Join Date: Aug 2009
Location: Washington, the state
If you can feel a rumble, replace the bearings.
I'd suggest even less than a rumble. The slightest roughness or notchiness means that the bearings are living on borrowed time. Red rust dust coming out of the internals of the bearing is another sign that the bearings are near failure, or any looseness including a side-to-side wobble. Pry the brake pads away from the disc so they don't touch, and use that finger on the axle hunting for any slight roughness.
"Older people who are reasonable, good-tempered, and gracious will bear aging well. Those who are mean-spirited and irritable will be unhappy at every period of their lives.
"Let each of use properly whatever strengths he has and strive to use them well. If he does this, he will never find himself lacking."
Marcus Tullius Cicero