ParkTool® CC-4 | Chain Checker

A worn chain shifts poorly and wears sprockets at an accelerated rate. The
CC-4 is a “go-no-go” gauge designed to indicate when a chain accurately reaches 0.5% and 0.75% wear, the points at which most manufacturers
suggest replacement (contact the chain manufacturer for specific
replacement recommendations).
INSTRUCTIONS:
1. Lower the CC-4 onto the chain while keeping the gauge tip above the
chain (Figure 1).
2. Apply and maintain tension on the chain at the location shown in Figure
2. Note: It is crucial to maintain pressure on the chain in order to obtain an
accurate reading.
3. While maintaining tension on the chain, push the chain onto the gauge tip
to determine if the chain is worn