What can cause bottom bracket loosening? This is an ISIS cartidge BB, Italian threaded, right/drive side "cup" that somehow in normal riding unscrewed almost all the way out. I didn't notice it until my crank moved so far out I couldn't get it into the big ring. Note that the unscrewing motion is opposite the pedaling direction.
Some kind of precessional motion from pedalling?
And how did it unscrew that far without pushing my crank off the spindle?