Landis' aerobars

"Tom Kunich" wrote in message
ink.net...

No, what it might mean is that all the photographs we've seen were of
riders sitting up for turns, ending their wind tunnels tests or that sort
of thing. In other words, the teams didn't want photos of their "working"
positions showing. Why should they spend money for testing and then throw
the majority of it away by showing the competition?


Since when do teams have control over whether photographs of riders in turns
or in their tucked position are published?

Ronald wrote:
I've seen three photographs now
of the Rabobank guys and unless those photographs were purposely staged
to show the wrong sort of positions, I can't see how those positions
could possibly result in good aero results.

Rasmussen (also Rabobank) uses a position like Landis:
http://www.cyclingnews.com/photos/20...ikes4/IMG_0469


Yeah, but that's just in an effort to keep on the fricken bike!

Carl Sundquist wrote:
"Tom Kunich" wrote in message
ink.net...

No, what it might mean is that all the photographs we've seen were of
riders sitting up for turns, ending their wind tunnels tests or that sort
of thing. In other words, the teams didn't want photos of their "working"
positions showing. Why should they spend money for testing and then throw
the majority of it away by showing the competition?

Since when do teams have control over whether photographs of riders in turns
or in their tucked position are published?

I was thinking more along the lines of photographers taking more
"interesting" pictures of riders full faces and not of someone in a
full tuck etc.

In article ,
"Steve Freides" wrote:

"Ryan Cousineau" wrote in message
...
In article ,
"Steve Freides" wrote:

"jeremy" wrote in message
oups.com...
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/20...e065/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 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

Ryan Cousineau wrote:

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).

Given the inherent measurement characteristics of on-bike power meters, I
don't think runs at constant power is the best way to do it at all.

In article ,
"Robert Chung" wrote:

Ryan Cousineau wrote:

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).

Given the inherent measurement characteristics of on-bike power meters, I
don't think runs at constant power is the best way to do it at all.

Since you're the guy who published the Rosetta Power Files, I cede the
field. What's the issue, and what's the better way?

-RjC.

--
Ryan Cousineau 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

"Ryan Cousineau" wrote in message
...
In article ,
"Steve Freides" wrote:

"Ryan Cousineau" wrote in message
...
In article ,
"Steve Freides" wrote:

"jeremy" wrote in message
oups.com...
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/20...e065/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:

-snip-

No. I figure this is something for pro's and their hired guns, and most
of the rest of us should just go out and pedal as hard as we can. I
realize many folks here race but I'm not one of them - I ride, and I
enjoy following bike racing, but that's as far as it goes for me. When
I want to be aero, I grab my bars near the stem and hunker down and
that's good enough for me.

-S-

Ryan Cousineau wrote:
Robert Chung wrote:
Given the inherent measurement characteristics of on-bike power
meters, I don't think runs at constant power [across varying positions]
is the best way to [estimate CdA] at all.

What's the issue, and what's the better way?

An example of a constant power test is a roll-down test: the power is
fixed at zero. It turns out that even tiny amounts of wind and tiny
amounts of grade can screw up these tests. Most people try this by rolling
down a hill, but Wilson's MIT students used to try to do roll-down tests
on the flattest and least windy venues they could find: down the long
linoleum hallways of the buildings.The precision was affected by whether
doors along the hallway were open or closed, as well as the skill of the
rider.

Even if you have an on-bike PM, most people don't do constant power runs
on the road because the PM display is too jumpy and there's too much
latency to use as a proper control. Instead, most people think that the
best way to estimate CdA with a power meter is to do constant speed runs
on flat windless surfaces and then solve algebraically for the drag. They
do this because constant speed reduces the acceleration to zero (which
simplifies the calculation). However, it's hard to find venues that are
both flat enough and windless enough (even the hallways at MIT), and the
on-bike PM display is still a little too jumpy for control. I have data
files from guys who've tried just this on the road and they end up with
very poor estimates of CdA.

So, from a statistical analytical point of view, it's better to bite the
bullet and keep track of the accelerations. Vary the speed and power. It's
more of a pain but the estimates are better.

On 2006-06-04 22:23:05 -0400, "Robert Chung" said:

Here's how Landis set up his aerobars:
http://www.cyclingnews.com/photos/20...phine06-pg-012

For

comparison, here's Menchov:
http://www.cyclingnews.com/photos/20...phine06-pg-009

And

Landis has been using Kraig Willett (who used to hang around rec.tech a
lot) to get to that position...

http://www.cyclingnews.com/tech.php?...es/levi_tunnel

Here's what he does for fun:

http://biketechreview.com/stems/extremeload.htm#Updated!

In article ,
"Robert Chung" wrote:

Ryan Cousineau wrote:
Robert Chung wrote:
Given the inherent measurement characteristics of on-bike power
meters, I don't think runs at constant power [across varying positions]
is the best way to [estimate CdA] at all.

What's the issue, and what's the better way?

An example of a constant power test is a roll-down test: the power is
fixed at zero. It turns out that even tiny amounts of wind and tiny
amounts of grade can screw up these tests.

Even if you have an on-bike PM, most people don't do constant power runs
on the road because the PM display is too jumpy and there's too much
latency to use as a proper control. Instead, most people think that the
best way to estimate CdA with a power meter is to do constant speed runs
on flat windless surfaces and then solve algebraically for the drag. They
do this because constant speed reduces the acceleration to zero (which
simplifies the calculation). However, it's hard to find venues that are
both flat enough and windless enough (even the hallways at MIT), and the
on-bike PM display is still a little too jumpy for control. I have data
files from guys who've tried just this on the road and they end up with
very poor estimates of CdA.

So, from a statistical analytical point of view, it's better to bite the
bullet and keep track of the accelerations. Vary the speed and power. It's
more of a pain but the estimates are better.

Thanks for the answer. That's just good stuff. And it reinforces my
violent predjudice against TTs for amateurs .

Now, is there any way we can use this data to fight off the arguments of
the HPV set? There's another violent predjudice I need confirmed.

Everything that's wrong with usenet,

--
Ryan Cousineau 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