Folks, I am seeking your advice.
Several months ago, I discovered that my Hollowtech II BB non-drive side bearing was stiff. While the problem was cured by replacing the BB with a new one, I also noticed that the bearing facing surface on the crank spindle was slightly corrded. Cleanning this up seemed to cause no problems, and the new BB was a huge improvement.
Now however, less than 6 months later, the new BB has failed in the same place. The bike has had some reasonable use in this time, but probably less than 500 miles in total.
My question is – is this within normally expected limits for BB bearing wear? Or, could the minimal corrosion (smooth to the touch, no play) on the spindle be letting in enough water to cause corrosion on the BB. In reality, I cannot imagine this last, but cannot be sure.