Shin Length , from the point of rotation of the knee to center of the pedal spindle. See Figure 1 . Slope Force , Force exerted by gravity pulling a rider down a hill. Speed of the pedal , Vp , depends on the cadence, Cd , and the crank length, Cl . Strength Functions, supply torque to the pedaling model.
Muscles rotate the thighs about the hip and rotate the shin about the knee.
The strength and speed of the motions of the thighs and shins power the pedals. Thighs and shins can move in two directions. Muscles that bend the thigh and shin relative to the torso are called thigh and shin flexors. Muscles that move the thighs and shins in the opposite direction are called thigh and shin extensors. The torque produced by the thigh or shin can be different at each point in the range of motion and depends on the speed of motion.