Can you provide a little more information about the problem and the e-bike in question? The reason I ask is I have had the chain come off on my Cannondale Mavaro that has a mid-drive Bosch Active Line Plus system. The chain came off the front chain ring and I had to remove the chain guard to put it back on. What is the model bike and what is the drive unit? Can you provide more information about the replacement chainring that was put on? Thank you!