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Main
Date: 26 Oct 2007 02:18:27
From:
Subject: Power to drive wheels
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Hey,
Can anyone explain or point me to any source on the net, regarding the
power requirements of riding, particularly that needed to simply
overcome the inertia of the wheels from rest, that to get it moving,
and that to accelerate..and how much "rotational weight" counts in.
Some solid sources would be nice, I want to put this beast of a myth
to rest with a cycling friend and an LBS owner.... its almost
irritating now.
Ron
http://cozybeehive.blogspot.com
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Date: 26 Oct 2007 17:51:07
From: Ron Ruff
Subject: Re: Power to drive wheels
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On Oct 25, 8:18 pm, ron.r.geo...@gmail.com wrote:
> Some solid sources would be nice, I want to put this beast of a myth
> to rest with a cycling friend and an LBS owner.... its almost
> irritating now.
Another myth that was floating around last year was that the rotating
weight really slows you down on a climb... since at a low cadence you
are constantly accelerating. But in reality you decelerate too, and a
higher rotating inertia actually helps since it reduces the
fluctuations in speed. Of course the higher weight is not good on a
climb, but if you had to put all your weight in the rims, that would
be the best place for it. In other words a 20lb bike with 4 lb rims
will be faster than a 20lb bike with 2lb rims.
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Date: 26 Oct 2007 09:39:55
From: joseph.santaniello@gmail.com
Subject: Re: Power to drive wheels
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On Oct 26, 4:18 am, ron.r.geo...@gmail.com wrote:
> Hey,
>
> Can anyone explain or point me to any source on the net, regarding the
> power requirements of riding, particularly that needed to simply
> overcome the inertia of the wheels from rest, that to get it moving,
> and that to accelerate..and how much "rotational weight" counts in.
> Some solid sources would be nice, I want to put this beast of a myth
> to rest with a cycling friend and an LBS owner.... its almost
> irritating now.
>
> Ron
>
> http://cozybeehive.blogspot.com
This Gent has done the work for you:
http://www.charles.whitaker.name/wheels.html
Joseph
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Date: 26 Oct 2007 15:42:13
From: bicycle_disciple
Subject: Re: Power to drive wheels
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On Oct 25, 10:47 pm, carlfo...@comcast.net wrote:
> On Fri, 26 Oct 2007 02:18:27 -0000, ron.r.geo...@gmail.com wrote:
> >Hey,
>
> >Can anyone explain or point me to any source on the net, regarding the
> >power requirements of riding, particularly that needed to simply
> >overcome the inertia of the wheels from rest, that to get it moving,
> >and that to accelerate..and how much "rotational weight" counts in.
> >Some solid sources would be nice, I want to put this beast of a myth
> >to rest with a cycling friend and an LBS owner.... its almost
> >irritating now.
>
> >Ron
>
> >http://cozybeehive.blogspot.com
>
> Dear Ron,
>
> When the site is up, analytic cycling has lots of calculators, which
> include one for comparing the effect of heavier and lighter wheels,
> side by side.
>
> http://www.analyticcycling.com/
>
> Right now, the site is down.
>
> Short answer, rotational weight doesn't make much difference between
> the acceleration of an ordinary and a light wheelset.
>
> The speed difference is so small that you need a calculator or at
> least a good stopwatch and lots of test runs to show a time difference
> between an ordinary and a light wheel set.
>
> A typical rider weighs about ten times as much as his whole bicycle,
> thirty times as much as his wheelset, and even more compared to the
> part of his wheelset that's actually out at the rim.
>
> Flip a bike upside-down, fit a speedometer to the rear, and crank a
> couple of wheels up to 30 mph with one hand. You'll have trouble
> distinguishing one from the other.
>
> To a racer, the trivial difference may be worth a lot.
>
> To most bicyclists, the difference lies in psychology, not in any
> speed increase measured in actual riding. Without the price tag and
> the claimed weight reduction, they'd be unlikely to notice the
> improvement. After all, most riders spend very little accelerating all
> out from a standing start to top speed--which may be why they like to
> fantasize about how shaving 200 grams off the rims of an 80,000 gram
> package is going to turn them into Lance Armstrong.
>
> Cheers,
>
> Carl Fogel
Thanks Carl, that website is up and functioning. I'm going to use it.
Its unfortunate that the sales people think we're all a bunch of
fools. The famous sales pitch of "rotational" weight is just junk
science. I feel a larger than normal seat tube can do as much drag
reduction as changing a rear wheel to something more aero or
lightweight... :)
Ron
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Date: 26 Oct 2007 06:26:09
From: dustoyevsky@mac.com
Subject: Re: Power to drive wheels
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On Oct 25, 9:47 pm, carlfo...@comcast.net wrote:
> On Fri, 26 Oct 2007 02:18:27 -0000, ron.r.geo...@gmail.com wrote:
> >Hey,
>
> >Can anyone explain or point me to any source on the net, regarding the
> >power requirements of riding, particularly that needed to simply
> >overcome the inertia of the wheels from rest, that to get it moving,
> >and that to accelerate..and how much "rotational weight" counts in.
> >Some solid sources would be nice, I want to put this beast of a myth
> >to rest with a cycling friend and an LBS owner.... its almost
> >irritating now.
>
> >Ron
>
> >http://cozybeehive.blogspot.com
>
> Dear Ron,
>
> When the site is up, analytic cycling has lots of calculators, which
> include one for comparing the effect of heavier and lighter wheels,
> side by side.
