Originally Posted by Gramps
Unless the bearings are really shot, you're probably not going to feel them going bad by spinning the wheel. Can't really hear them either with the chain and such.
Best is to spin them by hand and feel for any grittyness, or looseness.
I've never had a wheel bearing disintegrate on me, but I have caught several sets going bad while changing tires.
This is a first for me also on a motorcycle. I have replaced a few wheel bearings during wheel changes (mostly dirt bikes) usually because I could see that the seal was compromised. On cars the bearing usually makes a howling sound for a hundred miles or more before doing any damage or causing any grief. This incident was like getting struck by lightning - basically a sound resembling a light chain slap (which it probably was because of mis-alignment), and then complete loss of rear wheel directionality (very much like a blowout).
I did look at the bearings when I swapped tires last time to see if the seals were OK, and they were. I doubt I could have stopped this incident from happening with any reasonable maintenance process. Who expects a catastrophic wheel bearing event at 6K miles?