I do understand the goal of "centering" forces by joining stuff on centerlines. But when blades go from a 100mm dropout spacing to a crown that is narrower it is hard to keep the caliper mounting bracket on the center of the blades. I'll bend a Willets style bracket to better track along the blade but it isn't on center. I can't say that I see a lot of blade failures that would suggest this is a big issue.

I don't think this really maters. Unless one is REALLY pushing the amount of materials used and thus the structural strength well beyond what is pretty common for builders to work with. Andy.