Function and purpose Aluminum alloy seatpost adapter sleeves that convert seat tube inner diameter to fit a different seatpost size. Use a reducer when your seatpost is smaller than your frame's seat tube so you can install and secure an existing seatpost without replacing it. Available size conversions (inner diameter to seatpost diameter) 22.2 mm to 25.4 mm 25.4 mm to 27.2 mm 25.4 mm to 28.6 mm 27.2 mm to 28.6 mm 27.2 mm to 30.4 mm 27.2 mm to 30.8 mm 27.2 mm to 31.6 mm 27.2 mm to 33.9 mm 31.6 mm to 33.9 mm 33.9 mm to 34.9 mm Key benefits Compatibility: Matches frames that have a seat tube inner diameter equal to the reducer size for a proper, secure fit. Lightweight: Each sleeve weighs approximately 25 g, minimizing added weight while maintaining reliable support. Durability: Made from aluminum alloy to provide strength and longlasting performance without significant bulk. Costeffective: Allows reuse of an existing seatpost instead of buying a post or replacing the frame clamp. Simple installation: Insert the sleeve into the frame's seat tube, then insert and tighten your seatpost — no special tools or modification required. Performance and fit Designed to center and support the seatpost inside the frame tube, preventing wobble and ensuring stable clamping. Suitable for everyday riding across different cycling styles where a precise, stable seatpost connection is required. Typical use scenarios Upgrading or swapping components: You want to use a preferred seatpost that has a different diameter from the bike's seat tube. Travel or rental situations: Quickly adapt a carried seatpost to different bikes without specialized parts. Restoring or mixing parts: Fit a modern seatpost into an older frame, or fit a spare seatpost when an exactsize replacement is not available. Notes for selection and use Choose the reducer whose outer diameter equals your frame's seat tube inner diameter and whose inner diameter matches your seatpost. Ensure proper clamping torque on your seatpost clamp and confirm the sleeve is fully seated before riding. Intended as a mechanical adapter; check fit and function after installation for stability and safety.