Often the owner of an active dog sees the DoggerJogger for the first time and says, “I love it, it looks great, but it would never work for MY dog.” After a demonstration and an explanation they will try it, sometimes with trepidation. But once they get on their bike and encourage their dog, the typical outburst is “This is AMAZING!”
Yes, it IS amazing, but at DoggerJogger we are not surprised because we understand the physics of the bike dog leash. The ability for anybody to ride a bike with an exuberant dog jogging safely alongside seems incredible. However, if you take one look at the numbers you can come to terms with how much easier it is to ride a bike with your dog than to go for a walk.
We asked Brian Leopold, a DoggerJogger owner and physics professor, to explain the commanding strength of the DoggerJogger and why the dog can’t stop the bike. He said, “The work done by the dog if he is going to stop the bike, rider and himself (‘the system’ in physics language) must be equal to the kinetic energy of the system.” Translated from physics-speak to everyday language, he said that the dog can’t stop himself, the bike and the rider unless the dog is able to impart an equal amount of force. If a person who weighs 150 lbs. is going 7 mph on a 25-pound bicycle, a 70-pound dog would have to instantly impart 400 pounds of force! The same setup at 12 mph would require 1,200 pounds of force!
There are several reasons this would never happen with the DoggerJogger, the first being that the safety breakaway has a maximum setting of about 135 lbs. tensile strength, so the injury prevention mechanism would give way before the dog could jerk the bike to a stop. (Even the Heavy Duty HD accessory breakaway has a tensile strength of only 200 lbs, not even close to 400!) The second reason it can’t happen is that the bare feet of any dog running at 7 mph cannot hold against that type of force. Third, the dog’s strongest legs for pushing are in the back, and are designed to push forward. Again, a dog can’t just “put on the brakes,” no matter how strong a puller it may be.