Abstract: A telescopic bicycle seat post system for permitting raising and lowering of a bicycle seat post over a wide range of lengths to adjust the overall height of the seat. The telescopic bicycle seat post system includes tubular upper and lower elongate members each having opposite upper and lower ends. The upper end of the lower elongate member telescopically receives therein the lower end of the upper elongate member. The lower end of the lower elongate member is designed for insertion into an upper opening of a seat tube of a bicycle frame. The upper end of the upper elongate member is designed for coupling a bicycle seat thereto. A generally c-shaped extension clamp is disposed around the lower elongate member adjacent the upper end of the lower elongate member. The extension clamp releasably holds the upper elongate member in a fixed position with respect to the lower elongate member.