A drive for a bicycle includes an auxiliary sprocket wheel assembly having two sets of at least three sprocket wheels associated in each assembly attached to a common axle, one of said sets having a larger diameter than the other set. Each set is provided with a derailleur for changing associated sprocket chains from one sprocket of the set to another. Use of the auxiliary sprocket wheel assembly together with derailleurs on the regular pedal and drive wheel sprockets enables very high speeds to be attained by the average rider.