I had the pleasure of actually visiting Brian @ ULA in Logan, UT last year. I thought I would for sure need the Large torso, but after trying it on it was clear that it was too long for my 19". I went with the Medium - if I had of simply ordered it over the net I would have gotten the wrong size. Now I know that you probably can't just swing by his place (I was lucky and on holidays travelling through Utah), but you may want to send him a note. The key thing about the ULA framed packs is that they do not have an overly padded hipbelt but instead a really wide one, which permits some 'leaway' over the hips. In other words, your illiac crest could be at a different position than mine on the belt but it would not necessarily affect the ride of the pack on your torso. The belt also is removable and has about an inche of adjustment up or down (it is attached by velcro), effectively increasing or decreasing the torso length a bit. Hope this helps.