Automatic transmission for bicycle
 An automatic transmission for bicycle including a support shaft with an interior created by a hollow shaft having a long hole drilled thereinto, and fixed grooves formed on its outer surface at regular intervals; a movable casing mounted on the support shaft; a fixation ball attached to the inside of the movable casing to mate with the fixed grooves; a pin inserted into the movable casing to pass through the long hole; a speed-change wire connected to the pin; a coil spring loaded between one side of the movable casing and a clamping bolt; a plurality of rotary balls seated in an outer groove of the movable casing to slightly protrude from the outer groove so that the rotary balls rotate along a thread bottom formed on an inner surface of a revolving body; a plurality of needle bearings provided to an outer surface of the revolving body; a friction band provided to the outside of the needle bearings, and having one side fixed to a rotating axle; and a weight provided to the friction band's other side and exposed to the outside of the rotating axle through an outlet. 
B B Y
B62M B62M Y10T
inventional inventional additional
Yong Chul
Jung