Don Wilson wrote:
>Thinking about the curved French Chandeze cranks on
>Ebay today
Those are functionally identical to straight cranks, aside from being heavier.
>and about Biopace chainwheels, etc., makes
>me ask if any one has ever tried asymmetric crank
>leverage factors to try to optimize pedalling by human
>beings with typically asymmetric leg strength. Just as
>persons have a dominant hand, they also have a
>dominant leg. The dominant leg is stronger. The non
>dominant leg is weaker.
Generally this relates to a leg length discrepancy, and the longer
leg tends to also be the stronger one.
>It makes some intuitive sense
>to design some kind of asymmetry into the leverage of
>the cranks to optimize pedalling between dominant and
>nondominant leg. Has anyone ever done this?
From my Cranks article:
"Mixing Lengths
"Riders who have one leg longer than the other sometimes attempt to compensate for this by using a shorter crank on the side with the shorter leg. I do not recommend this, however.
"When one leg is significantly shorter than another, the shorter leg is also usually weaker than the longer one. Since a short crank results in a higher gain ratio, this setup would ask the the weaker leg to push harder than the stronger one.
"A better way to deal with significant leg-length discrepancies is to build up the sole of the shoe, or to use longer bolts and spacer washers between the cleat and the shoe sole, or to build up the pedal by some sort of add on attachment.
"Leg length discrepancy can also be somewhat accommodated by putting the cleat on the foot with the longer leg farther back toward the heel.
"In some instances, deliberately setting the saddle slightly askew might also help."
Sheldon "http://sheldonbrown.com/cranks" Brown
--
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