We’ve been seeing a lot of bikes with the idler drive system set up incorrectly. Please take note of the following information:
When set up correctly, the drive side, where the chain is routed underneath the idler, should run on the inside. The return side, where the chain is routed over the idler, is on the outside. Also, the chain keeper bracket should be set up with the longer section across the top of the idler wheel.
See pictures below:
When routed incorrectly, you may experience shifting problems; while riding under extreme riding conditions may cause damage to the post where the idler is attached, due to increased leverage on this area of the frame.
To avoid these risks, it is imperative that your idler drive system is routed correctly.