Originally Posted by
BeardofZaius
I think you're on the right track. Given I can't detect the problem just spinning the wheel and braking, I reckon it requires force/speed of actually being in motion to jog the brakes enough too make the noise. The brakes seem pretty solidly put together too.
The seam in the rim is detectable but quite slight, and very similar on both sides of the wheel though so if it is this, I doubt it will sound much different if I flip the wheel. I'll have a bash at it with a file though, and see if this improves things.
The idea of reversing the wheel wasn't to solve the problem (though it often does on fronts) but as a diagnostic tool to verify that it's related to the rough joint. Even if the joint is off on both sides, reversing the wheel changes how the shoe passes over it. Picture the difference sliding something up vs. down a shingled roof, or rubbing your hand up in either direction over a cheese grater to see the point.
Once you've decided it is the rim joint, hang the bike, gently apply the brake, and rotate the wheel back and forth passing the seam through the shoes and look for movement on the arms, or feeling if it snags.