USE Seat Post Shim, 30.9mm Inner Diameter x 34.9mm Outer Diameter

The USE shim system allows you to fit a seat post into virtually any frame size. Our shims are made to 100mm length and are longer than other shims on the market giving your seat post much better support inside the frame. All shims are designed with a "top lip" to stop shim sliding into the frame. Shims are available in Aluminum and Thermo Plastic, despite the latter being a lighter solution its material characteristics limit the thickness of the ID - OD measurements. Aluminum is used to achieve the thinnest shims as it is a more robust material. Rolled Aluminum shim - the very thinnest shims are rolled from sheet metal. 25.4mm shims need to be so thin as they are etched down in acid to the correct tolerance and are too thin to anodize (show as silver). Shim design characteristics may affect weight. Weights are accurate to the nearest gram. Shims allow a rider to adjust the ID of a frame for a range of different sized posts.