Purpose and benefit Solves mismatched seatpost and seat tube diameters so you can use your preferred seatpost across different frames without compatibility worries. Eliminates the need to a post or perform permanent frame modifications when swapping components. Provides a secure, slipresistant connection for safe riding and consistent saddle position. Key features Compatibility: available in multiple conversion sizes, including 22.2 to 25.4 mm, 25.4 to 27.2 mm, and other combinations up to 33.9 to 34.9 mm to cover most standard seatpost/tube pairs. Length: 100 mm overall length for ample overlap with both seatpost and seat tube, improving clamping security. Material: made from durable 6061 aluminum alloy for good strength under riding loads while adding minimal weight. Precision machining: accurately bored internal diameter and consistent wall thickness reduce play and prevent slippage during use. Simple installation: slips into the seat tube and accepts the intended seatpost diameter, compatible with standard clamping systems. Performance and reliability Designed to maintain integrity under normal cycling stresses and daily use. The extended 100 mm engagement length plus precise fit minimizes movement and keeps saddle position stable over time. Corrosionresistant aluminum alloy construction offers longlasting performance without adding significant bulk. Typical use scenarios Bike upgrades: fit a preferred aftermarket seatpost into an older frame whose seat tube is larger than the post (for example, using the 22.2 to 25.4 mm reducer when the post is smaller than the tube). Bike swaps and travel: move one seatpost between multiple bikes with different seat tube diameters without carrying several posts or adapters. Dropper or specialty posts: adapt unusual post sizes to standard frames to test fit or temporarily use a specialty post without committing to a frame or post . What to check before buying Confirm the outside diameter of your seatpost and the inside diameter of your seat tube match one of the available conversion pairs (examples include 22.2→25.4 mm, 25.4→27.2 mm, up to 33.9→34.9 mm). Ensure your seatpost clamp allows the additional 100 mm sleeve length and that insertion depth meets your required saddle height. This long reducer sleeve provides a simple, durable way to match seatpost and seat tube sizes, maintaining a secure fit and enabling flexibility across frames without permanent changes.