The Rohloff Caliber 2 is a precision made chain wear indicator which allows the measurement of chain wear to be accurately assessed in seconds. The results show the user whether chain replacement is necessary regardless of whether aluminium or steel sprockets are in use. After extended use, a chain will no longer fit correctly within the sprocket teeth, due to elongation and wear. Correct use of the 'Caliber 2' will ensure chainrings and sprockets are not prematurely damaged, and thus hinder the chain ratcheting over sprockets and causing the cyclist to lose drive.