Originally Posted by
SweetLou
The only thing I can think of is that if your cranks are too long for your legs, you will bend your knee too much. When this happens, you don't have much power until your leg becomes more extended. But, since women have longer legs than men, wouldn't it be better to have longer cranks? Maybe Trek thinks because women are not as strong as men, they need shorter cranks so that they can spin faster instead of mashing. Shorter cranks promote higher cadence.
Having been married to a pixie for eons, I've have plenty of scars from the fit fight
The issue with longer cranks for small persons is that their knees are pushed higher at the top of the stroke than a 'normal' person would experience. Their knee is bent at a pretty sever angle compared to the 'normal' person. The best angle for leverage off the top dead center of the stroke is 90 degrees. But the small person's knee is at less than 90 degrees. They are having to push more with their calves and less with their quads. To reach the proper leverage, they have to move further down the stroke, well into the power curve. It's similar to riding with a saddle that too low.
You could move the saddle higher to get the proper angle at the top of the stroke but now they'd have to rock their hips to reach the bottom of the stroke...not a good thing. It pulls all kinds of muscles in odd ways that results in painful riding. And scrubbing your nether regions on a saddle that is too tall all day results in other kinds of pain that result in no lovin'...for days
