My old Bianchi Volpe has the original cantilever brakes. What would be a reasonably priced upgrade? It also still has 27" rims on Phil Wood hubs. I've been advised by my LBS that the spoke nipples are questionable and that I need to plan on wheel rebuilds or replacement. Am I correct that I have to stick with 27" wheels because of the brake design or is there a brake option that would allow me to switch to 700 wheels?