pic: Sliding Wheel Chain Tensioners

[MrForbes]

Originally Posted by jblay

is that really a problem because of the fact that all the tightening is happening on the c channel and not the square channel

Yes, it is really a problem. Bolts work best when they are clamping something solidly between them, so they can squeeze the part very tightly. You could try it and see what happens, experiments are a good way to learn the effects of certain design principles.