Crankarm length and saddle height.

[Ray1966]

If I change from a 172.5MM crank arm to a 170MM do you raise or lower the saddle? and vise versa ( 170 to 172.5 )

Thanks

 

[danfoz]

If you add length the the crankarm (increasing distance to the pedal at the bottom of the stroke), the saddle should be lowered to compensate. And visa versa - shorter crank, raise the saddle.

 

[Pat Stowe]

No change, as saddle hieght should be measured/deterrmined from the center of the bottom bracket/crank spindle, unless you have pain at knees- raise if pain at front, lower if pain at rear of knees - no more than 1 mm at a time

 

[alienator]

Actually, saddle height is dependent on cleat position and knee angle. BB height is only valid with respect to a given crank arm length.

 

[danfoz]

Originally Posted by Pat Stowe .

No change, as saddle hieght should be measured/deterrmined from the center of the bottom bracket/crank spindle, unless you have pain at knees- raise if pain at front, lower if pain at rear of knees - no more than 1 mm at a time

Pain in front of the knee can also be had too far forward over the BB. It transfers some of the extension from the glutes to the quads (even though glutes dictate hip extension and quads dictate leg extension both always fire to some degree) and this imbalance can put excessive strain on the point below the patella where the muscles attach especially if the transition is not gradual.