Hi,

I've got a 10+ year old Orbea Aletta triathlon bike I've converted to single speed.
It's got a 58t chainring and 13t cog. I'm using the 3/32" dura ace chain with a tensioner but the chain comes off.
I've tried a half link 3/32" but it will not fit the chain. The bike was 2x10 shifting. I use a zip tie to pull the tensioner and chain into the chainstay to make it work.
It works for awhile and eventually snaps under tension because I don't play around when riding hills and whatnot.

Any suggestions on how to get it to work better? I'd rather go fixed but slightly less aggressive gear ratio.

Also, looking into getting a mountain bike or cyclocross bike to run fixed. Does anyone have recommendations?
I'm over 200 lbs if that's relevant as to frame selection, etc...

Thanks!