I’ve been running my 16 week old GSD next to my bike, is this suitable exercise for a puppy?

Forgive me if this question has been answered on your web site - I couldn't find it.

I have a 16 week old German Shepherd from German working lines. I have trained her to ride beside my bike (at a pretty slow pace). She seems to enjoy the experience, but now I have heard conflicting advice on whether it is hard on her hips and according to some I could cripple her by putting stress on her growing joints. Her vet didn't have an opinion. We only ride for about 20 minutes (at a time) twice a day and it doesn't seem to wear her out. In fact when we get back home she want to play fetch and run around the yard. We both enjoy the ride and she looks forward to this part of her day, even to the point of getting her leash and bringing it to me and then doing the doggy happy dance. She is not lacking attention as I am with her all day everyday. Her only quiet time is when I put her in her crate when I need a nap.

She doesn't pull at the leash and we typically run in alleys, which in our neighborhood are grass and not concrete. The bike also enables me to "walk" her at a a brisker pace than I am able to maintain otherwise.

I am sending you a picture of my little troublemaker. Thank you so much for taking the time to read my concerns.

Barbara