Seat Post Shim Tube for MTB bikes Purpose and benefits The seat post shim tube is designed for MTB bikes and serves as a converter adapter to reduce seatpost size. It provides a strong, reliable size conversion between your frame and seatpost, helping you achieve a proper fit without replacing components. Size options and compatibility Available in multiple size options: 2 to 25.4 25.4 to 27.2 25.4 to 28.6 27.2 to 28.6 27.2 to 30.4 27.2 to 30.8 27.2 to 31.6 27.2 to 33.9 31.6 to 33.9 33.9 to 34.9 Compatible with different seat tube diameters including 22.2 mm, 25.4 mm, 27.2 mm, 31.6 mm, and 33.9 mm. Material and performance Made from aluminum alloy for a lightweight yet sturdy construction. The shim tube is precisely machined to resolve size mismatch between the frame and seat tube, supporting secure seating and stable height. Easy installation 1) Open the tube clamp 2) Insert the converter into the frame seat tube and push it to the end 3) Insert the seat tube into the converter 4) Adjust the height 5) Lock the tube clamp Use scenarios Scenario 1: Upgrading or refitting an MTB frame with a different seatpost diameter while preserving existing components. Scenario 2: Converting a frame with a non standard seat tube diameter to fit a compatible seatpost without replacing the frame. Scenario 3: Replacing or modifying a seatpost setup on bikes where precise height and secure clamping are required for improved fit and performance.