Abstract: A foldable bicycle comprises a front frame (1), a rear frame (21), and a seat tube (20). The front frame (1) and the rear frame (21) are foldable with respect to each other. In a first aspect, a single release clamp (12) releases the front frame from the rear frame in a single operation. This occurs by having the seat tube (20) slotted at the top (11). In a second aspect, the crank housing (34) is positioned in axial alignment with the seat tube (20) and one point (14) of folding occur below the crank housing. This aspect pertains to both a men's and a women's frame.

Abstract: A foldable bicycle designed so when the bicycle is folded, the front and rear frames bypass each other (non-overlapping) to permit a complete folding position and using a fold on or near the seat tube, and to maintain a rigid open riding position with simple standard fold restraining devices.

Abstract: A foldable tandem bicycle employs three separate frames joined at concentric seat tubes. The frames have quick release clamps to lock the frames into an open rigid orientation. The center frame has several configurations, male one having a closed complete frame with one diagonal brace and a female one with a pair of diagonal braces to eliminate the need for a top tube.

Abstract: A foldable bicycle has separate front and rear frames coupled to each other at a seat post formed by concentric frame members. A locking mechanism positions the frame members in either a rigid open or folded position. The pedal housing is located on the rear frame member either as an extension of the seat tube or positioned between the seat tube and the chain stays. The bicycle uses standard components to form the drive, brake and steering assemblies. In the folded state, the bicycle may be backpacked using available straps and webs that are attached to the front frame.