cog question

[pembo6]

Hi. I am totally new to the whole fixie thing. I have a very newb question.

If I buy a flip-flop hub/wheel, wot sort of cog do I need? Will a 'track' cog work? I need 17 teeth. Or are standard track cogs the wrong size for a fixed side of the flipiflop hub?

Also, do I need a special size lockring. My understanding is that the fixed side has 2 different size threads. 1 for the cog and 1 for the lockring?? Is the cog thread the same size as the freewheel side? And then the lockring thread is smaller?

I don't want to end up with the wrong size cog or lockring when I buy onine.

Thanks for your help.

[BRLVR.v2]

Ignore the proprietary Surly references and it's all the same. http://surlybikes.com/uploads/downloads ... .16.05.pdf

Also read everything in this http://sheldonbrown.com/fixed.html