SP-1 2-Piece Seatpost The SP-1 seatpost is our tried-n-true 2-piece design made to work on any bike, any ride. Combining a lightweight, 2014 aluminum alloy shaft and a cold forged, aluminum alloy head, it delivers ride after ride and looks good doing it. Length - 400mm Diameter - 26.8mm, 27.2mm, 30.9mm, 31.6mm Offset - 20mm Material - 2014 Series Alloy