Hi there, I'm putting together a Soma Buena Vista (size 50cm in graphite) for my wife.
She test rode a few sizes last weekend and the 50cm is the right fit for her. The bike she rode was built up with a 700c wheelset and there was a lot of opportunity for toe overlap at the front wheel. I was thinking of building it up for her with a 650b wheelset to get a little extra space and wanted to see if there was anything special i should look out for if i do that. (the frame is spec'd for 700c wheels.)
Outside of using a long reach brake i can't think of much off the top of my head, but I've always built using the "recommended" wheel size. I've found a couple of Buena Vista frames built up with 650b here:
This one's super-nice
And another; also very nice
The test ride(s) were "to kill some time," while we happened to be near the shop. It's for her birthday which is in a couple of months, (and I'm doing it on the down-low, so don't tell her)