjective experience and observation, the overlap
is
> reasonable. By that I mean, for example, the "lower half" of the cat 1's is comparable to the
> "upper half" of the 2's, etc., at least to first order. I'm curious how confident you are in the
> values in the table between "World Champ" and "Untrained". I ask for two reasons. For one, my own
> profile doesn't fit the way I would expect. And second, the values in the table progress linearly
> (as you move
through
> ability levels) and the brackets cover a constant, wide range. As we all know, assume a
> relationship is linear if we don't have enough
data
> or insights that say it should be otherwise!
>
> In particular, I'm wondering if you might be a little bit low with
the
> "5 min" and "20 min" W/kg values, at least in the Div. III pro
through
> cat 3 range, and perhaps a little high for the "5 s" and "1 min" values. For example, I am pretty
> confident that the best cat 1 climbers can put out more than 5.19 W/kg over a 20-minute effort.
>
> My own profile, at age 42, is as follows:
>
> Duration: W/kg:
> ----------------------
> 20 minute: 4.7 5 minute: 5.1 1 minute: 8.1 5 second: 13-15
>
> My values were about 10% higher when I last raced seriously, about
12
> years ago. I did win a couple of P12 road races then, but I was certainly not at the level that
> the table indicates for the
20-minute
> level. OTOH, I'm pretty sure I could sprint better than the average cat 4, which is where the
> table puts me for the 5-second test.
>
> BTW, please don't think I'm nit-picking the article and the table. I think the information is
> great and really useful. I just think you might like hearing about some other data points!
>
> Another question or two...
>
> It would be fascinating to see some real profiles for a variety of ability levels and specialties
> (and all-arounders). Does anyone have some profiles they can share? My profile shows decent
> lactate tolerance and VO2Max but pretty weak short-term power. I'm curious,
is
> there really anyone that is well-trained and has a flat profile?
>
> Also, W/kg is clearly a good indicator of climbing performance. But for time trialing, it isn't
> that strongly related is it? In my case, my 20-minute W/kg suggest I should be in the cat 1-2
> range which I think is reasonable for climbing, but, trust me, it's way off for
time
> trialing. In your experience, should someone be able to work on
their
> aero position, etc. so that their climbing and tt'ing are
comparable,
> at least relative to other riders in the same category? In other words, is body mass a good
> indicator for the aerodynamic drag one should be able to achieve? I wouldn't think so, but the
power-profile
> article and table sort of suggest that one's climbing and tt'ing can be similarly categorized
> based on mass alone.
>
> Anyway, thanks again for sharing your great information and
insights.
>
> Mark Fennell
In article <LIf0b.429$Ls2.84@newsread4.news.pas.earthlink.net>, Tom Kunich
<tkunich@earthlink.net> wrote:
> It would seem a bit more useful if there was some sort of correlation between poewr output and
> some other measurement such as TT speed.
But TT speed has only two variables (other than wind, road surface, hills), power output for the
time period, and aerodynamic drag. Aero drag should be closely related to rider weight/size so if
you know weight and power somebody like Andy could reasonably calculate your TT time and shoe size.
-WG
warren wrote:
> In article <LIf0b.429$Ls2.84@newsread4.news.pas.earthlink.net>, Tom Kunich
> <tkunich@earthlink.net> wrote:
>
>> It would seem a bit more useful if there was some sort of correlation between poewr output and
>> some other measurement such as TT speed.
>
> But TT speed has only two variables (other than wind, road surface, hills), power output for
> the time period, and aerodynamic drag. Aero drag should be closely related to rider weight/size
> so if you know weight and power somebody like Andy could reasonably calculate your TT time and
> shoe size.
Not quite. The "A" part of CdA varies roughly with the 2/3 power of mass, but the "Cd" part doesn't.
Because of the way these things scale, W/kg is a good indicator of climbing ability, but total W is
a good indicator of TT ability.
