This is just out of interest but what size tyres do most of you run on? Inspired by Charles' example, idle curiosity, and the need to buy something new for the bike, a few weeks ago I thought I'd sample some (700x) 20c tyres. I guess I've clocked up about 700km on them now and they're quite nice and light, and nice on the ascents. On the descents though they really feel delicate and if there are grooves in the road (as on the descent from Tomin or, the new TCC fave, Kazahiri) then they strike me as a little bit precarious, and requiring some care. Granted it could be just the tyres themselves (panaracer stradius elite lite - these were pretty cheap at about 4000 yen each, so I thought they would make a good sample batch) and some other commentators have noted that these could be a bit dicey on descents (review here), but it got me wondering a little about tyre size. It is, after all, only 3mm. Prior to this I was on 23C and I'm now thinking of a return.