Variable speed transmission

Claim 1

In a bicycle having a crank-gear, a rear hub sprocket, chain means for transmitting power from the crank-gear to the rear hub sprocket and means for varying the speed ratio of the crank-gear to the rear hub sprocket, the improvement wherein said speed ratio varying means comprises an infinitely adjustable, variable speed transmission unit comprising: a first shaft; a sun gear fixed to said first shaft; a pinion carrier having spindles; at least two planetary pinions meshed with the sun gear, said planetary pinions being freely mounted onto said spindles; a second shaft keyed to said pinion carrier, said second shaft being coaxial with the first one; a ring gear freely mounted onto one of said first and second shafts, said ring gear extending over and meshing with said planetary pinions; a control gear fixed to said ring gear; a countershaft, said countershaft extending parallel to said first and second shafts; means to operatively connect the crank-gear to the countershaft so that said countershaft be driven by said crank-gear; a countershaft pinion keyed to said countershaft and operatively connected to said control gear so that said countershaft pinion and control gear rotate in opposite directions; a speed varying mechanism mounted between said first shaft and said countershaft to adjustably vary the relative speed of said countershaft with respect to said first shaft thereby varying torque applied to said control gear; and an output sprocket keyed onto any one of said first and second shafts, said output sprocket being operatively connected to said rear hub sprocket by a chain forming part of said chain means.