On Jul 15, 10:57*pm, wrote:
Mark my words wrote:
I watched the descent of the Tourmalet, the camera focused on a
lead breakaway rider pedaling hard at a cadence of 60-70rpm, with
the announcer claiming he was traveling at 60-65mph. *[what size
sprockets does that take?]
Damned good question. *I just took a downhill at 35 MPH upright on
a mountain bike with a 48/11 combo and could barely pedal that
fast, much less add any power or speed. *The hill was about 12% to
15% and fairly short but no matter what the gears I could not
imagine pedaling slowly at 60-65 MPH. *Maybe he was just moving his
legs to keep blood flowing. *I admit to doing that sometimes on a
long downhill where trying to pedal would be a waste of time.
Having ridden the Galibier where Phil Liggett has in years past
claimed descending speeds of 60mph I am certain that was bluster,
because coasting as fast as possible I and my ride companion could
barely achieve 40mph, the descent not being steep enough to go any
faster. *Even farther down, on the curvy, not steep enough,
Telegraph. *From experience 60mph requires at least a 13% grade as
straight sections of the Fedaia and Rombo passes in Italy
have. *In contrast, most roads that steep are not straight enough
for speeds above 35mph.
Beyond that, the strung out chasing field, all pedaling hard, are
apparently not shown in real time, because they appear to be
traveling over 40mph through curves without leaning into them
significantly.
Marketing!
No argument. *I think a multiple gear arrangement would be needed
for anything much over 45 to 50 MPH, pro or not.
Check out last week's Men Pro Race at Massachusetts
Fitrchburg/Longsjo Classic on YouTube:

*http://www.youtube.com/watch?v=L56BMBdjo1w.

The radar gun was calibrated by the police just before the event.
Many of the pros were riding 54 X 11 for the high speed descents

So! How do you achieve a speed like 100kmh+ pedaling that ratio at
60-70 rpm? *I have coasted down the Fedaia and Rombo passes at over
100kmh with a 50-13 engaged, but not pedaling because I cannot spin at
a rate well over 120rpm and why should I? *Just evaluating what power
would be required to affect such a speed makes the whole idea
preposterous.

Didn't see what you were watching, but I believe that they're called
freewheels for a reason. They could be pedaling and not applying any
force at all. Not sure that's what was happening, but you asked how.

R