Current setup is 46x17. I can climb any hill in this, unless it is 5 mile/8% grade. Note, I am in the hilly portion of WI, it is the land of monster rollers. Group rides are done with 48x17, but I am toast afterwards, and its hard on the knees.

I had a track frame setup with 53x16 as a fixed gear TT bike. Complete with aerobars, SPD-SL's, and a front brake. I could ride it around, but it was intended for the 27-29 mph speeds (100-110 rpm) encountered in a 40k TT. Very hard to stop brakeless from 30+ mph.

Those who say they ride 54-13 or similar are high on the bull-#$%^ meter. It does look bad ass though!

Cheers~