I've tried plenty of single speed tensioners on my mountain bikes over the last couple years. All of them have sucked.
Right now I am running a Surly Singlator (which i heard was the best around), It skips quite often, especially when the bike returns to the earth after a bunny hop or something. I had it checked out at the LBS, the chain is the right length, its not like its super long and slack. The chain line is just dandy also. I've got a single speed set up up front, no ramps on the big sprocket.
Does anyone know of a good single speed tensioner that is made for a MTB? It would need to have horizontal adjustability as i am running a single gear on an 8/9 speed hub w/ spacers.
I've seen a few online that looked legit but it appears that they lack the capability to be adjusted side to side to correct the chain line.
budget is $100 or less.
:edit:
by the way this is the bike it's going on