Not the OP, but I've got a strange sound coming from my rear wheel area. It's a faint, high pitched, intermittent sound, almost like a small bird cheeping.
At first, it happened seldom and I actually thought I was hearing birds in nearby bushes. Now it's more frequent and can happen in my garage.
I had recently changed my rear brake pads and though there was some alignment or wear-in issue. But the sound happens even if I'm applying the rear brake.
It also occurs when I raise the tire off the pavement and spin the rear wheel by hand, no pedal or chain movement.
I've ridden and serviced bicycles for 70 years and have never heard such a noise.
Wheel bearing? Any ideas??