I was at Academy a while back, and they had this weird little gadget that I didn't know what it was. Got to looking, and it's a temporary top bar that goes on a step-through frame just so it can be carried on a rack.

I don't see it on Academy's site, but here's one with a little video of how it's used:
http://www.amazon.com/Allen-Tension-.../dp/B000ELSSZE

Maybe there's some better way to work things, but that would be one option. I haven't used it, just saw it.