There were two things I made sure of before letting my son carry a backpack instead of a daypack on our family backpacking trips: that he was ready and eager to do it, and that the pack I gave him fit him. The first question I let him answer: I waited until he asked to carry a backpack. (He was nine-and-a-half the first time. Now 11, he has carried a backpack on several trips. My daughter is nine and yet to carry more than a daypack, though I think she’s close to making the decision on her own.) The second question I answered by measuring his torso properly and trying packs on him. Many kids are not big enough to fit in a children’s backpack until age nine or 10—and carrying a poorly fitting pack might be the best way to turn a kid off to backpacking. My son has used and likes both the Fox 40 (skiing to a backcountry yurt in Idaho’s Boise Mountains) and the Jib 35 (backpacking in Utah’s Capitol Reef National Park), carrying 18 pounds in each pack. The 11-year-old daughter of friends also carried the Jib on our yurt trip. I think both are excellent kid backpacks, though they have different strengths.
The Fox 40 fits the smallest kids best, and has a little more padding in its hipbelt, shoulder straps, and back than the Jib 35, as well as having a nice vertical channel through the back padding for air circulation on hot days. I think it’s made to handle at least 20 pounds. But the Jib delivers a bit more support and rigidity, with its frame of aluminum rods and flexible tensioners in the hipbelt, giving it a slight advantage when your kid starts carrying upwards of 25 pounds. The Jib’s hipbelt is also adjustable for a wider range of waist and hip sizes—it can grow with your child. As for organization and features: Both are top-loaders with roomy lid pockets, deep, stretchy side pockets, and a safety whistle on the sternum strap; but the similarities end there. The Fox 40’s large, zippered, bellows side pockets (above the stretch pockets) have a functionality edge over the Jib’s front stuff-it pocket. But the Jib’s two zippered hipbelt pockets—big enough for a few snack bars each—are more useful for backpacking than the Fox’s hipbelt gear loops. Lastly, both are well-constructed packs built to last, with high-quality stitching and tough, 420-denier nylon, though the Jib’s mesh side and front pockets are more susceptible to tearing than any fabric on the Fox’s exterior.