>>684659By rigid do you mean as opposed to foam, or like internal vs external?
The advantage of an external frame is airflow and depending on the design usually a more erect posture.
The advantage of an internal frame is a closer more comfortable fit and usually less weight.
A curved plastic external frame, only found on military packs, is a hybrid between the two, they offer a very good fit with airflow and weight between internal and external frame packs.
I love my 1606ac alice large, with the old strait frame it was just not comfortable, but with the curved plastic frame it's comfy as fuck and really delivers on the original ALICE promise of a pack that doesn't limit your mobility.
It still lacks lift of course, for the same reason it offers enhanced mobility, because it is short and squat, and it's still 7 pounds because the Alice large is a 3+ pound indestructable bag.
Pic related.
