Park Tool CC-2 Chain Checker Your shifting has gone to crap. You've spent hours in the garage frantically adjusting your derailleurs like a mad man; and | nothing. You've lost sleep. You finally do fall into slumber only to hear the clicking and clacking of your malfunctioning drivetrain. Well, before you go and make unnecessary drivetrain purchases, we recommend you give the Park Tool CC-2 Chain Checker a try. When it comes to poor shifting and uneven drivetrain wear, manufacturers recommend chain replacement before rear cog replacement. The Park Tool CC-2 Chain Checker lets you quickly and accurately determine the wear and stretch of any chain. 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 CC-2 is 10- and 11-speed compatible. For the modern 9- and 10-speed chains, replace chain at or just before the 0. 75% readings. For an 11-speed chain, replace at or just before the 0. 5% reading. Features Related Articles: WHEN TO REPLACE YOUR WORN CHAIN UPC: 763477001313 Manufacturer's Part No: CC-2 | Park Tool | Cc-2 Chain Checker Cc-2