With all due respect, I am not sure how meaningful the test with virtually no load on the BB (i.e. rear wheel in the air) will be.
I notice that my BB is much noisier under load (i.e when the engine is pulling the car along) than when I ease my foot off the throttle and the BB is just rolling.
I also assume that noise is related to friction, which in turn is related to the heating effect of the internals. Hence again, it may get considerably hotter when under under normal load.
