I was at Clever Cycles in Portland and was so close in getting the Brompton M until it was a little too bumpy on a test ride. I have lower back pain/soreness that is tolerable but I am scared of the bumpiness that might worsen it. I think the upright position is good but is it good enough to counter the bumpiness? Right now I have a fixed gear that I am thinking of converting to single speed (and raising the handlebar is another option but it would look awkward with the frame-style) which I hope can help with my lower back, if not I will forgo the bike, and getting the Brompton might help even more. I am not getting the Brompton solely for this reason. I think it just a really versatile bike.