Does the tensioner do a good job of keeping the chain tight? I read on another forum that the chain can still bounce around with a spring loaded tensioner. I figured that wouln't be a problem with a chainguide
my tensioner held real well. i had the spring totally cranked, and the tensioner was literally almost stuck in place. some folks like to run the tensioner on top of the chainstay, upside down to make sure its tight. what i ended up doing was putting the tensioner on in such a way that when there was no chain on, it was practically pointing itself away from the fork. when i put the chain on, it would end up pointing toward the fork - so it was really cranked tight. once i had it set up like this, the chain never popped off - and i took that bike (crappy little fork and all) to the sourlands, chimney rock, ramapo, and skyline drive.
i think if you just put the tensioner on as-is and leave the spring loose, you'll have the thing bounce all over and the chain will pop. i also cut some old tubes up and wrapped them around the chainstay to make a bumper of sorts. that way the tensioner wouldn't hit the chainstay directly, and also couldn't 'bounce' in too much. once i did that, the chain never popped. you can see the tubes in the pic - the little black patch on the chainstay. i kept the tube wrap on with some cable ties.