An auxiliary bicycle transmission for a bicycle has a crossbar formed by a telescoping bar slidably mounted in an outer channel member. One end of a half chain or half V-belt is connected to the telescoping bar, the other end is connected by means of a spring to the upper end of a down tube, and the chain or V-belt that engages a freewheeling sprocket or pulley so that when the telescoping bar extends out of the outer channel member against the spring force, the freewheeling sprocket rotates and provides additional motive force to the standard transmission of the bicycle.