Thoughts on the Springer Bicycle Jogger?

 I wouldn't put much weight on him, either. Bean is 13 lbs, at 2 1/2 years old, and her chest didn't come down until she was 14 months. Even the little dogs keep on maturing after a year.

 In the backpack you mean? How much should I put in there then for now?

 All I put in Bean's is my cell phone and keys, and some poop bags, LOL. I haven't ever weighted a dog, so IDK for sure, but I know that bearing extra weight is hard on the joints, just like running on concrete is.

 Hm alright. So maybe I'll just put in a water bottle on each side. One for him and one for me? Have you seen results when using it?

 Bean HATES it, so I haven't used it much. I have to sew some sort of lining into it. I think it's bugging her skin, LOL. She's a bit of a diva!

 I wouldn't put two water bottles on a growing up at ALL- water is heavy! I wouldn't put more than maybe 1/2 pound total in the pack- use baggies or rice or kibble or something.

When Bailey wears his backpack on walks, I put a water bottle in each side(not full, maybe half full each at the most), keys, and poop bags. Its really not that heavy, but I dont want it to be since he is older and there is no point in putting extra weight on his joints, and having to carry the backpack no matter how light it is makes him feel like hes "working".

 Alright thanks guys! Simba is okay once things are put on him like coats in the winter, or his gentle leader. It's just getting it ON him that bugs him. Peanut butter works good for that. :P

 Many of us know how difficult it can be to get sufficient exercise for a pup of his age BUT it still needs to be less rigid than when he is physically mature. Bugsy was an INSANE pup - redefining the term a handful LOL (he still is at nearly 5) we did lots of different things to keep him worked.  Play dates were awesome and lots of fetch, low thrown frisbees, several walks/hikes a day, etc.,  plus of course various training sessions

Trotting with the bike, jogging with him, carrying additional weight or going on the treadmill isn't a great idea until he is physically more mature.  It is my understanding that it has to do with the joints not being completely formed/hardened.  What I was told was it is the constant speed that is not good.

I did get a pack for Bugsy when he was 10-11 mos old but he just carried empty water bottles (to get used to the extra girth and get comfy with it), my phone, his long line and toy if we went to do field work.  Probably never got near 5lbs and he was already 90+lbs.

My understanding is that 10% of their body weight is a reasonable normal carry and a fully grown fit dog can carry up to 25% of their body weight (this has to be worked up to).

The pack should put most of the weight on the upper part of their back/ shoulders

 It really is annoying isn't it? I want to do this stuff with him and I wish I had a backyard so he could burn some of this energy off but I don't. :-/ What if the treadmill is on the lowest setting? Or is it still not a good idea?

Also I need to look for a better pack for him because I looked on petco to see the ratings almost all of them were bad ones. Of course my mom won't listen to me and just return it. *Rolls eyes* 

 I taught Bean to walk on the treadmill as a pup, but never did it for more than 15 minutes. The constant motion is *not* a natural thing for dogs (they stop and sniff, sprint, meander, sniff, scratch, dig a hole, etc, they don't just flat out go 3.2 MPH for however long). You can use it as a training exercise, but I wouldn't run him on it. I'm *very* careful with puppies, ESPECIALLY of unknown origin, because joint issues are often not evident until they are older.

 Oh no I won't run him on it yet, but I think using it as a what you said might be a good idea. I might not even do 15 minutes all at once. Like break it up five minutes here, here and here.

I rollerblade instead of biking so I'm no help on your original question, but I thought that I would second the longline work - it allows for the dog to run as much or as little as they want which is especially good for pups.  I actually just posted some pics from my dogs' regular hike in a local field.  One is off lead, one is dragging a line, and the other is on a line that I hold due to bolting issues.  It's also a great way to work on their recall and I think longline work is the main reason I feel comfortable hiking two of my three off lead now.

 I have tried the long line, he tends to get tangled up in it, which makes running not as fun for him. :-/ Should I try making it shorter or something? I can't remember how many feet I made it.