Abstract: A belt drive for bicycles with a drive pulley rotated by the pedals of the bicycle and a driven pulley for driving the rear wheels of the bicycle. A V-belt connects the pulleys. Each pulley is made in sections with each section being an arc of a circle. These sections in collapsed position form a circle. The sections of each pulley may be moved outward to provide a larger diameter. A plate rotates in frictional contact with each pulley. To change the gear ratio a brake is applied against the friction plate to cause relative motion between the pulley and the complimentary friction plate.

Abstract: A bicycle has a belt and pulleys in place of the usual chain and sprockets. Each pulley has three (more of less) racways separated by discs (pulley walls). The discs (pulley walls) have openings that permit the belt to be shifted from one raceway to another raceway. A rotatable arm pivoted to the frame of the bicycle controls the shifting of the belt to the desired raceways. One end of the arm applies lateral pressure to the belt just before it arrives at the pulley associated with the driving pedals of the bicycle, to shift raceways for the driving pulley. Similarly the other end of the arm applies lateral pressure to the belt just before it enters the driven pulley to shift raceways of that pulley. Each end of the arm is biased by a main spring to apply vertical pressure to the belt to maintain it tight.