Very interesting, and thanks for the article David.
Hum ... Clearly I must be a renegade, as my thoughts are very different. Or maybe this article merely confirms many of my thoughts.
The Jam keeps changing? Maybe it STILL hasn't found a good design? Or is it that GoLite are now chasing the fashion market?
> buckling of the backpanel (and thus torso collapse) more likely. The stiffer the
> frame the less likely this is to occur, but it is a universal phenomenon
> nonetheless, save with external-frame packs.
Yes, indeed. The Amercian preoccupation with frameless packs, with all their attendant torso-collapse problems, has not really reached either Europe of Australia. The result is that European packs are, imho, generally far more reliable on long trips. Australian packs seem to be reliable too, although they have not yet got their materials beyond steel&canvas.
My MYOG external frame pack weighs 40 oz. I can carry as little as a few lbs in it, or as much as 45 lbs, in comfort. But note that it has a real frame, and suffers ZERO torso collapse. It does not have to rely on load transfer to the hips either, which is fortunate as I don't have much in the way of hips to support it. Which is entirely consistent with David's comment that 'For example, once the back panel of the Jam was reinforced with an aluminum stay, the mode of failure quickly switched to hipbelt creep.'
OK, OK, I am a curmudgeonly old renegade. But I have to carry a pack so often, and I just don't find the fad of frameless packs to be convincing.... In fact, far too many of them are just ... wierd. I think it is time American manufacturers woke up to reality. (I see Kelty still has.)