Re: Landis' aerobars

In article <4ek6seF1ek23gU1@xxxxxxxxxxxxxx>,
"Steve Freides" <steve@xxxxxxxxxxxxxxxxxxx> wrote:

"Ryan Cousineau" <rcousine@xxxxxx> wrote in message
news:rcousine-B5631E.18352305062006@xxxxxxxxxxxxxxxxx
In article <4eje17F1eiq2vU1@xxxxxxxxxxxxxx>,
"Steve Freides" <steve@xxxxxxxxxxxxxxxxxxx> wrote:

"jeremy" <jeremy.stitt@xxxxxxxxx> wrote in message
news:1149532331.622331.293990@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Steve Freides wrote:

I don't think this is a one-size-fits-all kind of thing - there
are
tradeoffs wherein a more aero position simply doesn't let you
pedal
or
breath as well and results in an overall deficit in performance.
It
looks like Menchov's back is already flatter than Landis', i.e.,
Menchov's hips are higher in relation to his shoulders than
Landis'.
Looks like Menchov's legs are quite a bit longer than Landis'.

-S-

Interesting comments -

Thank you but this is nothing new.

.so how to those without access to a wind tunnel
decide which position is best for them (besides the odvious Time
Trial
& Error approach)?

To a first order, an amateur can get the "right" TT position by taking
a
picture and using it to measure (and minimize!) their frontal area,
and
then make some educated guesses about the aerodynamics.

I think this is a bit too much of an oversimplication. Look, e.g., at
this picture of Ullrich from earlier this year:

http://www.cyclingnews.com/photos/2006/apr06/romandie06/index.php?id=romandie065/Par734507

He is clearly _not_ going for a small frontal area - he looks a lot like
the Menchov pictures.

This photo raises questions, but perhaps as many for you as for me:

-the caption says Jan is approaching the finish. Was he making a
finishing push, and thus not entirely in his usual tuck?

-where are Jan's hips? Would getting his chest lower result in an
appreciable reduction in frontal area, or just make him less comfortable?

What's most aerodynamic for some may be to focus on total frontal area,
but Jan's positioning suggests different thinking. I don't imagine one
of the world's best time trialists, well, you can finish that sentence
for yourself. :)

I did say "to a first order", weasel words meant to express something a
little more complex: the coefficient of drag (essentially the measure of
how aero a shape is) and frontal area are both fundamental to the drag
of an object (not as important as velocity, but reducing speed is not an
option:). using a few tricks, amateurs have a half a chance at making
accurate measurements of their frontal areas in various positions. If
one assumes that they have access to a power measurement system, one can
even check for relative power losses in each position.

Actually, if one didn't have a power measurement, but did have a hill
that was steep, but not so steep as to take the rider out of their tuck,
you could set up a test which would compare power outputs per position,
with wind effects minimized.

The problem is that for coefficient of drag measurements (actually,
total drag measurements), you can't beat a wind tunnel. So amateurs are
reduced to copying the pros, or finding a nearby indoor velodrome and
doing some timings to check speed for a position given constant power
output across multiple positions (thank you SRM).

One compromise which is consciously made is balancing aerodynamics
against power loss for any given position, and similar physiological
issues. Lance famously experimented with a TT bike known as "the narrow
bike" which had to be abandoned because although it demonstrated a
measurable aero advantage, he couldn't comfortably ride it.

I wouldn't imagine one of the world's best time triallists would drop E
at a party and fail a drug test, but...

You don't need a Weatherman to know which way the wind blows ...

--
Ryan Cousineau rcousine@xxxxxx http://www.wiredcola.com/
"I don't want kids who are thinking about going into mathematics
to think that they have to take drugs to succeed." -Paul Erdos
.

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