Well you could always go old school...... Get a cart frame, put some hook rings on the front of it and have dogs pull the cart. I have 2 American bulldogs (which are genetically programed to like pulling) With me on roller blades I can hit speeds up to 25 miles per hour. I stopped doing it though because one of my pups doesnt pay attention and will keep going no matter what. One day he caused me to fall at about 20 miles per hour and i sprained my wrist, ankle, shreaded my right arm and knee, and lost a chunk of flesh off my finger. Its still pretty fun. Once I get a cart with a good roll cage I will most likely get into again.