Dans le message de ,
Dan Connelly a réfléchi, et puis a
déclaré :
Tuschinski wrote:

Nope, pure and simple aerodynamics. Another nice one: Aerodynamics
have more effect than weight on TdF cols. The speed of the pros and
the gradient make weight a much smaller factor. It's why the
Lightweight (German Brand) wheels are popular, light AND aerodynamic.
The big disadvantage is that high rims are pretty unforgiving. Using
them 6-7 hours is very uncomfortable, even for most pros.

It's also one of the reasons why drafting behind a teammate still is
important in the mountains.


Wind resistance: 1/2 rho Cd A v^2, where rho ~ 1.1 kg/m^2, Cd A ~ 0.3
m^2 Mass-proportional force: M g (grade + Crr), where Crr is rolling
resistance ( 0.6%, typical), M is total system mass (75 kg, typical),
g is gravity (9.8 m/sec^2)
These are equal for:

v = sqrt [ 2 M g ( grade + Crr ) / (rho Cd A) ]

For example, a 7% grade: 19.3 mps = 69.5 kph

So if you can climb a 7% grade at 69.5 kph, then wind resistance is
contributing as much as weight....

You have to stop following me on my morning rides !! My computer rounds to
70/