I’ll call them Monday, but do you know if the frame size has anything to do with torso size? I see the sizing on the shoulder straps but no mention on frame size unless I’m missing it.
It does but it isn't exact science it's more of a suggestion, for example, I'm 6'1 180lbs but I only have a 17" torso, I'd be recommended a 24" frame or 26" if gearing for really heavy loads.
With my Seek Outside pack it comes as 24, then extensions can be used to go up to 28.
I ended up liking 28" the best and that is what I run, I trained and ran this thing with 30-83.5lbs while figuring out all the adjustments and testing what I liked. Up and down steep stairs, and ran two stairs at a time to magnify that and stress hipbelt fit.
When I found that I liked the 28, I went back and re-tested with the 26 and 24, it still came out 28...
So I would be an example of someone who really didn't fit "the rule." Which is also why the Seek packs are nice, 26 or 24" is only a minute away for me if I decide I want to switch back. And of course I can cut the extensions and get anywhere between 24-28 that I want as well.
If you are cemented into a frame height, I wouldn't go below 26" frame height if you're a male above 5'6, but that's just me, get the 26, now if they have a 28 or 27, between those and the 26... well, that will be personal and I'd try them.
The difference in carrying weight comfortably can be night and day, I also found that true with the lumbar pad, and with the specific foam in the lumbar pad even. Lumbar sucked, I took out the high-density foam and just kept the puffy soft stuff, the difference was extreme, it was way way better.
I still bounce between no lumbar pad and that soft lumbar pad though.
Anyways, long story short, this stuff can be very personal and it can make an insane difference. But for frame height, go 26+ unless you'll always be below 30lbs and you want a short frame for some reason.