Example of a SUL internal frame backpack?

But, Tadpole, why would a SUL hiker want such a large pack?

Assuming that extra space is for food/bear can and a long distance hike, and the weight is not SUL anymore, how about a Gossamer Gear Mariposa?

A few points of consideration:

With a < 5lb base (or even < 10lb base), a well packed backpack will not collapse, therefore making a stay or frame unnecessary weight.

Also many SUL hikers don't use a pack with a belt (or a simple webbing strap for stability) and with all the weight on your shoulders a stay or frame performs no function at all.

That said, one pack does come to mind that meets your requirements; 45 liters and has actual stays; the Zpacks Arc Blast, at 17 oz.
However even at a mere 17 ounces, that still would consume at least 21% of your total base weight if you were looking to go SUL.

If you're carrying 8lbs of water and 4lbs of food, is it still SUL? ;^)

Maybe Joe at Zpacks would put an Arc Blast-type CF frame on a Zero for ya, and a itty-bitty hip belt!

But even the Arc Blast 45l doesn't have a 45l main bag… that's the total volume including front mesh and water bottle pockets.

OK, guess I've asked this question in the wrong forum.

I perhaps wrongly assumed that SOME SUL backpackers used framed packs.

Or at least my question been answered by non-frame users.

> Bob, thanks for the info. Looks interesting.

BTW, sorry for posting my previous answer here on this thread. It was meant for another thread. (Senior Moment strikes yet again.)