I have a '20 700ST that has about 300 miles, I didn't ride it all last year because of back issues. Anyway, I'm getting a very loud harmonic sound from my rear wheel. It happens all the time when rolling. Doesn't matter if I'm pedaling or coasting, and doesn't matter what PA I'm in. The faster I go the louder it gets. If I'm on a bike/hike trail and I'm approaching a walker they will turn around to see what's coming if I'm 50/75' away. I rode 17 miles today and everything worked fine. I stopped a couple times to check for heat, cool as can be. Nothing rubbing or loose, and it's not the brake. I read all the posts about noise and some sounded like my issue but no one had an answer. The last was a while ago so I thought I'd try again. Thanks in advance for your help.