I fitted Stelvios last night, can't wait to go for a ride! I would have taken the Birdy to work today, but the forecast was for rain. They were quite challenging to fit, very tight on the rim - and I really shouldn't have been a cheapskate and reused my original 18x1.5 tubes, they're bigger than the tires! My only concern with the Stelvios is that they'll lower the already low top gear still further... I haven't measured, but they're visibly much smaller than the Maxxis.

On an unrelated note: my chain keeps falling off at the rear when I fold. That happened every time at first, but then I seemed to solve it by folding fast. I don't think I'm doing anything different now, but the last few times the chain has come off every single time. Could the chain be too long? This may well be my lack of practice, rather than a technical problem, but any advice much appreciated.