I have been thinking about getting new tires for the Birdy for a while. The Mrs always rolls away from me downhill on her Moulton TSR with Schwalbe Stelvio tires, and from what I can see most people think these tires are significantly faster than the stock Maxxis Birdy tires.

So, I got a pair of Stelvios, 18x1 1/8 with a wire bead. They are very small - you will want to get matching inner tubes, as the stock 18x1.5 tubes are bigger than the tires and were very hard to fit! I'm sure someone will be curious about weight - my kitchen scale says the Stelvios were 220g, v.s. the Maxxis at 350g. That's a weight reduction of 260g (0.6 lbs) for two tires, which is of course quite trivial in any real sense - though it sounds more impressive as a 37% reduction!

There's been a lot of rain, so I haven't had a chance to go for any long rides yet. My first impression is that ride quality isn't noticably worse, which I had expected with a much narrower tire at 120 psi rather than a wide tire at 90 psi. The Stelvios are much smaller than the Maxxis, and so gearing is definitely affected. I'll have to do a rollout measurement to find how much, but my feeling is that I'll more than ever think the bike is geared a little low. Oh well, if the tour we keep thinking about ever happens I'll be better equiped for hill climbing with a load ;-)