One of the things I love about my Brompton is how easy it is to wheel when folded (especially with rear rack and EZ wheels), but my one disappointment with my otherwise-beloved Brompton is that the gear range is so limited. So, I'm thinking about the Mezzo, but would like to know - how easy is it to wheel when folded? I see it only has two wheels at the far back of rack. I assume that you have to tilt the bike up to wheel it, no? Would it be possible to add another set of wheels to bring total up to 4 like the Brompton?