The problem with rolling folded Dahons is that the design strategy was to keep the bike folded (magnets). That’s the wrong strategy in my opinion. A better strategy is to find a way to keep it from unfolding. I know that doesn’t sound like much of a difference, but it is. When rolled over anything but the smoothest surfaces in a straight line, the magnets are simply not strong enough to counteract the bike’s tendency to want to unfold. I’ve had much better success by attaching a hook on one fork and a ring on the opposite one, just above where the magnets are (I used elastic hair bands, cut and tied to attach them) and latching them together. Result: I can fold the bike with handlebar remaining up to use as a handle and roll it with total confidence that it will stay folded - world of difference. I’ve since made it even easier by installing a superb Pletscher double kickstand (thank you thorusa.com). Now I leave the seat post up instead of the handlebar and use a rubberized wire tie (search for “gear ties”) wrapped around main tube and rear fork just behind seat post - even more convenient - no bending - and using the seat post as a handle makes the whole package much narrower. I can easily rest the bike down on the double kickstand (if you were to leave the seat post up but don’t have a double kickstand, the bike would rest on its front crank when set down - ouch!)

[EDIT: Just want to add - there is no reason to try to obtain a tight closure, which is what the magnets are supposed to do. In fact, the bike rolls better with a little space and flexibility between the wheels, which you can achieve with the methods I've described (attach the hook and ring with just enough elastic to allow the wheels to separate a little, or wrap the gear tie around the frame relatively loosely if using second method.]