listen to this, i thought it would be a great idea to let my dog pull me while im on my bike. Well 3 miles later he cut his paws up. Next time ill get him on the grass! Anyway a bike seems like a good idea to me. Idk im a newb lolDon't drag on a sidewalk. You want something with some give for the pup to dig its toes into. Go use an empty field somewhere. As for what to drag, anything you aren't too attached to, because dragging on the ground wears stuff down. You can use lengths of chain, old window weights, round weights from barbell sets. Get creative. Make sure its not too terribly light, though, because I've had light stuff "catch" and then bounce back up towards my dog when she was a puppy.