Oh, wow! That's really deluxe! I meant like this
These are made for bicycle derailers, but should work for other uses on MABs, if no heavy load is applied on them (not sure if they can handle pedal starting).
Carmichael Sealed Pulleys
SRAM and Performance/Nashbar also offer some. They are usually $15-30 for a pair and will last forever on a bike. I had some on a road race bicycle and they did speed it up a couple mph, by less friction. They never squeaked or went dry either.
Originally Posted by Scootmeister
Hi Rustycase. Tensioners have been an issue since motorized bicycles entered the scene. The problem is not with the theory, it's with the way kit tensioners are designed. Anything mounted to the frame that can rotate is a problem, it's just not going to stay in place. I have a Yamaha enduro with a factory installed chain tensioner that works great, but it's designed so it cannot move and get in the way of spokes and other moving parts. As HappyCheapSkate points out, the solution is to come up with a custom design that fits your bike. The pivot point needs to be stationary, and alignment needs to be correct. You can experiment with the length of the pivot arm and the strength of the tension spring to minimize drag while keeping the chain tight. Here are a couple I designed for my Stiletto bobber. The Giant Stiletto came with a 7-speed hub, so the rear wheel is not adjustable making a tensioner necessary. I used the derailler's threaded pivot hole as the pivot point for the tensioner and used a kit-supplied roller with bearng. On the front tensioner, I used the wheel off of the derailler. If it starts to wear I will switch to a bearing set-up. As Happy suggested, I used steel or aluminum strap for the pivot arm. I hope this helps.