Internal frame at a glance
- Common form
- Aluminum stays
- Alternative
- Perimeter hoop or composite
- What it does
- Moves load to the hipbelt
Internal against external frames
External frame packs put the structure outside the bag, and they've been niche since the eighties. Everything else hides it: flat aluminum stays running vertically up the backpanel, a bent tubular hoop around the perimeter, or a moulded plastic frame. Whichever form it takes, its job is to be the rigid path down which weight travels from your shoulders to your pelvis.
What happens without one
Without one, weight has nowhere to go but your shoulder straps. That's why frameless packs are so specific: they work beautifully under about 20 lb and become miserable above it, and the entire ultralight approach to gear is built around staying under that line rather than around the packs themselves.
Why the stays can be bent
Aluminum stays are the common answer because they can be bent. Most makers will tell you to remove them and reshape them to the curve of your own back, which takes ten minutes and is the single most under-used adjustment on a backpacking pack.
What this means when you're choosing
- Removable, bendable stays you can shape to your back
- How the frame ties into the hipbelt, since that junction is where load transfer happens or doesn't
- The pack's stated load rating, which is really a statement about the frame
The common mistake
Removing the stays to save weight
It saves a few ounces and removes the only thing moving load off your shoulders. If you want a frameless pack, buy one designed as frameless with a base weight to match, rather than gutting a framed pack and carrying the same load.
Common questions
How much weight can a frameless pack carry?
Comfortably, about 20 lb, and some people stretch that a little with careful packing. Past that the shoulder straps take everything and the pack collapses into a shapeless bag, which no amount of adjustment improves.
Should I bend my pack's stays?
If the maker says they're removable, yes. Take them out, hold them against your back, and match the curve of your lumbar spine. A pack that gaps at the lower back is usually a pack with factory-straight stays.