We tested these packs by using them — a LOT. They are designed for use on trail or ultra runs, so that's exactly what we did. Our male testers wore them daily on local trail runs in the San Juan Mountains of Colorado and the Wasatch Mountains of Utah, while our female tester was scrambling up and down the rocky peaks of California's High Sierra. We also used them on our long runs in the mountains or desert and loaded them up with everything one might need for these adventures to see how well they worked.
We gave them to other runners to test and asked for the impressions of runners we saw wearing these products. Lastly, we wore them during ultra races, one of the ideal usages of these packs. Running for 50 or more miles while wearing a pack will really tell you whether they are comfortable or cause chafing. We used these contenders at several races, including the Jemez Mountain 50 mile in New Mexico, the Bighorn 100 mile in Wyoming, pacing during the Hardrock 100 in Colorado, and during the IMTUF 100 in Idaho.