We make the seatpost in a 27.2 and 30.9 diameter. Shims are available for other sizes including 28.6, 29.2, 29.4, 29.6, 29.8, 30.0, 30.2, 30.4, 30.8, 30.9, 31.6, 31.8, 34.9. We also make a 26.8 and 27.0 mm post. If you order a 30.9 diameter you must choose “No Shim” or “With Shim” which is a 27.2 with shim.

Your seatpost diameter can be found on the lower portion of the Seatpost.