I saw tensioners for SS.
http://sheldonbrown.com/harris/singl...tml#tensioners
White Industries Fixed/Free Eccentric
http://sheldonbrown.com/harris/fixed-hubs.html ???? can these be used fixed?
"These hubs feature an eccentric axle mount, finally allowing easy conversion of your existing mountain or road bike to singlespeed or fixed gear without the need for kludgy chain tensioners, even if you've got vertical dropouts!"