There are others with Kumo specific experience, but as a longtime backpacker and REI pack fitter over the last year, I have some thoughts. There is a textbook position the pack companies teach, which is that the weight bearing belt should sit on the hip shelf. Most big (maybe all?) pack companies are designing for a stereotype, but that’s not reality for most.
Some with wider hips or a gut will want to wear it higher or lower. My experience is that for years I wore my belt lower, because it wasn’t comfortable compressing my gut. When I lost weight I needed a smaller pack so the belt rode higher. Otherwise my hips were getting numb because I had to overtighten the belt.
Also, some with a running style pack aren’t looking for as much weight transfer, but help locking it into position and stop movement.
Not everyone has access to an REI, but if you do they will measure your torso and hopefully talk to you more about hip belt positioning. Gossamer Gear has a good page for sizing. There are instructions on most cottage pack sites as well – I found you need a helper, and hopefully someone with experience. I noticed GG says the “fastpack is designed to be worn higher and tighter than our original Kumo. “
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