US Patent 11661129 Pneumatic only height adjust seat post assembly

A seat post assembly for a bicycle includes a first tube having a first distal end and a second tube having a second distal end. A distance between the first distal end of the first tube and the second distal end of the second tube is at a maximum when the first tube is in a first position relative to the second tube. The seat post assembly also includes a first chamber and a second chamber that are fluidly coupleable. The first chamber is a positive fluid chamber, and the second chamber is a negative fluid chamber. The seat post assembly includes a fluid volume disposed in the first chamber and the second chamber. The fluid volume includes a compressible fluid. The first chamber is configured to act as a spring configured to bias the first tube towards the first position relative to the second tube.