Abstract: An adjustable, telescoping seat support allows the height of a bicycle seat to be adjusted to a number of seat height positions safely while bicycle is in motion. An elongated tubular seat post is clamped to a bicycle frame in a stationary position. A bicycle seat is attached to an end of a tubular seat holder that is slidably posited over the stationary tubular seat post. A coil spring placed inside the tubular seat holder provides an extending force on the tubular seat post and the tubular seat holder such that the seat support is capable of extending to a raised seat position and compressing to a lowered seat position. The seat is locked into raised and lowered seat positions by a plunger locking portion that is attached to the elongated tubular seat holder and which remains at a fixed position relative to the seat for all seat height positions.