dumb question, but I have to ask: Will a fixed cog screw in on the freewheel side of a flip/flop hub? If so, my brand new 17t 1/8th EAI cog from Benscycle is having the same problem as people above. Formula hub.

edit: i'm not trying to run a fixed cog on the freewheel side, i just wanted to test if my cog would screw in smoothly.