Originally Posted by
Camilo
The front brake won't open far enough for anything larger than ~35-38mm and even that has to be forced through. The fork doesn't allow the brake arms to open any further. I built up a similar bike for my wife based on a Cannondale cross frame and fork. Hers has canti brakes and has the same issue.
Have you tried deflating the front tire enough to get the wheel on, then re-inflating?
I can usually force a 33mm tire through my open canti, but anything wider requires deflation.