One caution with cantilevers angled down for a smaller rim. As the pads wear, the contact patch moves down. Unless you angle the pads back up, they can slip off the bottom of the brake track. I don't think the pads can reach the spokes, a scenario you never want to see, but just comiong off the rim makes for a real loss of braking power. (My '79 Mooney was designed and built to handle both wheel sizes with the cantis set between. It's been 700c from day one. Mid wear pad adjustments are a fact of life.)