Originally Posted by pyze-guy
That tensoner adjusts in/out. You should be able to move it when you shift the chain easily. I'm not sure a pulley wheel will work. Seems to be a square edge where the wheel is in the pic, pulley wheels are round. Best bet is to check lbs for one and go from there. Keeping my 7 speed deraileur for wifes bike if I ever build one for her.
It does adjust in and out but I don't want to have to dig up an allen key every time I want to change gears. I made a diagram of how it works. That square edge doesn't really serve a purpose other than giving you something to stick a wrench on if you want to seriously overtension the bolt (number 1 on the diagram). I think all I have to do is insert an extra pulley next to where the original one is. If I got a replacement set of pulleys I'd be able to ditch the cheap pulley that came with it and have 2 good quality with bearings instead.
1. allen bolt
2. cheap plastic pulley and metal seals (no bearings)
3. chain guide
4. female threaded spindle
5. allen bolt
6. tensioner arm
7. spring and attachment hardware