We had to machine the brake disc mounting surface down because the width of the 390 triples isn't wide enough to fit both calipers in alignment with the wheels. WE also had to grind the spokes of the wheel down to fit without hitting the backs of the calipers.Fantastic Project!!! A real SuperMono!
I'm curious about the wheel & tire change. It looks like once you put the fork-lowers on, the front 690 wheel and tire just drop right in. What did you have to do to get the 690 rear wheel + sprocket + disc to replace the stock 390 components?