Backpack articulation/freedom of movement

[Roger Caffin]

Hi Luke

Rest assured, I am quite happy to have a technical discussion. Very happy. So, in that spirit:

There is no hard-mounted cross members
I see one cross member, at the bottom. This may be different in detail from the many externals you have used, but it is still a cross-member.

Vertical stiffness is about the most it has in common with a traditional welded/jointed external
Here I agree at least in part. To my mind, vertical stiffness is crucial to load carrying for anything over 6 – 8 kg. Without that stiffness the pack would just roll up from the bottom.

On the other hand, I have yet to see any advantage to having the top end of the frame flex around. I would worry that it might fatigue over time, but that is just theoretical. It is partly based on the amount of crimping I can see in the bends at the bottom: they tell me the aluminium has been bent maybe a little too much.

Incidentally, the Features on the ‘suspension only’ page claim ‘dual ice axe loops’: I think that may be a mistake as the loops are on the bag, not on the suspension – as far as I can see.

Cheers

[Mark Fowler]

Various manufacturers have had a go at an articulated backpack.  TNF in the late 70’s had a framed pack with the hipbelt attached by a polymer central pivot/block and a few years ago Berghaus also had an attempt.  There may be benefits when carrying heavy loads but little to none at UL weights.

[Brad Rogers]

The SO frame was originally designed for hunters to carry out 100lbs of game.  I am not sure that I could carry 100 lbs very far, but the pack carries 40lbs very well, much better for me than a HMG Porter 4400, Exped Lightning 60, Osprey Aether 60, or even my McHale LBP36 (albeit with the “simple” suspention option).  I have used it from 25lbs to 40lbs and it carries like a dream.

[Nick Gatel]

I have been backpacking for over 50 years and never had a need for articulation, whatever that is. Maybe folks are over thinking this. If a pack fits and comfortably carries the cargo you are good to go. I still use my Kelty D4 and it works fine. My internal frame packs usually work better for off trail adventures.

[Pedestrian]

I’ve used a number of packs over the years: frame less, internal frame, external frame, and over the past couple of years Seekoutside Paradox (I don’t know what it’s called now). I’ve also used an HMG Porter 4400.

Of all the packs I’ve used, the SO pack is the most comfortable for carrying heavier loads. When I need to carry anything over 30 lbs the SO pack is my go to pack.

For loads up to around 25 lbs, I just use a beat up old North Face frame less pack. I’ve carried a bear canister and done some week long cross country trips in the Sierra with the old NF pack.

I just don’t understand the fuss about the Zpacks and all the other fancy packs for carrying lighter loads (for me < 25 lbs).

One can debate the theoretical reasons why the SO frame should not work. For me it just works.

[Emmanuel Romo]

I don’t have as much experience hiking, trekking, backpacking or making my own gear. I can say that as a younger adult interested in the biomechanics of the human body, I know what comfort feels like- to me. I’ve gone through many different types of packs since I began backpacking  7 years ago. I’ve tried Frameless rucks, Internal frames, external, ultralight frameless and lightly framed packs. I am 5’10’, 150 lbs with a 18.5″ Torso. I run hot.

The Seek Outside Divide has been the most comfortable pack I have tried. It strikes all the same points  everyone mentions. The tapered design makes it versatile for all kinds of trips. I chose the Seek Outside because I wanted consistent carry comfort regardless of weight and pack volume. The frame is solid, the fabric is durable and waterproof. It has all the practical features you would want for all 4 seasons. The water bottle pockets and front mesh pockets are well designed. I feel that I am more nimble on the trail with this pack, my previous pack was an MLD Prophet with lightweight suspension. The Prophet is an amazing backpack for loads under 30 pounds but I felt spinal compression and shoulder fatigue. A full wrap belt and U-frame keep my lumbar cooler than a frameless pack rubbing against my back.

 

I chose the Seek Outside Divide because I want to live simply. Do i really want to keep multiple bags just for backpacking? What about every day carry, work, school, computer bags, etc. All that excess takes up space.

