Using ULA Circiit without frame/stay?

Sorry, that should be 'Circuit' – how do I edit a post once it's up?

I experimented with removing the al stay (4 oz), the hoop (2oz), backpanel foam (2oz).

Its not worth it. Not even close.

You will never feel that 8 oz, and it makes a world of diff in how easy it is to pack, and how comfortable it is. Worth every gram, seriously.

I agree with "MB", keep the hoop and stay. Comfort is NOT just about weight carried, it's also about how you carry the pack on YOUR frame.

Pack frames are (if a pack is well designed) multi functional. To wit:
1. transfer pack load mainly to your largest bones and muscles, pelvis and legs, "unweighting" your shoulders/spine.
2. give more shape to the pack easing loading and unloading
3. often promote air circulation on your back
4. allow "lift straps" to be attached to the top of the frame, permitting the pack to be steadied (tightened in to your back) on uphills and climbs and loosened to let the pack lean back on steeper downhills, balancing hyour vertical load better.

Not the ULA Circuit specifically, but there are plenty of frameless packs that carry very comfortably — if packed to no more than 23-25 lbs. total pack weight. When using a frameless pack (and I have used various different ones) — I usually slip in a piece of blue foam, cut down to match the size of the pack back — then pack up everything and cinch down tightly.

I see no obvious reason why the ULA Circuit couldn't be used as a frameless pack.

Out of curiosity, I set up my Circuit with a total weight of 10 kg (22 lbs).
No problem obviously with the frame and stay,it appeared at first to be the same without but possibly more weight (almost all?) without the frame gets shifted to the shoulders.
I will need to try again but that is a first impression comment.
My U frame and stay are a combined weight of 110g (a bit under 4 oz)