Mark Fennell wrote:
>
> ... IMHO, this is really good stuff for anyone who wants to be at all analytical or objective
> about his/her training and performance....
Finally. A thread where Chang will have nothing to contribute.
"Mark Fennell" <marco_fennelli@yahoo.com> wrote in message
news:705a928b.0308181744.3024df0@posting.google.com...
>
> It would be fascinating to see some real profiles for a variety of ability levels and specialties
> (and all-arounders). Does anyone have some profiles they can share? My profile shows decent
> lactate tolerance and VO2Max but pretty weak short-term power. I'm curious, is there really anyone
> that is well-trained and has a flat profile?
>
> Also, W/kg is clearly a good indicator of climbing performance. But for time trialing, it isn't
> that strongly related is it? In my case, my 20-minute W/kg suggest I should be in the cat 1-2
> range which I think is reasonable for climbing, but, trust me, it's way off for time trialing. In
> your experience, should someone be able to work on their aero position, etc. so that their
> climbing and tt'ing are comparable, at least relative to other riders in the same category?
If you work on your aero position, you should be able to get much better than riders in
your category.
The reason is that getting more aero is not easy to quantify, unless one has access to a wind
tunnel. People will spend $5 per gram shaving weight off their bike, yet not spend any time at all
improving their time trial position, where the relative benefits are much higher.
IIRC, if the drag coefficient for riding on the hoods is 100, then getting in the drops is ~80% of
that, getting a full aero setup is ~65-70%, etc. Riders like Colby Pearce or Chris Boardman could
get down to ~50% or lower.
The proportional savings are far greater than shaving a pound or two off your bike, especially when
one considers that the weight of the rider must be factored into the proportional savings of the
system as a whole.
>In other words, is body mass a good indicator for the aerodynamic drag one should be able to
>achieve? I wouldn't think so,
You are correct, body mass is not a good indicator.
>but the power-profile article and table sort of suggest that one's climbing and tt'ing can be
>similarly categorized based on mass alone.
That may be true if one generalizes, but in specific cases (like Boardman or Pearce) it is not true.
My last year racing, I went ahead and worked on the TT position after ignoring it for 10 years. I
was still pretty crappy at it, but I could tell the value it had by taking it out on group rides.
It's pretty amazing what a difference it makes. If I were to ever race again, I'd spend a lot of
time trying to get more aero with a normal road setup.
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 the handlebar in breakaways, even through turns? He
had that figured out.
In article <3F419AB9.F2E9CFCB@ti.com>, gwhite <gwhite@ti.com> wrote:
> Mark Fennell wrote:
> >
>
> > ... IMHO, this is really good stuff for anyone who wants to be at all analytical or objective
> > about his/her training and performance....
>
> Finally. A thread where Chang will have nothing to contribute.
So what else is new?
-WG
warren wrote:
>
> In article <3F419AB9.F2E9CFCB@ti.com>, gwhite <gwhite@ti.com> wrote:
>
> > Mark Fennell wrote:
> > >
> >
> > > ... IMHO, this is really good stuff for anyone who wants to be at all analytical or objective
> > > about his/her training and performance....
> >
> > Finally. A thread where Chang will have nothing to contribute.
>
> So what else is new?
Nada. Stick a fork in me, I'm done.
"Mark Fennell" <marco_fennelli@yahoo.com> wrote in message
news:705a928b.0308181744.3024df0@posting.google.com...
>
> In particular, I'm wondering if you might be a little bit low with the "5 min" and "20 min" W/kg
> values, at least in the Div. III pro through cat 3 range, and perhaps a little high for the "5 s"
> and "1 min" values. For example, I am pretty confident that the best cat 1 climbers can put out
> more than 5.19 W/kg over a 20-minute effort.
>
Hmm - my best sprint peak power (I don't know about holding it for 5s) is about 5 "vertical squares"
below that of my 20 min value. But I always knew I couldn't sprint :-). Wish it wasn't so critical.
