Thudbuster ST Seatpost - 31.6 mm Thudbuster Short Travel (ST), Designed specifically with the rigors of e-bikes and daily commuting in mind, the Thudbuster ST includes 50 mm of travel to significantly diminish shocks and impacts from broken pavement, cobblestones or any other mixed surfaces, Able to support riders up to 330 lbs (150 kg) and incorporates a tool-, interchangeable elastomer system to quickly and easily adjust the seat post for a variety of rider weights, The Thudbuster Parallel Linkage technology stays in the direct path of the natural travel of the rear wheel*as a bump lifts the back of a bicycle, the rear wheel pushes up and forward into the rider, 50 mm / 1.97" of travel, 0 mm (unweighted) setback, Medium firm elastomer pre-installed from the factory with soft and firm elastomers included, Pivots * Threaded, serviceable, hard anodized aluminum axels flanged polytetrafluoroethylene (PTFE) bushings