Abstract: A speed change mechanism, principally for use on a bicycle, is provided in which a plurality of driving gears and an associated plurality of driven gears are coupled by a plurality of drive chains, such that each driving gear and its associated driven gear form a gear pair, with each gear pair providing a different input-to-output drive ratio. The driving gears are fixedly mounted to a driving shaft that is operatively coupled to a power input, such as a pedal and crank assembly of a bicycle, and the driven gears are rotatably disposed around a driven hub, with means provided for shifting between and engaging one of the driven gears to the driven shaft, with the driven shaft further operatively coupled to an output gear that will transmit power to a rear wheel of a bicycle, for example.

Abstract: A speed changing mechanism operable during both kinetic and static conditions. A gear 28 driven by bicycle pedals 30 in turn drives gear 32. Holes 38 in the face of the latter gear are engaged by gear 64 which is integral with output shaft 42. One end 72 of the output shaft is loosely supported in cup 78 whereby the shaft may be laterally shifted, then axially shifted so that gear 64 is withdrawn from one set of the holes 38, then reengaged with another set of the holes 38.