View Single Post
  #5  
Old October 29th 03, 07:48 PM
Nick Burns
external usenet poster
 
Posts: n/a
Default Armstrong's Tour De France Time Trials

Rik O'Shea wrote:
Armstrong's Tour De France Time Trials

Most people who race or follow cycling know that it is effectively a
sport in which one's performance is governed to a large extent by ones
power output. A good sprinter is defined by someone with a high
top-end power output, a good climber by a high power to weight ratio
and a time trialist by their power output at aerobic threshold. Of
course there are other factors that come into play but power tends to
be the key overriding factor.



What a mess.


With this in mind I've put together some information relating to Lance
Armstrong and his TdF Time Trial performances. Like most people I am
fascinated by his progression especially the pre-post cancer
difference.


I can hardly wait.


I'd like to assume (maybe unwisely) that this thread/discussion can be
kept somewhat factual/objective and that "redneck" responses can be
kept to a minimum.

Notes:
- A Tour De France generally consists of two individual Time Trials.
In the following sections the first time trial is designated by (Xa)
and the second (Xb).

- In all time trials, competitors used "state of the art" aero
equipment (i.e. time trail bike, disk wheels, aero bars, skin suit,
aero position and so on).


Don't forget that riders in a position to place well on GC will put a lot
more effort in to the ITT because they have to balance GC considerations
with recovery where as those not expected to win the stage or place well on
GC will normally choose a much slower pace since there is nothing to gain
on the day.

- The formula for Drag Force due to air resistance can be found at
the end of this article.

------------------------------------0-------------------------------------

----

(1a) 1993 Stage 9 LAC DE MADINE, 59 km ITT
1. Miguel Indurain en 1h12'50" (Moy : 48.604 km/h)
27. Armstrong à 6'04" (Moy : 44.87 km/h)

Comment: Assuming Armstrong has a power output of 420W at aerobic
threshold (this can be regarded as the standard for the average sized
person with a velocity of 45 km/h) he would have to increase his power
output at aerobic threshold by 114W to 534W to match Indurain (this
assumes no change in drag coefficient and frontal area of body).

Note: that even if the baseline value of 420W is disputed (or even
changed - increased/decreased) this still will not affect % increase
in power required in order matching the winner's (in this case
Indurain's) performance.

(1b) 1993 Stage 19 BRETIGNY SUR ORGE-MONTHLERY, 48 km ITT
N/A Armstrong abandoned before TT in line with his Tour plans.

(2a) 1994 Stage 9 PERIGUEUX-BERGERAC, 64 km ITT
1. Miguel Indurain en 1h15'58" (Moy: 50.548 km/h)
13. Armstrong à 6'23" (Moy : 46.63 km/h)

Comment: Assuming Armstrong has a power output of 420W at aerobic
threshold he would have to increase his power output at aerobic
threshold by 115W to 535W to match Indurain (this assumes no change in
drag coefficient and frontal area of body).

(2b) 1994 Stage 19 Cluses-Morzine Avoriaz, 47.5 km ITT
N/A Armstrong abandoned

(3a) 1995 Stage 8 HUY (Bel)-SERAING (Bel), 54 km ITT
1. Miguel Indurain en 1h04'16" (Moy : 50.414 km/h)
19. Armstrong à 5'09" (Moy : 46.67 km/h)

Comment: Assuming Armstrong has a power output of 420W at aerobic
threshold he would have to increase his power output at aerobic
threshold by 110W to 530W to match Indurain (this assumes no change in
drag coefficient and frontal area of body).

(3b) 1995 Stage 19 LAC DE VASSIVIERE, 46.5 km ITT
1. Miguel Indurain en 57'34" (Moy : 48.465 km/h)
43. Armstrong à 6'24" (Moy : 43.62 km/h)


Comment: He did not expect to win any of these stages and did not expect to
be concerned about GC. He likely was "getting through the day". His times
support that statement.


Comment: Assuming Armstrong has a power output of 420W at aerobic


Based on what?

threshold he would have to increase his power output at aerobic
threshold by 156W to 576W to match Indurain (this assumes no change in
drag coefficient and frontal area of body).


He did spend a lot of time in the wind tunnel in between the stages you are
comparing.

Note: this was the first time Armstrong attempted a second time trial
in the Tour (stage 19) and the likely hood is that he may not have
been as motivated as in the first Tour time trials that he
participated in. Therefore there is a likelihood that he didn't reach
his max aerobic power threshold of 420W - using a more reasonable
power output of 530W for the winner Indurain this leads to a more
reasonable value of 390W for Armstrong.


(4a) 1996 No Time Trial info for this year - Armstrong abandoned on
first mountain stage (stage 6) Croix de la Serra - Van Bon


Summary:
Pre-cancer Average Speed 45.447 km/h with an aerobic threshold of
420W.
Excluding the (3b) time trial the data from the time trials is
remarkably consistent with a consistent time and power deficit between
the winner Indurain and Armstrong for each time trial.

