I'm about ready to make a jig for lining up and holding the cantilever bosses in place while brazing, and I'm having a hard time trying to figure out the exact location I need. I plan on using tektro CR720 cantilever brakes, and 700c rims. It seems I need 283mm from centre of wheel axle to centre of cantilever bosses, and 70-80mm between cantilever boss centres? Can anyone please clarify this for me? Thanks