Chain drive for a bicycle

For use in a bicycle having a frame and wheels, a pedal operated chain drive comprising a wheel hub mounted for rotation on said frame, said hub having opposite end portions on opposite sides, respectively, of said frame, two sprocket devices mounted on said opposite end portions, respectively, for imparting rotation in a common direction to said hub;

• a pedal operated crank mounted for rotation on said frame, two coaxial sprockets secured to said crank for rotation therewith,
• said crank sprockets being axially spaced, parallel and disposed on opposite sides, respectively, of said frame;
• said two sprocket devices and said two crank sprockets being radially aligned, respectively, one sprocket device with one crank sprocket;
• and two chains on said aligned sprocket devices and crank sprockets, respectively, for imparting rotational drive from said crank to said wheel hub;
• said sprocket devices being free wheeling relative to said wheel hub when the bicycle is coasting forwardly but are drivingly engagable therewith when rotated in a foward direction at a rate faster than said wheel hub;
• said crank including a common shaft rotatably mounted on said frame, said crank sprockets being secured to the opposite ends, respectively, of said shaft such that said two chains lie in parallel planes, respectively, on opposite sides of said frame;
• said two sprocket devices being alike, said two crank sprockets being alike, and said two chains being alike, said sprocket devices, said crank sprockets and said two chains being symmetrically arranged on opposite sides of said frame and with respect to said wheel hub and crank;
• said two sprocket devices being commonly threadedly coaxially secured to said wheel hub end portions, respectively, means threaded oppositely on one of said end portions for further retaining the adjacent sprocket device on the same end portion, the threading of said means and the other sprocket device being in a tightening direction when forward driving force is imparted to said wheel hub.