Abstract: A device for use for mounting a bicycle seat onto the frame of a bicycle is disclosed which uses a variable height mechanism which may be quickly and conveniently adjusted between two heights by moving the seat slightly to the side and then up or down to the selected position. A spring is used to provide both a torsion force retaining the mechanism in its locked position until the seat is to be adjusted, and a compressive force to bias the seat into its higher position. A guide mechanism is used to limit the relative movement between a lower segment and an upper segment to two locking positions at opposite ends of a guided vertical relative movement.