Originally Posted by
garage sale GT
If your bike has vertical dropouts you'll have to buy a singlespeed kit anyway in order to get the chain tensioner, and the kit will come with cogs and spacers.
+1 I recommend getting a single-speed kit even if you do have horizontal dropouts. Cogs for multi-speeders are profiled to allow for easier chain engagement/disengagement. An SS cog will have taller teeth with no ramps which will hold the chain on much better.