DRIVING APPARATUS FOR BICYCLE

摘要

PURPOSE: A bicycle driving apparatus is provided to effectively increase and decrease the number of rotations of the drive crank and the sprocket and to reduce the force for pedaling by employing a length-variable crank arm. CONSTITUTION: A bicycle driving apparatus comprises a housing(110) which is coupled with a bicycle frame, a crank arm(130) whose one end is connected to bicycle pedals so that the crank arm is rotated by pedaling of the bicycle rider, a drive crank(120) which has a rotary shaft to which the other end of the crank arm is connected so that the drive crank is rotated along with the rotation of the crank arm, an auxiliary gear(140) which is coupled with the housing and engaged with the drive crank, and an intermediate crank(150) which is engaged with the auxiliary gear and connected to a sprocket through a chain.