Chain Line Checker

Chain Line Checker is a tool to check the alignment between the front and rear chainlines for a single speed bike. Regardless of the quality of the chainring, the misalignment causes the chain to run diagonally, resulting in increased friction, power loss, accelerated wear on drivetrain and noise. The correct chainline maximizes performance and potentially helps beat your personal best!  So, it’s important to check the chainline!

The tool has 2 different sized grooves, one for 1/8 (thick) and one for 3/32 (thin). Use either side depending on the width of your chainring.

Size :  For 1/8" and 3/32" chainring
Material : Aluminum

How To Use
① Remove the chain and make sure that the chainring and rear sprocket are securely installed.  Then, turn the bike upside down.
② Fit the groove on Chain Line Checker over the chainring teeth.
③ Look at the sprocket on the other side through the upper groove on Chain Line Checker.
*Position your eye directly in line with the groove so that the far end of the groove is perfectly centered in your vision.
④ Depending on how the sprocket appears, the front and rear chainline alignment can be examined.

If the front and rear chainlines are exactly the same, the rear sprocket appears in the exact middle of Chain Line Checker. 

If the front and rear chainlines don’t match up, the rear sprocket won’t sit in the middle of the Chain Line Checker.  The chainline needs to be adjusted.

The chainline can be adjusted by adding BB spacer BC1.37 or Crank Spacer DIA24 (sold separately).