Originally Posted by
ajcurl
Im no rocket scientist at all about bike fit and bike geometry etc......but with a proper bike fit, as far as your knee in relation to the center of your pedal, shouldn't it be the same no matter which crank arm you have?
Your knee has to bend more with a longer crank. You also tend to pedal at a slower cadence with a longer crank that is also harder on knees.
I'm 5'7 and use
165 SS is easy to a get a high cadence,
175 is on a MTB for extra leverage on steep climbs.
170 and 172.5 are on road bikes.
Different tools for different jobs.