These threads seem to pop up once every month or two don't they?
I ride alone, mostly at dusk, so I don't see many others out when I'm riding. Yesterday I saw a guy about a mile up the road and made it a point to catch up before I turned around to go home. When I caught up to him, we were in a section where it was too narrow to pass safely at speed. I stayed about 30-45 feet behind him till the path widend. Would you consider this riding someone's wheel? It seems some of you would, I always thought it was basically like tailgating on the highway. Riding inches behind the other bikes wheel.
I don't think it's very safe or polite to stick right on the back of someone without at least making sure they know about it and know how to ride together safely.