We had a young black lab join a group trip (very rural farm country). It kept darting between bikes and had us all very much on edge. We had a long gravel section and couldn't drop him. He followed us 8 or 9 miles to the place we stopped for lunch. After lunch we tried to sneak out of that little town before the dog noticed us but he saw and followed again. We were now on pavement so we cranked it up. That dog was amazingly game. It stayed with us for another 5 or 6 miles. For the rest of the day --all the way to the motel-- we kept expecting that dog to show up behind us again. He would have been very far from home when we dropped him.