Paul Component Chain KeeperThe 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 chainring and prevents it from skipping off.The Chain Keeper clamps on to the seat tube of the frame. Designed with adjustability in mind, the Chain Keeper can accommodate a range of chain-line measurements and chainring sizesBlack69g35.0