Floatin tensioner and scooter band brakes?

Hi all. I am starting my first build with a Felt twin. I have already picked out engine, mounts, accessories and some other bits (Justin of Pirate Cycles was a BIG help) but I am left with wanting to upgrade the brakes and the chain tensioner.

Has anyone ever tried a floating tensioner? I ran a couple of searches with no hits.
McMaster-Carr page number 1022 (sorry cant post links yet)
If you have used one which size worked with the 415 chains?


I am also thinking about throwing a scooter band brake on the front wheel.

This would be mounted outside of the fork on an extended axle. I found a local place that will cut me a longer axle and I can mount it to the fork with a collar clamp. Does anyone have experience with this outside of the Grubee rear wheel or Shimano kits?

Cost is all relative. I dropped over $500 on a bicycle. $50 for a chain tensioner looks like a bargain compared to the Ridley. I am coming at this hobby from the motorcycle world so everything stills looks inexpensive to me. I know people who spent more money on their gas caps than I spent on my engine kit.

The concept itself is pretty simple. I don't see why I couldn't build a version of this for under $20. McMaster even sells the UHMW polyethylene in tube and channel form. You could also build these with rollers.