The divide is not an inexpensive bag but it’s a one and done deal for at least another few years for my backpacking pursuits. Nothing will change that unless it’s it radically innovative and I just don’t see that being the case. The only new bag I would purchase would be a bag just like the Divide but smaller, 30L and capable of airline travel. This would replace my EDC bag in a heartbeat.

[James Marco]

Movement of the shoulders is only inhibited by rigidly framed packs, usually external frames or strong internal framed packs. Here is the result:

I was not happy. This was caused by slippage of the shoulder harness around my shoulder as I used a hiking staff.

With more weight, it would not have happened. 50# or so would have put enough pressure to prevent the slippage. But at 25#, this was bad. This was caused by an adjustable belt that didn’t hold very well, mostly.

Like I say, you will need two packs. A light, 1pound pack for 10-15 pound baseweights and a heavier duty pack for 25-30 pound base weights. You cannot use an UL pack for heavy weights very successfully. Nor, can you use a heavy duty pack for light weights very successfully. Neither was designed for the purpose.

 

[Bob Moulder]

If it works for you and you need the load carrying capacity and volume, that’s great. I very rarely carry more than 25 lbs, even in winter, and simply don’t need a heavier pack for it. I know it would be a different story if I were packrafting or carrying a big bear can and heavy water loads.

Personally, I derive a lot of pleasure from skipping down the trail with an 8 oz pack for 1- or 2-night trips in benign weather. Using a 44 oz pack for a 6.5 lb base does not make sense in this situation.

It’s not as if these packs take up a lot of storage space… every pack I own is stored in a single plastic tub, with room left over.

[Bob Moulder]

Ouch.

[bradmacmt]

Movement of the shoulders is only inhibited by rigidly framed packs, usually external frames or strong internal framed packs.

If your pack has load lifters, that’s operator error if you’ve got that sort of wear on the top of your shoulders… you’re not using load lifters correctly. Or the pack doesn’t fit you correctly to be able to use the load lifters properly.

[bradmacmt]

TNF in the late 70’s had a framed pack with the hipbelt attached by a polymer central pivot/block

It was called “Back Magic.” Pretty much sucked, it was too flexible.

[Kevin @ Seek Outside]

Hi Roger

Early UL frames had some crimping on the U part of the frame, and there have been some minor issues with those over time. A couple years ago we change those, and there is no more crimping plus I think the newer frame is a little more comfortable overall. Thanks for pointing out the inconsistency on Ice Axe Loops, we will clear up some older content artifacts in the next few days.

Like many have said, the primary design purpose was heavy weight usage in a lightweight suspension. If you look at one of our instagram posts from a few days ago you can see 190 lbs loaded on the suspension and the belt / suspension are solid (warning, the photo isn’t our best photo by any means).

That being said, I find the articulation and movement work well for off trail, steep terrain and moderate scrambling. I’ve used them on class 4 terrain, but on class 4 there are better, lower profile options. However, on that sort of 3/4 terrain, I doubt there are many, if any packs that can perform better and still provide anywhere near the load carriage above 60 lbs.

[Stumphges]

Luke, thanks for your comparative thoughts. Very useful info.

[Stumphges]

Emmanuel,

Thanks. You are not the only poster here who prefers the Divide even for lighter load trips. It’s opinions like yours that got me thinking the Divide could be the 1.

Pedestrian,

Thanks. I get where you’re coming from for sub-25 pound loads. I’ve used an old climbing pack with a webbing hipbelt for years as my backpacking bag. A recent disc herniation, though, compels me to get the entire load on my hips. So even small loads need something with structure. The Divide just seems to offer a hell of a lot more than a 1.5-2 pound internal frame pack, enough more to consider it for the one-pack role. If there were a 1.5 pound pack made of waterproof and very durable fabric that also transferred 25 pound loads to the hips I would be interested. If that pack also offered ventilation in the back while being more mobile than the Divide, I would be very interested. If it were cheap and I could later buy a Divide for big trips, I would be all over it:) I don’t know of any such packs, though.

