I've seen a Strida in person, though, and I like them better than any of the other folding bicycles I've tried, in terms of actually being able to fold the thing up and unfold it relatively quickly.

What exactly is the problem with the kevlar drive belt? It isn't as if it's a flat belt or anything.

Alas, I'll still have to be fitter before I can carry 10kg up or down a flight of stairs, but more stations are getting escalators and lifts.