When is that new power-measuring device arriving?

In article , bbaka
wrote:

Robert Chung wrote:
bbaka wrote:

Robert Chung wrote:


Drivetrain losses aren't all that high. Here's a comparison of the SRM
and Power Tap (and the Polar) on the same bike:

http://mywebpage.netscape.com/rechun...a/rosetta.html

That link is broken, at least for now.


Sigh. Nope, the link's not broken; yes, it's for one of those freebie
sites that's (ahem) underpowered. Usually, but not always, when you get a
"page not found" you can hit the reload current page button and it will
appear.


Power at the wheel usually equals speed.

No.


Really? So you are implying that more power reduces your speed? I think
we were talking about level ground road biking with no wind. More power
equals more speed in this universe. Negative power is possible with the
brakes and that makes heat, which, again, is power.

Please qualify your blanket 'No.'


In my universe, but perhaps not yours, roads aren't flat, the winds do
blow, speeds aren't constant, and position changes. We're talking about
on-bike power measuring devices. Why would you need such a thing if power
equals speed? All you'd need is a speedometer.


I haven't seen a mention that this was just for indoor use and have seen
a graph of power over a trip, so we need to be all talking about indoor
or outdoor. Indoor is simple to put on a trainer so if that is the
direction of the discussion, what is the big deal? How many people train
indoors anyway???
Bill Baka

Bill, I think you've now argued both sides of the argument. What Robert
is saying is that power, while a useful measure of a rider's ability, is
by no means the only factor in performance. Remember how we were talking
about the importance of aerodynamics? There are many cases where a rider
with superior power output over a TT has been beaten by a rider with
inferior power and better aerodynamics (through some combo of
positioning, equipment, and morphology).

Similarly, power to weight mattes more than power once the road turns
uphill, but even there aero matters more than you might think.

--
Ryan Cousineau, http://www.wiredcola.com
Verus de parvis; verus de magnis.

Ryan Cousineau wrote:

Bill, I think you've now argued both sides of the argument. What Robert
is saying is that power, while a useful measure of a rider's ability, is
by no means the only factor in performance. Remember how we were talking
about the importance of aerodynamics? There are many cases where a rider
with superior power output over a TT has been beaten by a rider with
inferior power and better aerodynamics (through some combo of
positioning, equipment, and morphology).

Similarly, power to weight mattes more than power once the road turns
uphill, but even there aero matters more than you might think.

I wasn't here to argue either side of the issue really. It just makes
more sense to me to measure the power of a rider under real conditions
like maybe a sprint ahead of the peloton. What tweaked my interest in
power was that "Beyond category" sprint that Lance did in last years TdF
that had even the commentators at a loss for words. He was in the
horsepower range, not people power, but by how much? Personally I can't
do much of anything in a gym setting since it is so boring and there is
no motivation to pedal to better scenery.
Bill Baka

In article , bbaka
wrote:

Ryan Cousineau wrote:

Bill, I think you've now argued both sides of the argument. What Robert
is saying is that power, while a useful measure of a rider's ability, is
by no means the only factor in performance. Remember how we were talking
about the importance of aerodynamics? There are many cases where a rider
with superior power output over a TT has been beaten by a rider with
inferior power and better aerodynamics (through some combo of
positioning, equipment, and morphology).

Similarly, power to weight mattes more than power once the road turns
uphill, but even there aero matters more than you might think.

I wasn't here to argue either side of the issue really. It just makes
more sense to me to measure the power of a rider under real conditions
like maybe a sprint ahead of the peloton. What tweaked my interest in
power was that "Beyond category" sprint that Lance did in last years TdF
that had even the commentators at a loss for words. He was in the
horsepower range, not people power, but by how much? Personally I can't
do much of anything in a gym setting since it is so boring and there is
no motivation to pedal to better scenery.
Bill Baka

The best answer to your question is probably available from Dr Michele
Ferrari, who has posted on his site about VAM, a way of indirectly
estimating power and performance from climbing rates:

http://www.53x12.com/do/show?page=article&id=21

If we can come up with some plausible numbers for Lance's rate of climb,
distance, time elapsed, and the aero drag, we should be able to
calculate Lance's rough power output.

http://www.cyclingnews.com/road/2004...ri/?id=default

But the short answer is that Lance claims a peak power output of 600 W:

http://www.lancearmstrong.com/about_stats.htm

The grain of salt is that the nature of human power is that sustained
power output drops off dramatically from the peak. On his endurance
training rides, Lance claims an average power output of 245-280 W.

