When I'm using my backpack and NOT using my hip belt, I find that it sits comfortably around my mid back. The bottom of the pack is not low enough for the hip belt to be properly engaged - it would loop around my stomach or just above my hips.
If was hiking and said "I sure would like to use my hip belt right now", would I need to loosen the shoulder straps so the pack will sit lower on my back, allowing the hip belt to loop around the illiac crest? Is it common to raise / lower a bag depending on whether you're using the hip belt, or should it always sit low enough to allow the hip belt to be engaged?