Crank Length Calculator

Calculate optimal crank arm length based on your inseam and riding style. Proper crank length improves pedaling efficiency and reduces knee strain.

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How It Works

Crank length is measured from the center of the bottom bracket axle to the center of the pedal spindle hole. Standard sizes range from 165mm to 175mm in 2.5mm increments. The general rule is inseam (mm) x 2.1 for road, slightly longer for MTB (more torque), shorter for triathlon (hip angle). Shorter cranks allow higher cadence and are easier on knees. Longer cranks give more leverage for climbing. Most riders never change from stock, but proper crank length can reduce injury risk significantly.