Abstract: A bicycle transmission includes a drive shaft having collinear input and output portions, an upstream end of the input portion being connected to the bicycle crank axle with a pair of bevel gears for transmitting rotational force therebetween. An epicyclic gear train is mounted intermediate the input and output portions. The gear train includes carrier plates coupled to the input and output portions with bearings and connected to one another by a carrier axle. A sun gear is fixedly attached to the output portion and engages a planet gear set rotatably mounted to the carrier axle. Ring gears are positioned to mesh with corresponding planet gears. A selected ring gear may be halted to establish a desired transmission ratio by which rotational force is transmitted between input and output portions. The output portion is connected to the rear wheel axle with a pair of bevel gears.