Max size Conti do the 4000s in 650c is 23mm which is too narrow.
Ah, good point. Mind you, for tiny people 23mm is enoooooormous. 23mm tyres actually look pretty fat on a 650c wheel I reckon. But if you want wider, then I'd agree 26" is a better choice.
Max size Conti do the 4000s in 650c is 23mm which is too narrow.
26" definitely seems to have more choice than 650c (which seems to have almost died out).
It's frustrating that the 3 small Isens don't take 650b as that with the new 28mm GP 5000 would be ideal!