Jeff
On 18 Aug 2003 18:44:32 -0700, Mark Fennell wrote:
>It would be fascinating to see some real profiles for a variety of ability levels and specialties
>(and all-arounders).
Check the rowing world, they've been doing it for years. They do tests on the Concept2 rowing
machine, and, ideally, the power output should be distributed thus:
Test Hwt men Lwt women 10" 123% 118% 1' 115% 112% 2 km 100% 100% 6 km 93% 95% 1 h ? 90%
(The numbers for Lwt men and hwt women are in between these. For hwt men, 2k takes about 6' and 6k
about 19'30". Lwt women 7'15" and 23'00". "Heavyweight" really means "open class"; typically those
men are 1m95 and 90 kg. Lightweight women cannot weigh more than 59 kg and are around 1m70.)
In rowing, the goal is always to deliver a maximum performance on 2 km, that's why that score is a
reference at 100%. If some of your percentages fall behind, you should spend (extra) time training
that particular zone. Ultimately, that will benefit the 2k score.
"Robert Chung" <invalid@nospam.com> wrote in message news:3f41987d$0$1147$626a54ce@news.free.fr...
> warren wrote:
> > In article <LIf0b.429$Ls2.84@newsread4.news.pas.earthlink.net>, Tom Kunich
> > <tkunich@earthlink.net> wrote:
> >
> >> It would seem a bit more useful if there was some sort of correlation between poewr output and
> >> some other measurement such as TT speed.
> >
> > But TT speed has only two variables (other than wind, road surface, hills), power output for
> > the time period, and aerodynamic drag. Aero drag should be closely related to rider weight/size
> > so if you know weight and power somebody like Andy could reasonably calculate your TT time and
> > shoe size.
>
> Not quite. The "A" part of CdA varies roughly with the 2/3 power of mass, but the "Cd" part
> doesn't. Because of the way these things scale, W/kg is a good indicator of climbing ability, but
> total W is a good indicator of TT ability.
Except that Heil et al. have concluded that Cd also varies inversely with weight (with an exponent
of -0.45). The overall result is then as Warren indicates, i.e., even though mass per se has little
effect on the power requirement to travel at a fixed velocity on a completely flat road, W/kg is
still likely to be a better predictor of TT performance than W alone.
Andy Coggan
"Mark Fennell" <marco_fennelli@yahoo.com> wrote in message
news:705a928b.0308181744.3024df0@posting.google.com...
> In another thread, Andy Coggan pointed toward his article "Power Profiling" at
> www.cyclingpeaks.com containing an Excel table of W/kg for different duration efforts and a range
> of performance levels going from world champions down to untrained athletes. IMHO, this is really
> good stuff for anyone who wants to be at all analytical or objective about his/her training and
> performance. That said, I have a number of questions and comments for Andy or any other of the
> power gurus and advocates. (Warning: this may turn out to be a long post so either move on now, or
> go read his article if you haven't already.)
>
> First, it seems like the way you bracketed the groups is natural, and in my admittedly subjective
> experience and observation, the overlap is reasonable. By that I mean, for example, the "lower
> half" of the cat 1's is comparable to the "upper half" of the 2's, etc., at least to first order.
> I'm curious how confident you are in the values in the table between "World Champ" and
> "Untrained". I ask for two reasons. For one, my own profile doesn't fit the way I would expect.
> And second, the values in the table progress linearly (as you move through ability levels) and the
> brackets cover a constant, wide range. As we all know, assume a relationship is linear if we don't
> have enough data or insights that say it should be otherwise!
