My 4 year old does a 6 mile trip with a small stop @ the 1/2 way point 3 to 4 times a week. Of course we give him a refuel @ the 1/2 way point but it is @ a park and we also play hide and go seek. He also does a 4 mile ride at a faster pace. When we do the shorter ride we go close to the park where there is a walk/fishing/playground/dog walk/exercise type park that has a 1/4 mile paved loop and 2 different 1/16 mileish offroad sections that are technical but wide enough to be fast and my wife and I take turns sprinting the loop and trails while he does a little fishing! To be honest I love this area for that reason alone!!!