Abstract: A new bicycle seat post shock absorber for dampening impacts and vibrations directed though the bicycle frame to a bicycle seat. The inventive device includes a cylindrical seat post plunger inserted into the hollow interior of a tubular sleeve member designed for insertion into the lumen of a tubular frame member of a bicycle. A spring member disposed around the seat post plunger functions as a biasing means biases the seat post plunger away from the sleeve member. A movement limiting shoulder included on the seat post plunger limits the amount of insertion of said seat post plunger into the sleeve member.