Regarding designs meant to promote freedom of movement/normal biomechanics, I recently tried a Black Diamond Element 45 and immediately noticed its “ErgoActive” hipbelt and “SwingArm” suspension. I had read about this pack before trying it, so my perception may have been distorted by expectation; nonetheless, the feeling I had was that the pack was closer to not being there – my movement with it one felt closer to my movement without it – than conventional designs I’d tried around that same time.

Clearly, the lighter one’s pack the less pack there is to feel, which is the whole point of ultralight. Design features that can make a given load feel lighter or less encumbering also seem to have a place, if they work and don’t come at too big a weight penalty. (The Element 45, unfortunately, fails in this – the fancy suspension and gratuitous pocketry push it over 3#)

For me, this brings it ’round again to the Divide: If it carries so well as users say, and it weighs several ounces less than this Element 45, yet can carry four times more weight…

 

 

[Stumphges]

Brad,

Thanks for your detailed comments about the Divide and the other packs you mention, Most helpful. I’ve got 17″ torso, so the Divide should be fine. Leaning that way harder now:)

One thing I forgot to mention before is that this old climbing pack I’ve been using, the lightest I could find at the local outfitter in the late 90s, is really not that light by frameless UL standards at 2 pounds 7 ounces with framesheet and one internal stay. So, psychologically, adding 8-9 ounces to go from a piece of webbing for hipbelt to a super-adequate one seems like a very easy move, even without the waterproof, ventilated, etc. co-benefits.

However, looking in the other direction – at something like KS custom packs and the possibility of an XPac bag at little over a pound – does tempt toward irresponsible credit card use and a perfect two bag solution.

[bradmacmt]

nm

[Luke F]

I see one cross member, at the bottom. This may be different in detail from the many externals you have used, but it is still a cross-member.

Yes, but as I keep trying to say, it is not a hard connection but a joint, hence the “hard mounted” modifier to my statement. In all other rigid externals I have seen the cross members are either welded, riveted, or otherwise attached in such a way that the two halves can not move in relation to each other beyond the flex allowed in the materials.

Even if the SO frame had 3 or 4 welded cross members, the frame shape itself would be enough to separate it from most externals, I have only seen the tapered, narrower top on a very few internals.

[James Marco]

“A recent disc herniation, though, compels me to get the entire load on my hips. So even small loads need something with structure.”
Boy, I know that feeling. I had surgery in October to remove part of one. As far as my shoulders, I cracked a vertebra at C7. I cannot use load lifters except to minor effect or my arm tingles and goes numb with loss of mobility. For the past 40 years, EVERYTHING, except for 3-7 pounds goes on my hips. I can slip one arm out to strip off my sweater as I hike, for example.

I never carry more than 27#. And that only a couple times in the past 20 or so years. I have trouble accepting any pack that weighs more than 5% of my total pack weight. 3-4% is my usual with a 23pound pack in a GG Murmur (with pad support, bumps to my body, and hip-belt) for two weeks. With my wife or daughters, I use a larger, 15oz pack and carry 25 pounds for a week out…even with fishing gear, saw and camera gear. I never look to haul 100 pounds.

But, for training hikes, I haul around ~50# every day for 6-7 miles. This is an OLD pack with a U shaped internal frame(magnesium) that the hip belt mounts to, and, an adjustable strut that slides behind it to adjust torso height for a shoulder harness/pad mount. This was purchased in 73,74? Made in Schenectady, NY. Still going strong after several thousand miles.

[James holden]

stump …

last year i was looking for a pack that would solve anything above 40L or so for scrambling, hiking, etc ..,

eventually i settled on the SO or the HMG …  most folks on BPL seemed to be singing the praises of SO and how it basically fit anyone so i went with the divide …

when i got the pack i immediately notices 2 issues

• the apex of the shoulder strap gap is around 6-7″ … most commercial packs are around 4-5″ … so the shoulder harness is fairly wide …
• the divide is not a “mobile” and “streamline” pack despite how some BPLers say it handles like an internal frame … you definitely notice this pack compared to climbing/mountaineering packs (even internal framed ones)

i managed to find a bit of a fix for the shoulder harness issue, but its not ideal … the pack fit now works but is not ideal for me

