650b no-brainer?
 

Okay, I may be about to embarrass myself, but so be it. I have been toying with the idea of converting my Maruishi to 650b for quite some time, but just got inspired to do the measuring today. Well, genius that I am I went out to measure holding the baby, and thus couldn't do the requisite 320mm from the dropout thing, because I couldn't remove the wheel. Unwilling to return completely empty-handed, I measured the space between the seat stays at the bridge. I figured at least I'll know the 320mm measurement is bigger than that, right? Well... The measurement at the bridge is a cool 63mm. Am I missing something, or does this mean I have some Hetres in my future?

Yes if you've got 63mm at the chainstay bridge you're well on your way.

Some bikes will have clearance issues at the Brake Bridge, but if you've got 63mm at the chainstays it sounds like this frame was made with wider tires in mind.

Sounds like a go.

The seatstay clearance @ 320mm from axle center is almost always greater than the chainstay clearance @ 320mm. So, so far so good, but you really have to take that chainstay measurement. And don't forget the fork blades, either! For Hetres, I recommend a clearance of no less than 46mm @ 320mm from axle center. This will provide ~3mm clearance between the tire and the chainstay. You can get away with less, but then starts getting risky.

Thank you all for talking sense. Nap time chainstay measurement says Cypres, yes; Hetres, no. : )

Quite a bit of difference between 32mm and 42mm tires. If all you're going to get is 650Bx32mm, I'd stick with 700c.

Yeah, the Vittoria Randonneurs in my basement are sounding better all the time. If only they weren't so miserable to put on the bike.