I know everyone says they train their dogs and I don't doubt it.
You simply cannot train out instinct, though. Think about the 2 incidents below when your dog is
tethered and is put into an unwanted/threatening situation, what will your dog do? Other people are careless, e.g. no control on- or off-leash so you
will be put into similar situations.
I used the walky-dog thing on a bike some years ago. (In fact, if you want it, PM your full mailing address and I'll send it to you even though I do not recommend this.)
We had 2 dogs. Our civilized dog, Jacob, hated the thing. He was pit/hound mix, 50ish lbs, very athletic. He would trot alongside me, we would never go faster than a quick walk/slow trot. He'd frequently pull away as if something on the bike scared him. The spring in the walky-dog helped with that. It was clear he just did not enjoy it, so I stopped with him after maybe 5 rides.
Our other dog, Rudy, was a 45lb pittie, 10 lbs of head and all muscle. Rudy loved the walky-dog! We'd ride our neighborhood most days, then 2 things happened:
- An off-leash dog came after us, we couldn't outrun/outride it. The dog nipped Rudy's rear end, at which point Rudy stopped so I (promptly/unexpectedly) stopped. The dog came at us, and Rudy chomped down on that dog's head. The sound the other dog made was nothing I ever want to hear again, but I calmly told Rudy to leave it and he let go. The other dog's owner was very apologetic, which is great and all...
- A few weeks later, we were riding and a woman had a large dog on one of those retractable leashes. Her dog came at us, she did not have control due to the length of the leash/size of dog. As the dog got near, Rudy went in for the kill. Unfortunately that meant he put his snout through the spokes of my front wheel, which pinned his head to the fork, which brought me to a rather abrupt stop. I went face-first into the road, unconscious for a few seconds. Severe concussion, broken wrist, stitches in my forehead, still have scars on arms and legs and right side of my face. Rudy broke a tooth.
And not that you asked, but based solely on my experience, this is not something I'd advise anyone to do, period. Again, when your dog is tethered and not doing it's job, behavior is altered.