As the accompanying article indicates, I fixed the upper and lower ends of each range based on known
power outputs of world champions/world record holders and untrained individuals, respectively. The
values in between were spread equally (i.e., linear relationship assumed), simply because at present
there's not enough data to justify doing otherwise. Remember, the purpose of the tables is to
compare relative ability across different exercise durations reflecting different physiological
characteristics, not to attempt to assign or describe riders of different categories (strip the
category guidelines from the tables, and they would be just as useful). This is why I didn't assume
a normal distribution and spread the values that way - that might (or might not - no one at present
has the data to say for sure) better reflect reality, but has the disadvantage of squeezing
everything together toward the middle, making anyone who isn't well above or well below average
appear to be an "all rounder".
> In particular, I'm wondering if you might be a little bit low with the "5 min" and "20 min" W/kg
> values, at least in the Div. III pro through cat 3 range, and perhaps a little high for the "5 s"
> and "1 min" values. For example, I am pretty confident that the best cat 1 climbers can put out
> more than 5.19 W/kg over a 20-minute effort.
>
> My own profile, at age 42, is as follows:
>
> Duration: W/kg:
> ----------------------
> 20 minute: 4.7 5 minute: 5.1 1 minute: 8.1 5 second: 13-15
>
> My values were about 10% higher when I last raced seriously, about 12 years ago. I did win a
> couple of P12 road races then, but I was certainly not at the level that the table indicates for
> the 20-minute level. OTOH, I'm pretty sure I could sprint better than the average cat 4, which is
> where the table puts me for the 5-second test.
Better than the average cat 4 *match sprinter*, as that notion implies for somebody with that
relative ability to compared to, e.g., Sean Eadie? Again, as described in the accompanying article,
by basing things on the performance of specialists (match sprinters for 5 s), the scales tend to be
skewed from a road racers perspective. To state it another way: compared to a true sprinter, most
people racing on the road *do* have relatively low neuromuscular power. However, I don't think one
really can or should try to develop discipline-specific tables. First, too many people cross over to
different disciplines, thus making it difficult to develop valid standards, esp. since the only
point proposing discipline-specific tables would be to improve the category guidelines - which
aren't the point of the tables in the first place. Second, discipline-specific tables would deviate
from the logic that was used to develop the tables in the first place.
> BTW, please don't think I'm nit-picking the article and the table. I think the information is
> great and really useful. I just think you might like hearing about some other data points!
>
> Another question or two...
>
> It would be fascinating to see some real profiles for a variety of ability levels and specialties
> (and all-arounders). Does anyone have some profiles they can share? My profile shows decent
> lactate tolerance and VO2Max but pretty weak short-term power. I'm curious, is there really anyone
> that is well-trained and has a flat profile?
>
> Also, W/kg is clearly a good indicator of climbing performance. But for time trialing, it isn't
> that strongly related is it? In my case, my 20-minute W/kg suggest I should be in the cat 1-2
> range which I think is reasonable for climbing, but, trust me, it's way off for time trialing. In
> your experience, should someone be able to work on their aero position, etc. so that their
> climbing and tt'ing are comparable, at least relative to other riders in the same category? In
> other words, is body mass a good indicator for the aerodynamic drag one should be able to achieve?
> I wouldn't think so, but the power-profile article and table sort of suggest that one's climbing
> and tt'ing can be similarly categorized based on mass alone.
This has been addressed in other posts...I'll only add the reminder (once again) that the point of
the tables is to help evaluate somebody's relative strengths and weaknesses, not predict their
performance.
> Anyway, thanks again for sharing your great information and insights.
You're welcome.
BTW, there is a ~700 member mailing list at www.topica.com/lists/wattage/read devoted to discussion
of training with power meters, etc....based on the interest you've expressed here, you might want to
give it a read.
Andy Coggan
Andy Coggan wrote:
> "Robert Chung" <invalid@nospam.com> wrote
>> Not quite. The "A" part of CdA varies roughly with the 2/3 power of mass, but the "Cd" part
>> doesn't. Because of the way these things scale, W/kg is a good indicator of climbing ability, but
>> total W is a good indicator of TT ability.
