LS21 / VX07 sturdy enough for 45 lbs max load backpack?

I don’t think I’d be concerned with the ls21 pack. I do not have experience with vx07 but I do with lso7. Different materials but I would be a little bit hesitant, although depending on which manufacturer is making these packs (is it seekoutside?), the construction methods is also a very important aspect.

Some of these companies I trust have made good choices on materials and construction but others maybe not.

I am far from an expert on fabric but I have have a small frameless pack made from VX07. I would not want to rely on it for a pack carrying a load of 45# particularly if you would be doing any bushwhacking.

You might find Dave’s blogposts on fabrics useful. I believe this is the most recent and it links to his two older posts on the topic in the first paragraph.

I get my VX07 and VX25 (hot lime!) today in the mail. I don’t have experience with any of those fabrics yet, but we’ll soon find out on the X-Pac! I would think that the fabric itself wouldn’t be most of the issue. Rather, the seams/reinforcement and mainly the suspension system will determine how comfortable it’ll be.

Here’s a decent review on a 3F UL pack, assuming it’s a little smaller than the one your specifically looking at, but it’s a good review none the less: https://www.youtube.com/watch?v=FDJG6T–KOA. Some of the product details on websites like Aliexpress are a little less forthcoming.

Also… shameless plug, I have the Gregory Parragon 58 (older version) and it rides like a dream. I’ve seen it on sale now for about $175 USD (excluding any duties/import fees), since a new version is out (which might save you a few ounces). It’s a beast of a pack, and stripped down you can get it to a little over 3 lb for the M/L size? I’ve used it extensively for the last few years, and it carries heavy loads PHENOMENALLY. I carried 50+ lbs (20 lb water, 10 lb food), and while my knees didn’t love me, the pack rode great. Not quite ultralight, but I think 45 lb will be uncomfortable in any ultralight pack for too long a period, regardless of fabric.

Ah, thank you for the feedback, the blogpost was also a very interesting read. I read the two older ones, but not this one.

Overall I think, this supports what I learned from reading a lot about these fabrics:

They are great for what they weigh, but maybe not  necessarily what you are looking for, when you need to carry high loads.

To be honest I really like my old backpack (except for the weight). It carries 45 lbs very comfortably, has a front opening and I modified it a bit so that it even has a front mesh pocket. Maybe I just wait until I have some money at hand and then decide again, if I want to invest in some weight savings. (There are also very interesting, but expensive backpacks like the Granite Gear Blaze 60 or the Seek Outside range).

Until then the Gregory really sounds interesting and maybe I will also look into the Osprey Exos 58 again…will check those out.

“…I doubt that the LS21 or VX07 are sturdy enough to support loads of 20 kg in the long run.”

I think either fabric is strong enough structurally, provided the construction and sewing is on point.  Hard to evaluate that from a distance.

If you’re regularly loading the pack to 20kg I’d want something a bit burlier just to manage abrasion.  Harder in my experience to be nice to a pack with 20kg, easy to baby a bag with half that weight.

How much weight is going to be in the pack is less important, in my opinion, than where you are going to use it. My ski pack is 210d oxford, typical start of trip load is around 40 lbs – though often skis and boots are added to that for all or part of the first day before the snow is reached, making the load closer to 50. No problems at all with the strength or durability. But that is a low abrasion environment. Alpine or desert, different story. Mostly forests would be somewhere in between those extremes. Good sewing and detailing can make even a very light fabric into a pack that is strong enough for heavy loads. A heftier fabric is just for durability, so your choice; how long do you want it to last?

I think the LS07 and LS21 are quite strong enough for a pack of significant capacity. This (grey one) is mine (MYOG), using mainly LS07, with silnylon throat and LS21 base.

Hard 7 day trip in the mountains.

Cheers