--
Ryan Cousineau, http://www.wiredcola.com
Verus de parvis; verus de magnis.

Ryan Cousineau wrote:
If we can come up with some plausible numbers for Lance's rate of climb,
distance, time elapsed, and the aero drag, we should be able to
calculate Lance's rough power output.

But the short answer is that Lance claims a peak power output of 600 W:

The grain of salt is that the nature of human power is that sustained
power output drops off dramatically from the peak. On his endurance
training rides, Lance claims an average power output of 245-280 W.

Based on the 2004 Alpe d'Huez ITT, I calculate his hour power to be around
400 W.

Ryan Cousineau wrote:
The best answer to your question is probably available from Dr Michele
Ferrari, who has posted on his site about VAM, a way of indirectly
estimating power and performance from climbing rates:

http://www.53x12.com/do/show?page=article&id=21

If we can come up with some plausible numbers for Lance's rate of climb,
distance, time elapsed, and the aero drag, we should be able to
calculate Lance's rough power output.

http://www.cyclingnews.com/road/2004...ri/?id=default

But the short answer is that Lance claims a peak power output of 600 W:

http://www.lancearmstrong.com/about_stats.htm

I went here and the peak power of only 600 W seems a bit low considering
his sometimes nearly impossible sprints. Those are peak power over maybe
15-20 seconds so may be hard to actually measure.

The grain of salt is that the nature of human power is that sustained
power output drops off dramatically from the peak. On his endurance
training rides, Lance claims an average power output of 245-280 W.

This one I believe since that is a good fraction of a horsepower which I
believe is at 745 watts, so he is at the top of what a human his size
could possibly put out. A 6'6" rider would have to put out better than
one half horsepower to be competitive, especially on the climbs where
raising ones weight to a higher elevation eats the power.

Bill Baka

In article , bbaka
wrote:

Ryan Cousineau wrote:
The best answer to your question is probably available from Dr Michele
Ferrari, who has posted on his site about VAM, a way of indirectly
estimating power and performance from climbing rates:

http://www.53x12.com/do/show?page=article&id=21

If we can come up with some plausible numbers for Lance's rate of climb,
distance, time elapsed, and the aero drag, we should be able to
calculate Lance's rough power output.

http://www.cyclingnews.com/road/2004...ri/?id=default

But the short answer is that Lance claims a peak power output of 600 W:

http://www.lancearmstrong.com/about_stats.htm

I went here and the peak power of only 600 W seems a bit low considering
his sometimes nearly impossible sprints. Those are peak power over maybe
15-20 seconds so may be hard to actually measure.

Well, my impression of Lance's hill-climbing prowess is that he isn't
sprinting. It's just that when he attacks, he's putting out more power
than any other rider can sustain, so he moves away rapidly. Note that
small changes in power output (or power-to-weight ratio, really) make
big differences in speed on climbs, because the effort required to
overcome gravity increases linearly, while the effort required to
overcome aerodynamic drag increases as the...square? of velocity.

There is still an aero component at the climbing speeds of pro cyclists,
but it is considerably diminished compared to their usual flatland pace.

So, he's not sprinting, he's just that much better.

I'd also bet that Lance has not seriously trained for sprinting power in
several years, since it's basically not part of his game plan. He has to
do huge work to prepare for the recovery elements and get his aerobic
power higher, he works hard on TT performance, and he has to be able to
climb like a Spaniard, but the sprinting he leaves for others.

--
Ryan Cousineau, http://www.wiredcola.com
Verus de parvis; verus de magnis.

Ryan Cousineau wrote:
while the effort required to
overcome aerodynamic drag increases as the...square? of velocity.

Aero drag increases with the square of velocity so power to overcome that
drag increases with the cube.