Chain Checker

A worn chain shifts poorly and wears sprockets at an accelerated rate. The Chain Checker is a go/no-go gauge designed to accurately indicate when a chain reaches 0.25%, 0.5%, 0.75% and 1.0% "stretch," the points at which most chain manufacturers suggest replacement. For 9 and 10-speed chains, replace chain just as the gauge fits the 0.75% side fits flat into the chain. For 11 and 12-speed chain, replace as the 0.5% side fits