Originally posted by Hot Pepper
If one cup that loosens in the direction of crank rotation is bad, then both doing so must be twice as bad! As in English bottom brackets!
No, english bottom brackets are so they will both tighten when pedaling, yes?
At least every single report i've read of an Italian BB coming loose it is the right one that loosens. And on an english BB its the right one that is reverse threaded.
If you read my statement, I said one side will loosen with pedaling, not which side would do so or any detail on exactly how that occurs. My guess is that the bearings involved reverse the thrust so that, counter intuitively, the cups will tend to be loosened in the opposite direction of the crank rotation. However, i know none of this for sure, only that the right cup tends to loosen up on an italian BB.
thanks,
Steve