The park tool cc 32 chain wear indicator is a useful tool that allows you to find out how worn your chain is before you need to change it a worn chain not only shifts poorly and wears down sprockets at an accelerated rate but it also causes damage to other components of the drive chain to use the cc 32 chain wear indicator simply insert the tool into the top of the chain and read the measurement if the chain reaches between 075 and 05 then the chain is worn or beginning to reach its e