Forces that the rider applies to the pedals, saddle and handle during starting, climbing and speeding are estimated from photograph records using static mechanics. And torques on each joint and compression on L5/S1 disc are calculated. So we can suggest the guideline about frame size, especially handle height, distance between handle and saddle. When handle height decreases and horizontal distance between handle and pedal decreases in apart hip from sadde for larger pedal force, the compression on L5/Sq disc, the force on hand and sum of torques on each joint decreases. When handle height is higher in normal speeding, the force on handle and sum of torques on each joint decreases. The maximal force on pedal that the rider exert is higher according as handle height decreases.
