I would never make a published claim as to brake boss braze on spot dimensions without also specing the brakes and rims too. It is a simple exercise to mock up on paper the actual rim cross section and then the brake as it would be when clamping the rim and from that determine the boss to boss width and the axle to boss height.


Cantis have their pivot below the rim, the pads are above the arm's pivot. Center pulls have their pivots above the rim. Additionally to any post length or diameter differences between the two designs know that the spring's tab/hole/mount can be rather different too. All cantis don't have the same spring hole location as too all centerpulls don't have the same spring hole location.


When I first started this stuff (frame work) I did a lot of test fitting of wheels and brakes on the bikes that I had access to. I made notes on their dimensions and how the resulting set up actually worked. I found a few mms of too this way or that way and the set up would be really good or result in an underperforming brake that had very limited adjustment range.


Regardless of what numbers others say I strongly suggest that you test the advice in real life by a mock up before you start to cut or file any thing. Andy