Check the listing for details. Paul Component Engineering Chain Keeper 35.0 - Black. Color: Black, Condition: New. Listed at 75.99 USD. CHAIN KEEPER The Chain Keeper is a guide to keep your chain right where it belongs. Mounted in place of a front derailleur, the Chain Keeper works with single chain ring drivetrains using a narrow chain. The chain block surrounds the chain as it meets the chain ring and prevents it from skipping off. TECHNICAL INFORMATIONMaterial6061 AluminumWeight69gFinishAnodizedAnodized ColorBlack, Purple, SilverClamp Size28.6mm, 31.8mm, or 35.0mm ↓Chainline Range34-55mmInstructionsDownload PRODUCT STORY The Chain Keeper clamps on to the seat tube of the frame. The portion of seat tube where the clamp mounts must have a circular profile and a diameter of 35.0mm, (+/-0.5mm). Designed with adjustability in mind, the Chain Keeper can accommodate a range of chainline measurements and chain ring sizes. Note: This is not designed for downhill, freeride, or big hit use.