Park Tool Chain Wear Indicator

The Park Tool gauge makes it easy to measure chain wear. It has a longer design, which means it measures across more links and ensures a reliable result. It is suitable for 5–12-speed chains, with the exception of SRAM Flattop and T-Type. A 5–10-speed chain should be replaced when wear is at or just before 0.75%, while an 11–12-speed chain should be replaced at or just before 0.5%. A worn chain negatively affects shifting and gradually damages the cassette and chainrings. The Park Tool gauge will show you when it's time to replace your chain.