>
> Except that Heil et al. have concluded that Cd also varies inversely with weight (with an exponent
> of -0.45). The overall result is then as Warren indicates, i.e., even though mass per se has
> little effect on the power requirement to travel at a fixed velocity on a completely flat road,
> W/kg is still likely to be a better predictor of TT performance than W alone.
Cd varies inversely with mass? Hmmm, I didn't know that. Anyway, if A varies (roughly) with m^.67
and Cd varies (roughly) with m^(-.45), then CdA would vary roughly with m^(.2). A 25% difference in
mass gives a 2% difference in CdA?
I wrote:
> Andy Coggan wrote:
>> "Robert Chung" <invalid@nospam.com> wrote
>>> Not quite. The "A" part of CdA varies roughly with the 2/3 power of mass, but the "Cd" part
>>> doesn't. Because of the way these things scale, W/kg is a good indicator of climbing ability,
>>> but total W is a good indicator of TT ability.
>>
>> Except that Heil et al. have concluded that Cd also varies inversely with weight (with an
>> exponent of -0.45). The overall result is then as Warren indicates, i.e., even though mass per se
>> has little effect on the power requirement to travel at a fixed velocity on a completely flat
>> road, W/kg is still likely to be a better predictor of TT performance than W alone.
>
> Cd varies inversely with mass? Hmmm, I didn't know that. Anyway, if A varies (roughly) with m^.67
> and Cd varies (roughly) with m^(-.45), then CdA would vary roughly with m^(.2). A 25% difference
> in mass gives a 2% difference in CdA?
Goddammit, I hit the wrong key. Anyway, my calculation was off but the point should still be the
same: A 25% difference in mass gives a 5% difference in CdA?
In article <3f4219d1$0$16160$626a54ce@news.free.fr>, Robert Chung <invalid@nospam.com> wrote:
> I wrote:
> > Andy Coggan wrote:
> >> "Robert Chung" <invalid@nospam.com> wrote
> >>> Not quite. The "A" part of CdA varies roughly with the 2/3 power of mass, but the "Cd" part
> >>> doesn't. Because of the way these things scale, W/kg is a good indicator of climbing ability,
> >>> but total W is a good indicator of TT ability.
> >>
> >> Except that Heil et al. have concluded that Cd also varies inversely with weight (with an
> >> exponent of -0.45). The overall result is then as Warren indicates, i.e., even though mass per
> >> se has little effect on the power requirement to travel at a fixed velocity on a completely
> >> flat road, W/kg is still likely to be a better predictor of TT performance than W alone.
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?
> > Cd varies inversely with mass? Hmmm, I didn't know that. Anyway, if A varies (roughly) with
> > m^.67 and Cd varies (roughly) with m^(-.45), then CdA would vary roughly with m^(.2). A 25%
> > difference in mass gives a 2% difference in CdA?
>
> Goddammit, I hit the wrong key. Anyway, my calculation was off but the point should still be the
> same: A 25% difference in mass gives a 5% difference in CdA?
At Analytic Cycling he uses "effective frontal area" measured in square meters for aero drag. I'm
curious if you can calculate reasonably well this based on rider height and weight. He says typical
values are .4 to .7 m2. 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).
-WG
warren wrote:
>
> 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?
I agree, you can do a good job predicting TT times based on wattage and aero drag; but what you
wrote upthread was that if you know wattage and *weight* someone could predict TT times. Someone
could -- I just think the prediction wouldn't be as good as wattage and aero drag.
> At Analytic Cycling he uses "effective frontal area" measured in square meters for aero drag. I'm
> curious if you can calculate reasonably well this based on rider height and weight. He says
> typical values are .4 to .7 m2. 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).
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. 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).
"Mark Fennell" <marco_fennelli@yahoo.com> wrote in message
news:705a928b.0308190856.237ed648@posting.google.com...
> "Andy Coggan" <acoggan@earthlink.net> wrote in message
news:<sSn0b.701$Ls2.590@newsread4.news.pas.earthlink.net>...
