Originally Posted by
ehcoplex
OK, personally I find it bothersome when thread responses suggest things an OP specifically says they're not interested in.... but I'm going to do it anyway. Reconsider a 650B conversion! The dearth of decent, ready-made rim brake 650B wheel sets could be seen as an opportunity to learn to build wheels- at least that's how I finally ended up looking at it, and I'm glad I did (building wheels is kinda fun, in a tedious sort of way..).
I have considered learning to build wheels and do it myself, but when I start adding up all the tools needed, it doesn't take a long time before it doesn't really make a lot of sense financially. I think if I did that, it'd be because I want to learn (which I kind of do). As for brakes, my Sirrus' brake bridge is sooooo close to the wheel, I would probably be able to get away with some normal long reach calipers without issue. I may very well change my mind on the 650B conversion, since the vintage market where I live (Logan Utah) isn't particularly great.
If I can (barely) fit a 700x25 tire now, what would be your guess as to what size 650B tire I could fit in its place? The math suggests I could go as large as 45mm if the frame allowed the width, but I don't know if my math is right.