I felt a few rumbles before and during a nice 123 mile day I think. I think at least 3 were boke by then. A few days later I noticed the wheel top was going sideways, worse when leaning. It seemed OK when just spinning it and went out 3 more times, 20 miles. So I was also wondering if the axel was broke. The last ride it was getting really wonky when not straight up, still rideable. The magnet sucked up the bits, so it was still smooth. There wasn't a speck of grease on it.