I thought I'd post a solution that I have come up with that is cheap and easy. My bike is awesome and dependable, but I've always had chain tensioner problems.I had one go through the rear wheel and wreck me at 30mph!After six different designs and reconfigurations i have finally come up with a good answer to the problem. Find an old STEEL derailer. Put a small bend in the spring loaded arm and mount your tensioner wheel to it.Then, depending on your mount, add a second spring to add more tension. I have mine mounted so you can put a turn in the spring to add tension, or take a turn out for distance riding.Problems solved. My bike runs better and smoother and I can ride in confidance knowing that the tensioner will never slip.Photo attached.Cheers!