This shim will let you easily fit the 27.2mm Dual-Position Seatpost or ShockStop Seatpost into your larger seat tube. Just drop the shim in your frame's seat tube and insert the seatpost. Once installed, the shim is essentially invisible.
Details:• Fits 28.6, 29.8, 30.0, 30.4, 30.9, 31.6, and 31.8mm outer diameter
• Fits 27.2mm inner diameter
• 100mm (4-inch) length spreads out clamping load along seatpost and frame