We've been subdivided out of the possibility of letting pets run loose, but when we were out in the country, a friend and I often took our dogs on mountain bike rides of 10-15 miles, and occasionally longer. I live in the Sierra near Reno, with climbs to 8000 feet all around, and the dogs easily kept up on the flats and climbs. We had to wait for them on the downhills, but they enjoyed the rides and usually wanted more.
These were good-sized dogs, a lab cross who could run like a greyhound and a husky mix. No experience with little yappers like Yorkies. Weren't they originally bred to be bait?