Accurate. Reliable. Chain Wear Made Simple.

A worn chain leads to poor shifting and premature drivetrain wear. The Park Tool CC-4.2 Chain Checker takes the guesswork out of chain maintenance with its precise, laser-cut, drop-in design. Measuring a long section of chain at three contact points, it accurately indicates wear at 0.5%, 0.75%, and 1.0%—the key thresholds for replacement. Compatible with all 5–13-speed derailleur chains (including SRAM® T-Type, SRAM® Flattop™, Shimano® XTR® 12-speed, and Campagnolo® Ekar™ 13-speed) as well as single-speed chains, the CC-4.2 is the reliable tool every mechanic needs to extend drivetrain life.

• Two-sprocket (single-speed) chains: replace chain at or just before 1.0%
• 5-to-10-speed chains: replace chain at or just before 0.75%
• 11-to-13-speed chains: replace at or just before 0.5%
  

NOTE: Many drivetrain manufacturers have unique recommendations specific to their components. Always double-check to be sure.