A bicycle and frame are disclosed, including a unitary front frame and a rear frame. The front frame includes a down tube rigidly connected to a head tube, a steerable front wheel assembly, and a crossbar rigidly fixed to one or both of the head tube and the down tube. The down tube is connected to the rear frame at a pivot proximate the bottom bracket shell. The rear frame includes a seat tube, a bottom bracket shell and a chainstay, all rigidly connected at the bottom bracket shell. A frame lock is disposed at the rearward end of the crossbar, for locking to the rear frame to substantially immobilize the pivot, placing the frame in a riding condition. The frame lock, when disengaged, facilitates relative movement of the front frame and the rear frame towards each other about the pivot, in a common vertical plane, to place the frame in a collapsed position, such that the down tube lies alongside the seat tube and the front frame and the rear frame are nested.