The bike has 21k miles on it. I don't suspect wheel bearings because it happens while cruising straight at a steady speed of about 55mph.
Of course I've been fooled before on car noises. I did my own car repairs for 36 yrs until I started contracting away from home. I don't have the time or usually the tools to do many repairs any more. And I haven't ridden bikes all that much especially this Concours which appears to be fairly noisy anyway in the transmission area.
I've got it up for sale too. I don't want to sell it with a serious problem. Right now I'm trying to decide if I want to replace the tires. They are almost slick and I have been riding it to work while it is for sale. I'm liking the bike more and more and the wife was ok with me riding the bike. But, not long after I bought it I managed to drop it on my right foot, break a bone that caused blood clots in my leg, hospital visit, blood thinners, etc. Everything is ok now except for the wife! She's only with me here in FL about half the time, so I get to ride it about half the time! Ha!