I put my Trek 820 on a stand today. When I turned the pedals and got the rear wheel spinning I noticed that the rear gears wobble as a unit. This would be in coast mode - that is, the wheel is spinning but the gears are not. They wobble at a much slower rate than the wheel spins. In fact, the wobble rate is very slow, while I had the wheel spinning at a pretty good rate.
The bike is about a year old and is in good shape. I don't imagine this is anything out of the usual. Just wondering if anyone else has noticed anything like this.