Park Tool, CC-4, Chain Checker, Compatibility: 5-12 sp. (Inc AXS)
The Park Tool CC-4 Chain Checker is a drop-in style gauge that measures bicycle chain wear. The laser cut CC-4 accurately measures a long section of chain and strategically comes in contact with the chain in three places, quickly and easily taking the guesswork out of determining when chain replacement is necessary. The tool works on any 5 to 12-speed derailleur chain (including SRAM® T-Type, SRAM® Flattop™, and Shimano® XTR® 12-speed chains) and is designed to accurately indicate when a chain reaches 0.5% and 0.75% wear, the points at which most chain manufacturers suggest replacement.
5-to-10-speed chains: replace chain at or just before 0.75%
11-to-12-speed chains: replace at or just before 0.5%
Check with manufacturer for specific replacement instructions