> >
> > As the accompanying article indicates, I fixed the upper and lower ends
of
> > each range based on known power outputs of world champions/world record holders and untrained
> > individuals, respectively. The values in between
were
> > spread equally (i.e., linear relationship assumed), simply because at present there's not enough
> > data to justify doing otherwise. Remember,
the
> > purpose of the tables is to compare relative ability across different exercise durations
> > reflecting different physiological characteristics,
not
> > to attempt to assign or describe riders of different categories (strip
the
> > category guidelines from the tables, and they would be just as useful).
This
> > is why I didn't assume a normal distribution and spread the values that way - that might (or
> > might not - no one at present has the data to say
for
> > sure) better reflect reality, but has the disadvantage of squeezing everything together toward
> > the middle, making anyone who isn't well
above or
> > well below average appear to be an "all rounder".
> >
>
> Fair enough! But it would still be extremely useful to see some actual profiles for a variety of
> types of riders. Otherwise one doesn't really know how alarmed (or satisfied) to be with a "/"
> profile or a "\" or a "^". Or, how much slope matters?
I suppose we could put up some examples on the website.
> Also, I assume the Untrained subjects represented characteristics of the general population and
> were not in any way predisposed to the 5-second or 20-minute abilities.
No reason to think that the values are skewed in any way.
> I wonder what percentage of people have the genetics (or whatever) to excel at the 5-second versus
> the 20-minute performance, if trained. It seems to me, **in theory**, that would impact whether or
> not the columns are linear.
It seems to me that if you assume that there's a big enough population base fighting it out to be
"top dog" in each speciality, then that assures that the scales will align properly (the most
important part). As I indicated before, logically one would expect that each scale should *not* be
linear (thus addressing your point about the extremes), but instead be normally distributed. I
could, for example, have assumed that world champion/world record performance is, say, 5 SDs above
the mean, and the lowest level of the untrained 5 SDs below, or something like that - however, that
doesn't alter the comparison across scales, and has the disadvantage of crowding together all values
in the middle.
To reiterate: the category guidelines accompanying the scales are just rough approximations, i.e.,
most riders of a certain category can generate the specified power for the specified duration -
however, that doesn't mean that all can, nor does it mean that just because you can generate a
certain amount of power that you should be a certain category (although it does indicate that you
have that potential).
One more caveat: from a theoretical perspective, the values should really be
W/kg^0.67, not W/kg...however, I think that such allometric scaling might be a little beyond the
average person's grasp, at least w/o extensive explanation.
Andy Coggan
"Mark Fennell" <marco_fennelli@yahoo.com> wrote in message
news:705a928b.0308190908.57670fce@posting.google.com...
> "Kurgan Gringioni" <kgringioni.remove.it.for.mail@hotmail.com> wrote in
message news:<NFh0b.4015$Nc.2637059@news1.news.adelphia.net>...
> >
> > If you work on your aero position, you should be able to get much better than riders in your
> > category.
> >
> > The reason is that getting more aero is not easy to quantify, unless one
has
> > access to a wind tunnel. People will spend $5 per gram shaving weight
off
> > their bike, yet not spend any time at all improving their time trial position, where the
> > relative benefits are much higher.
> >
>
> I agree with this concept, but I'll never tt anywhere close to guys like Thurlow Rogers or Eric
> Sternlict in SoCal. I'd be pleased to add a mph or two though.
All it takes, like anything else in cycling, is work. Stretching, a lot of it, so that your lower
back and hamstrings are long enough to make power in the low position. One day/week of interval
training in the position. Gradual upgrading of the tt bike on all 1st order components (ones which
break the wind). And constant tweaking of the position, timing differences on a long straight
windless descent (coasting down, poor man's wind tunnel).
> > 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
> > the handlebar in breakaways, even through turns? He had that figured
out.
