"Friso" wrote in message
...
Yannick Tremblay yatremblay@bel1lin202.(none) wrote:
In article ,
Steve Freides wrote:
Mower Man wrote:

Isn't it the point that elliptical chain rings actually vary the gear
ratio? Forget the number of teeth, they're only there 'cos a chain is
used. Think of diameter. Variable diameter. Honest. Think drive belt?
Big pulley vs small pulley?

But big pulley versus small pulley, first of all, means something
different for belt drive than for one with teeth. If one pedal
revolution gets you 39 teeth spaced evenly apart, what's the difference
what the shape is? For a belt driven system, a change in shape could at
least mean a change in circumference.

For 1 complete revolution, there is no difference. Absolutely correct.

However what about 1/4 of a revolution or 1/8 of a revolution? Then
the diameter of the "big pulley" does differs.


I think that's the point of Biopace and this new system (has it got a
name yet?). The strength needed to rotate 1 cycle is equal, but with an
elliptical chainring this strength is supposed to be more equally
distributed.

Given the way everything is shaking and non-smooth there must be an
effect. I would think this effect is negative, also given the silent
passing of Biopace, but given the performance of Froome that doesn't
make sense.

I wonder: is it still possible to stand up on your pedals when you're
going uphill, or is this why Froome is almost always sitting?



Froome mostly sits because any energy used moving the body
up and down when standing is energy wasted compared to
not lifting the body and staying seated. A bicycle is a machine
which should be used for best mechanical advantage. Standing
and running on the machine as opposed to being seated on the
machine and spinning both pushing and pulling causes the machine
to become more efficient. Lifting the pedals while seated causes
more total energy to be put into the machine than lifting when
standing which mostly works against the inertia of the body mass
thus moving the body up and down with the push-pull and this
disrupts the smooth turning of circles which is more efficient
than some jerky motion.

Froome seems to have this insight. Then there's the factor
of wind resistance. Every pro should know that standing
causes more wind resistance. Why stand when it's going
to cost you watts and wear you out prematurely?

It's high time pro cyclists started relying less on drugs and
more on using their heads.

--
Sir Gregory