Patent ID: 8511655

Claim:
A seat post, comprising: a first piston set comprising a first cylinder, a first hollow piston, a gap, and a seal, the first cylinder for connecting to a frame of a bicycle, one end of the first hollow piston inserted into the first cylinder and having a through hole, the other end of the first hollow piston for connecting to a seat of the bicycle, the gap existing between the inside of the first cylinder and the outside of the first hollow piston and communicating with the inside of the first hollow piston, the seal disposed at the first cylinder for sealing the gap; a second piston set comprising a second cylinder and a second hollow piston, the second cylinder disposed in the first hollow piston and communicating with the inside of the first hollow piston, the cross-sectional area of the inside of the second cylinder the same as the cross-sectional area of the gap, the gap, the inside of the first hollow piston, and the second cylinder composing a first chamber; one end of the second hollow piston passing through the through hole and inserted into the second cylinder, the other end of the second hollow piston disposed in the first cylinder, the inside of the second hollow piston communicating with the inside of the first cylinder, the inside of the first cylinder and the second hollow piston composing a second chamber; a valve connecting the first hollow piston and the second cylinder for opening or closing the communication between the first hollow piston and the second cylinder; and a liquid stored in the first chamber; and a gas stored in the second chamber.