1997-98 No TdF participation due to cancer treatment


(5a) 1999 Stage 8 Metz-Metz, 56.5 km ITT
1. Lance Armstrong en 1h08'36" (Moy : 49.417 km/h)

(5b) 1999 Stage 19 Futuroscope-Futuroscope, 57 km ITT
1. Lance Armstrong en 1h08'17" (Moy : 50.085 km/h)

(6a) 2000 Stage 1 FUTUROSCOPE, 16.5 km ITT
1. David Millar (Gbr) en 19'03" (Moy : 51.968 km/h)
2. Lance Armstrong (Usa) à 2" (Moy : 51.361 km/h)

(6b) 2000 Stage 19 FRIBOURG EN BRISGAU (All)-MULHOUSE, 58.5 km
1. Lance Armstrong (Usa) en 1h05'01" (Moy : 53.986 km/h)

(7a) 2001 Stage 11 Grenoble-Chamrousse, 32 km ITT
1. Lance Armstrong (Usa) en 1h07'27" (Moy : 28.466 km/h) * Mountain
TT not used in calculation of average

(7b) 2001 Stage 18 MONTLUCON-SAINT AMAND MONTROND, 61 km ITT
1. Lance Armstrong (Usa) en 1h14'16" (Moy : 49,282 km/h)

(8a) 2002 Stage 9 Lanester-Lorient, 52 km ITT
1. Santiago Botero (Col) en 1h02'19" (Moy : 50.066 km/h)
2. Lance Armstrong (Usa) à 11" (Moy : 49.92 km/h)

(8b) 2002 Stage 19 Régnié Durette-Mâcon, 50 km ITT
1. Lance Armstrong (Usa) en 1h03'50" (Moy : 46.997 km/h)

(9a) 2003 Stage 12 Gaillac-Cap Découverte, 47 km ITT
1. Jan Ullrich (All) en 58'32" (Moy : 48.178 km/h)
2. Lance Armstrong (Usa) à 1'36" (Moy : 46.896 km/h)

(9b) 2003 Stage 19 Pornic-Nantes, 49 km ITT
1. David Millar (Gbr) en 54'05" (Moy : 54.361 km/h)
2. Tyler Hamilton (Usa) à 9"
3. Lance Armstrong (Usa) à 14" (Moy : 54.123 km/h)


Summary:
Post Cancer Average Speed 50.229 km/h

Difference pre-post cancer (50.229 - 45.447) = 4.782 km/h

Assuming Armstrong had a pre cancer power output of 420W at aerobic
threshold


You have no idea how close to his threshold he raced.

he would have to increase this by 147W to 567W to achieve
this increase in speed. This represents a remarkable increase in
aerobic power in an already highly trained professional athlete.


Or some combination of racing closer to his power limits, increasing his
power limits and decreasing air resistance.

So, he gained nothing from all of those expesive TT frames, that one of a
kind (for a while) TT helmet, and changes in position?

I do not think so


Factors that can help increase velocity at a given a given power
output:

"Hyper motivated" - being "hyper motivated" will not increase the
physically defined limit of power at aerobic threshold.


No. It means that instead of racing at 90% of his max, he raced closer to 98
or 99%.

That is the difference between pack filler and a contender for stage or GC
win.

It will not
increase it but it will allow you to reach or approach your limit. For
example if your physical limit is 420W then due to lack of motivation


Then it was not a max value, now was it?

factors you may only produce 380W or 390W in a time trial but being


Or race at 420 watts average over the course and have a lot more available
power..

extremely motivated may allow you to reach 420W (you will not exceed
the physical limit in a "long" time trial - shorter time trails such
as a individual pursuit or prologue allow one to use anaerobic power
for a short duration).


It sounds like in order to make your case, one needs special knowledge that
you have about which stages represent maximum power and which do not.


"Reduced weight" - if you lost 10 lbs (about 5%), you would typical
only increase you time in "flat" time trials by about 0.4% however you
would go faster (4-5%) uphill.


He lost so much weight that it lowered his drag! He lost about 20 pounds of
muscle in his upper body.


"Reduced drag" - this is where the biggest advantage can be obtained.
However the potential increase assumes that you have not already taken
advantage of the "state of the art" elements at your disposal (i.e.
that you do not already use aero time trail position, time trail bike,
disk wheels, aero bars, skin suit and so on).


Right, which he had not.


------------------------------------0-------------------------------------

Formula Drag Force due to air resistance:

Fdrag = Cdrag V*V A

whe
Cdrag = drag coefficient (a function of the shape of the body and
the density of the fluid)
A = frontal area of body
V = velocity

Since: Power = Force x Velocity

i.e. to double your speed requires 8 times as much power just to
overcome air drag (since power ~ velocity3)


How many of those variables can you solve? You only have "V". Is that enough
to solve any other variables? You seem to imply you can, so why not solve
them?


------------------------------------0-------------------------------------

Thanks & regards
-R



That was kind of a waste of time. A lot more information is required to
learn anything specific. All we have are plenty of variables to guess about.


Ads
 

Home - Home - Home - Home - Home