I see a lot about these little guys. I was thinking that a derailer on a bike with gears has a spring loaded tensioner that moves up and down keeping tension on the chain that has to move over the freewheel. Why couldn't one of those be used for a tensioner. It would keep the chain taught and in place because it has a covered area the chain has to go through. I put on on a recumbent midway on the frame to keep tension and it works great. No chain flop and moves with the changing of the gears etc. Get one with enough strength or tighten it and I think it would work great. They have ability for side movement also. just a thought, may not work on engine power. I may try it.