>
> 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.
The reason I thought you were a Master is because of the Longo Visalia story you related.
"Robert Chung" <invalid@nospam.com> wrote in message news:3f421264$0$16143$626a54ce@news.free.fr...
> Andy Coggan wrote:
> > "Robert Chung" <invalid@nospam.com> wrote
> >> Not quite. The "A" part of CdA varies roughly with the 2/3 power of mass, but the "Cd" part
> >> doesn't. Because of the way these things scale, W/kg is a good indicator of climbing ability,
> >> but total W is a good indicator of TT ability.
> >
> > Except that Heil et al. have concluded that Cd also varies inversely with weight (with an
> > exponent of -0.45). The overall result is then as Warren indicates, i.e., even though mass per
> > se has little effect on the power requirement to travel at a fixed velocity on a completely flat
> > road, W/kg is still likely to be a better predictor of TT performance than W alone.
>
> Cd varies inversely with mass? Hmmm, I didn't know that. Anyway, if A varies (roughly) with m^.67
> and Cd varies (roughly) with m^(-.45), then CdA would vary roughly with m^(.2). A 25% difference
> in mass gives a 2% difference in CdA?
You're the one that said A varies with mass^0.67, not me (remember that we're talking about frontal
area of a rider in the aero position, not simple body surface area. Be that as it may, Heil
concluded that Cd must vary with mass^-0.45 because of experimental observations that CdA varies
with mass^0.33 (or thereabouts). Depending on what other variables were entered into the multiple
regression, A in their study varied with mass^0.408 to mass^0.762....meaning that Cd had to be
inversely related to mass to get the coefficient for mass related to CdA down around one-third.
Andy Coggan
"warren" <warren@usvhremove.com> wrote in message news:190820030823419787%warren@usvhremove.com...
> In article <3f4219d1$0$16160$626a54ce@news.free.fr>, Robert Chung <invalid@nospam.com> wrote:
>
> > I wrote:
> > > Andy Coggan wrote:
> > >> "Robert Chung" <invalid@nospam.com> wrote
> > >>> Not quite. The "A" part of CdA varies roughly with the 2/3 power of mass, but the "Cd" part
> > >>> doesn't. Because of the way these things scale, W/kg is a good indicator of climbing
> > >>> ability, but total W is
a
> > >>> good indicator of TT ability.
> > >>
> > >> Except that Heil et al. have concluded that Cd also varies inversely with weight (with an
> > >> exponent of -0.45). The overall result is then
as
> > >> Warren indicates, i.e., even though mass per se has little effect on the power requirement to
> > >> travel at a fixed velocity on a completely flat road, W/kg is still likely to be a better
> > >> predictor of TT performance than W alone.
>
> 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.)
In any case, prediction of TT times from power and aero drag can be done with tremendous
accuracy...as long as you also know the course profile and wind speed/direction accurately enough.
> > > Cd varies inversely with mass? Hmmm, I didn't know that. Anyway, if A varies (roughly) with
> > > m^.67 and Cd varies (roughly) with m^(-.45),
then
> > > CdA would vary roughly with m^(.2). A 25% difference in mass gives a
2%
> > > difference in CdA?
> >
> > Goddammit, I hit the wrong key. Anyway, my calculation was off but the point should still be the
> > same: A 25% difference in mass gives a 5% difference in CdA?
>
> At Analytic Cycling he uses "effective frontal area" measured in square meters for aero drag. I'm
> curious if you can calculate reasonably well this based on rider height and weight. He says
> typical values are .4 to .7 m2.
FWIW, that's A, not CdA...the numbers are in the right ballpark, maybe a little low. OTOH, the
default value for Cd that Tom uses (i.e., 0.5) is too low, so the product (i.e., 0.25 m^2) is in the
right ballpark.
> 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...
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). That's why I'm going back to the wind tunnel this
winter...anybody want to join me?
Andy Coggan
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