Thats a valid concern. Its a bit on the sluggish side for a commuter.
wanna buy my '08 Raleigh One-Way frame? Its versatile as heck, actually meets all of your requirements...it might fit 42's.... but I don't remember the spacing.
I'm in the middle of a similar build actually. I'm using an Austro Daimler Inter 10, gonna do a 7speed IGH commuter with a coaster brake. I'm only gonna be running 30mm tires though
I thought the Polyvalent Build Kit came with 650's?
Originally Posted by www.velo-orange.com
Wheel size is 650b, which we feel is really the best choice for a comfortable ride on bumpy city streets. Maximum tire size with fenders is around 44mm and around 55mm without, but the frame handles best with a tire around 38mm wide.
of course if you're going the 650B route that opens up some option for other vintage frames that would otherwise not take as wide a tire as you wanted.