Since the my daughter and son were infants, we have camped and biked as a family. My partner showed little interest in combining both activities in the form of touring/bike camping, but the kids did. So, I decided to take my daughter, about 7 years old, on a trip. Our first "tour" was a 6 miles ride to a state park campground. I threw a seat post rack and handle bar bag on a bmx, and we were off. My daughter and later her younger brother both loved these outing and this bike in turn. After a couple of trips, I cut the handle bars down to match the width of the kids shoulders. I wish I could have done the same for the really long ,180mm, cranks. A single gear also limited the usefulness of this bike.
Claire and Harris' panniers carry personal clothes and stuffed animals. I always put something important like the lighter, knife or a compass in the handle bar bag to help the kids feel an integral part of our expedition.
Next I purchased 13" framed mountain bike with road tires. The bike fit except the reach along the top tube was a bit long. I solved this by buying the shortest stem I could find which let to buying new handle bars too.
Once the kids started carrying more in their panniers, the seat post rack quit working so well. It took me some time to figure out how to mount a regular rear rack on such a small frame. The trick is the pictured seat post clamp with rack attachment points. I still needed to to buy stock aluminum to fabricate my own mounting stays from the rack to the seat post clamp. 20 minutes with a hacksaw, drill and file and the aluminum became stays. This bike rocks and my son still rides it. I have about $250 total into it.
I added a front rack and bag for the tour above.
Another bike I tried using for a time was this 24" wheeled road bike. I paid $25 dollars for it, cleaned and repacked all the bearings and it worked well except for the limited gear range; kids had a hard time on hills. A triple chain ring is needed for any trips other than railroad grade.
With what I had leaned on previous bikes, it didn't take long to build up this 15" framed freebie my mom didn't use anymore. I cut the bar width, shortened the stem and attached a rack. Fenders and 700c wheels keeps her rolling in wet weather. This will soon get handed down to my son.
This is a bike my friend and I built up for his daughter. A triple Nashbar mountain bike crank, a shortened stem, racks and fenders completed the job. This bike rolls really nicely with 27" wheels and Continental Gator Skin tires.
Kid touring bike don't take much money. Bike fit and function are key to happy campers, and many bikes will work well. Happy trails. Oh yeah, licorice is good on rides too.