A bicycle transmission assembly that is mountable to a bottom bracket shell of a bicycle frame. The bicycle transmission generally includes an input crank assembly, an output chainring, a planetary gear mechanism, a control system and a mounting system. The output chainring engages a bicycle drive chain that includes a plurality of chain links. The planetary gear mechanism includes a ring gear and provides a plurality of transmission paths. The planetary gear mechanism is mounted coaxially about the shell axis. The control system is operatively connected to the planetary gear mechanism for selecting one of the plurality of transmission paths. The mounting system mounts the planetary gear mechanism and the control system to the bottom bracket shell. At least one chain link overlaps the ring gear as viewed along the shell axis. The at least one chain link engages the output chainring.