>
> http://www.analyticcycling.com/
>
> Right now, the site is down.
>
> Short answer, rotational weight doesn't make much difference between
> the acceleration of an ordinary and a light wheelset.
>
> The speed difference is so small that you need a calculator or at
> least a good stopwatch and lots of test runs to show a time difference
> between an ordinary and a light wheel set.
The difference is always there, no matter how tiny (or large).
It might be so small that it is difficult to measure in the real world
("requiring repeated test runs"), as opposed to estimating via
calculation, but it is always there.
> A typical rider weighs about ten times as much as his whole bicycle,
> thirty times as much as his wheelset, and even more compared to the
> part of his wheelset that's actually out at the rim.
>
> Flip a bike upside-down, fit a speedometer to the rear, and crank a
> couple of wheels up to 30 mph with one hand. You'll have trouble
> distinguishing one from the other.
>
> To a racer, the trivial difference may be worth a lot.
For the pros, even one little second at the end of 170 miles is big
when there's a Monument at stake.
To some of the amateur "weekend warriors", the stakes are different
but (apparently) no less important.
> To most bicyclists, the difference lies in psychology, not in any
> speed increase measured in actual riding. Without the price tag and
> the claimed weight reduction, they'd be unlikely to notice the
> improvement. After all, most riders spend very little accelerating all
> out from a standing start to top speed--which may be why they like to
> fantasize about how shaving 200 grams off the rims of an 80,000 gram
> package is going to turn them into Lance Armstrong.
Some may be seduced by ad hype-- exaggerated claims of efficiency or
"time advantage" for various cycling equipage. But, there's usually a
reality check on the first ride or two with the new superstuff.
IMHO the gear psyche is partly in the price tag (pride of ownership
figuring in), the "zoot factor", peer pressure, pecking order, and so
on. But, as an overweight acquaintance once told me, over a hearty
breakfast, IRT a set of light and semi-aero wheels: "I'll buy that ten
seconds!".
Related, and some indication that ESP or some form of hidden
communication exists among humans: One of the good local Vet racers
showed up on a Sunday morning ride on his brand new superbike, carbon
carbon everywhere, lightness and pride of ownership abounding, etc.
Stopped at a traffic light after a hilly first few miles of the ride,
the whole group let him roll away solo at the green. He was a good 20
yards out before he caught on. A good prank, enjoyed by all. "You
still gotta pedal the thing". --D-y
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Date: 26 Oct 2007 05:50:26
From: Qui si parla Campagnolo-www.vecchios.com
Subject: Re: Power to drive wheels
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On Oct 25, 8:18 pm, ron.r.geo...@gmail.com wrote:
> Hey,
>
> Can anyone explain or point me to any source on the net, regarding the
> power requirements of riding, particularly that needed to simply
> overcome the inertia of the wheels from rest, that to get it moving,
> and that to accelerate..and how much "rotational weight" counts in.
> Some solid sources would be nice, I want to put this beast of a myth
> to rest with a cycling friend and an LBS owner.... its almost
> irritating now.
>
> Ron
>
> http://cozybeehive.blogspot.com
Carl does a great job of answering your question..but in a
nutshell..the energy required to accelerate a bike and rider from rest
is the mass of the bike and rider. Where the weight is doesn't really
matter. 180 pound rider with a 15 pound bike with the 'weight' of the
wheels at the hub or a 175 pound rider with a 20 pound bike with
conventional wheels..same energy to accelerate. The LBS owner ought to
stop reading wheel ads.
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Date: 25 Oct 2007 20:47:59
From:
Subject: Re: Power to drive wheels
|
On Fri, 26 Oct 2007 02:18:27 -0000, ron.r.george@gmail.com wrote:
>Hey,
>
>Can anyone explain or point me to any source on the net, regarding the
>power requirements of riding, particularly that needed to simply
>overcome the inertia of the wheels from rest, that to get it moving,
>and that to accelerate..and how much "rotational weight" counts in.
>Some solid sources would be nice, I want to put this beast of a myth
>to rest with a cycling friend and an LBS owner.... its almost
>irritating now.
>
>Ron
>
>http://cozybeehive.blogspot.com
Dear Ron,
When the site is up, analytic cycling has lots of calculators, which
include one for comparing the effect of heavier and lighter wheels,
side by side.
http://www.analyticcycling.com/
Right now, the site is down.
Short answer, rotational weight doesn't make much difference between
the acceleration of an ordinary and a light wheelset.
The speed difference is so small that you need a calculator or at
least a good stopwatch and lots of test runs to show a time difference
between an ordinary and a light wheel set.
A typical rider weighs about ten times as much as his whole bicycle,
thirty times as much as his wheelset, and even more compared to the
part of his wheelset that's actually out at the rim.
Flip a bike upside-down, fit a speedometer to the rear, and crank a
couple of wheels up to 30 mph with one hand. You'll have trouble
distinguishing one from the other.
To a racer, the trivial difference may be worth a lot.
To most bicyclists, the difference lies in psychology, not in any
speed increase measured in actual riding. Without the price tag and
the claimed weight reduction, they'd be unlikely to notice the
improvement. After all, most riders spend very little accelerating all
out from a standing start to top speed--which may be why they like to
fantasize about how shaving 200 grams off the rims of an 80,000 gram
package is going to turn them into Lance Armstrong.
Cheers,
Carl Fogel
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