Park Tool CC-2 Chain Checker

To alleviate poor shifting and uneven drive train wear, manufacturers recommend chain replacement before rear cog replacement. Now you can quickly and accurately determine the wear and stretch of any chain with the Park Tool Chain Checker. Simply insert t Compatible with all bicycle chains For modern 9 and 10 speed chains, replace chain at or just before the 0.75% readings For 11 speed chains, replace at or just before the 0.5% reading