Originally Posted by
In Absentia
With a track cog, it's going to be 42 mm. The only way around it is to buy a bottom bracket with a 107 mm spindle and mount the chainring on the inside position on the cranks.
Of course that's not the only way. You could re-space and re-dish the wheel too.
I could be wrong, but couldn't you also just get a bottom bracket with a spindle length that resulted in a good chain line with the chainring on the outside?