the broken warrior
Join Date: May 2004
Bikes: schwinn paramount chrome 1967, bill lewis (his only track bike) 1983, khs flite 2004 (I'm a track head)
I suggest the following. Get something in the front that you can always use, the high 40s is your best bet if your not used to riding a track and skidding. Otherwise you can move into the low 50s, a 50 or 52 is a great front crank.
The rear is what can keep changing. Depending entirely on the power of your legs, I would suggest something around 15 to 17. If you have powerful legs, then a 13 or 14 may be more your style, but it becomes harder to skid and stop if you pair it up with a large enough front crank.
My 2 cents.