Originally Posted by
cyclisteaux
FBinNY: Brilliant suggestion, dragging the brakes to simulate hill climbing! Thanks. I'll forward your advice but refrain from calling him a doofus! ;-)
As I hinted, I'm not sure he couldn't think of it as much as he didn't want to bother. Before going back, take some time to simulate it yourself using the brakes. Given the nature of the problem, I suspect that it's somehow related to a deflection under load rahter than bad bearings. Try to get to where you can duplicate it consistently, then maybe rather than having the mechanic ride it, you might have him go outside while you ride by and produce the problem in front of him.