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 the Chain Checker’s pins into two links, press the swing arm gauge tight and then check the gauge window for an accurate reading.
The Park Tool CC-2 Chain Checker is 9-10-11 speed compatible. For 9 and 10 speed chains, it is recommended to replace the chain at or just before the 0.75% readings. For the 11 speed chain, replace at or just before the 0.50% reading.