chain whips won't work mon yr cog.. you gotta have the proper one.. some 3/32 stuff will work.. but not that well.. fixed w no brakes isn't really the place for things to be sloppy. thats what u get if u use 3/32 on 1/8 stuff.. lots o slop.

1/8 stuff is nice, cuz its cheap, has bushings on the chains.. making it toughter.. some people with bad chainlines (common on conversions) or who are running road cranks with 3/32 chainrings will go w a 3/32 drive train (chain+chainring+cog) and it's fine.. running a 3/32 chain that's bushingless will quiet a poor chainline, but if u are building from scratch on a true track frame, and if u can afford it.. buy 1/8 if u can.