So when you run a derailleur, what sort of wheel do you use? I can see now that spacing the rear triangle from 120 to 130mm for a normal road wheel would be a bit of a stretch. Were'nt the older freewheel wheels something like 126mm?

BTW- I'm just asking this because I think a bike with track geometry, bullhorns, TT levers, a single front ring with 5 to 8 gears in the back + a bar-end friction shift would be super fun to try esp. with a frame drilled for a rear brake. I like riding fixed.

Thanks for all the replies.