pic: Sliding Wheel Chain Tensioners

[MrForbes]

That's a neat idea!

I do see one potential problem with it...since it's a square tube, and there is nothing surrounding the bolt, the tube will crush before you get the bolts tight enough to securely clamp the tube in place so it won't be slid by chain tension under load.

Adding a 3/4" long spacer around each bolt might help.