I just started running my dog with me.Of course he was trained to be controled by voice first and we walked all the trails that we ride first several times. He is only 7 months old and can do 8 miles loving every minute of it. There is no other way to get them that kind of exercise and and fun. It’s what they are born to do. Read " Off Leash " Bike Mag, Aug 2010. I do agree that it’s not right for all dogs, but a well trained, properly socialized dog has no problems. My dog has only been on 3 rides so far the third being a 4 man group ride. The group had no problems with him. Happy trails.