the mobility issue is a non issue with hiking … but with more vertical endeavors, well i dont use this pack

what the divide does VERY well is carry loads … it carries 30+ lb loads better than any pack ive tried

if yr always 20 lb+ and above then the divide is for you IF it fits you … especially if you want to feel almost no weight on yr shoulders … with good weight the divide might be one of the “best handling” packs due to the load transfer

however if yr looking for something to perform like a frameless or internal framed pack at < 20 lbs loads … IMO the divide isnt the one

just as a reference i have ~18″ forso, wear S to M in dead bird and pataguicci … and i feel im probably just barely on the lower end of the divide fit (even with the shoulder strap mods) …

;)

 

[Eric Osburn]

Eric, do you have small/narrow shoulders? At 18″ you’re within 1/2″ of my torso length but I have above average shoulders for my height. I’ve been interested in the SO packs but have seen your posts and it’s of some concern for me. For reference, most medium pataguicci is very snug on my through the chest and shoulders.

[Luke F]

To eric chan; we are currently working on a narrower harness (whether it will replace the current one or be offered in addition to the current one is still being decided). I should have some samples ready early next week and you are on my short list for testers, if you shoot me a PM I can probably get one in the mail mid next week.

Our traditional customer base has been pretty big guys, since we released the divide the demographics have shifted to more normal sized folks, and we are still adapting.

[Brad Rogers]

Eric Osburn – Not that I am doubting Eric Chan’s issue at all, in fact I have no doubt it is valid, but as another data point, I am 6′  163lbs and wear a 40 sport coat and I have noticed no issues with the harness.  I may not be normal though as I have a long torso and short legs.

Pack fit can vary greatly from one person to another.  To me other than shoes, it is the most personal piece of backpacking gear.

I agree with Eric Chan that  loads under 20lbs are not the type of load where the SO shines.  I have carried loads from 25lbs to 40lbs in it very comfortably.  Below 20lbs I use a smaller, lighter pack.

 

[Eric Osburn]

Brad, thanks for your reply. I’m 5′ 5″ and 163lbs with fairly short legs. For my height I have large shoulders, between a 40 short and 42 short for suits and most medium tops are tight through the lats, chest and shoulders.

I’m very interested to see how the narrower harness works out for Eric since it’s been one of my only reservations on pulling the trigger on a Divide.

[Richard Sellers]

To the question of can a light weight articulating pack be built and if it can, is it worth it I’d say yes to both questions.

As far as being possible, I designed and built an external frame pack a couple years ago that allows complete freedom of motion, not just flexibility when not stuffed full like an internal frame pack.  It has a full frame, holds 49 liters and weighs 1.9 pounds, 62 liters and 2.4 pounds if the removable top and front pockets are included. It was designed to carry 50 pounds with a safety factor of 3 so it’s not just for light loads.  It’s made with graphite composite and full dyneema fabric (from McHale packs), but a prototype out of aluminum and normal pack material didn’t weigh that much more (just harder to build).

As far as being worth it, I typically carry 25 to 30 pounds, and with it adjusted to put most of the weight on my hips, I barely notice that I’m caring a pack.  It’s to the point that I rarely take my pack off until I’m done for the day.  I’ve worn it on the ridge bolder scramble on Granite Mt (near Snoqualmie pass), up to Tuck and Robins lakes and beyond to the top of Granite Mt,  and to the top of Mt Sahale in the WA cascades. No restriction to any movement.

 

 

 

[Roger Caffin]

But do you need the ‘articulation’ (whatever that is)? I would say no.

I build my external H-frame packs with a seriously NON-articulated frame and a light hip belt – more for anti-sway than load carrying. A sprung mesh across the frame gives me good ventilation and comfort.

I have taken these packs on extended summer walks here in Oz, winter ski-touring with large loads during the walk-in (skis and boots plus winter gear), and on numerous 2+ month long walking trips in the European Alps. I have tried other commercial packs but keep coming back to these. They work.

I am not saying my design is better than anyone else’s. I am just saying that you do NOT need fancy features, but you DO need a good frame up the torso to stop the bag from collapsing.

Cheers

[Author]

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