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Does a frame/suspension contribute to pack longevity?
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Ozzy McKinney
(PorcupinePhobia) - F

Locale: PNW
Does a frame/suspension contribute to pack longevity? on 11/06/2013 18:57:52 MST Print View

I have a ULA Circuit, and I know I'm not alone in just loving the crap out of it. I feel like it is great for almost any trip I do, from UL overnights to multi-day mountaineering. I know that many folks have had their ULA packs for thousands of miles, and I really hope I do the same.

Every now and again in the PNW, I run into tough old climbers with McHale packs that are 20-30 years old and look brand new. It is obvious that these packs (which for the sake of this discussion we will consider the Gold Standard of durability) are made with the most burly materials, meticulous craftsmanship, and probably unicorn dust or something.

What I've been wondering is whether or not a frameless ruck, made in the same manner with the same materials, could last as long as a McHale pack, which has some sort of superior alien technology incorporated into the suspension. Does the frame and suspension contribute to decreased stress on the materials in some way, or would the same pack with no frame (not literally) also provide a happy hiker with decades of use? What do you consider the Gold Standard of durability in UL or frameless packs? What "weak points" exist in UL packs in regard to longevity?

Max Dilthey
(mdilthey) - M

A Synopsis of Theory on 11/06/2013 19:18:25 MST Print View

Generally, if the frameless pack is constructed in a way that distributes weight evenly across its seams and stress points, there's no reason for material failure after X number of miles. Packs wear out from the following reasons:

1. A seam was stretched beyond it's breaking point because you carried too much. This doesn't change over time, it's a constant, except when we start talking about #2.

2. UV damage/fiber damage. Some fibers and materials like silnylon will begin to break down from exposure to sun and water. Some do this slowly, like, on the scale of decades, and others break down a bit quicker. There's also such a thing as bending strength; fibers like wool can be bent tens of thousands of times before breaking, but synthetic fibers usually only get a few thousand. On points on your pack that bend with every step you take, you might see wear after 3,000 miles or so. Maybe not even then.

3. You did it. Dropping, scraping, throwing. General abrasion from use. Rips because you pulled too hard on the shoulder strap in the wrong direction. Etc.

So, to answer your question in a roundabout way, McHale packs last a very long time because weight is well-distributed, the seams that undergo the most stress are reinforced, he chooses fabrics that have low decomposition rates, and his packs are generally free of flaws like weak spots. An UL pack can be designed to distribute the weight of the pack evenly across an integrated foam backpanel, or across a shoulder or waist strap, and most are. Cheaper ones don't distribute weight across enough stitches to ensure that the load is underneath the breaking threshold for the stitch, and you get damage over time.

What does this mean for your ULA pack?

It's well constructed to redistribute weight, so if you're a few pounds under the max load, it'll keep performing indefinitely. You will likely drop it on rocks and sand enough times to wear it out by the time you complete several thousand miles, which I suspect is why most people replace their pack.

Hope this is helpful.

Edited by mdilthey on 11/06/2013 19:19:06 MST.

Andrew F
(andrew.f) - F - M

Locale: San Francisco Bay Area
Re: Does a frame/suspension contribute to pack longevity? on 11/06/2013 19:29:43 MST Print View

I don't think framed packs have any durability advantage. What matters is the pack material and stitching design/quality. If you want the gold standard of pack durability, well, you already mentioned the two that come to mind: ULA and McHale. My Circuit looks like the day I bought it and has well over 100 days of use.

Dave -
(FamilyGuy) - F

Locale: Up there
Re: Re: Does a frame/suspension contribute to pack longevity? on 11/06/2013 19:37:31 MST Print View

No difference. A packs durability is due to construction, hence why Mchale packs last.