Backpack articulation/freedom of movement

[Stumphges]

Hi Richard,

I just found your patent last week. It was one of the things that got me thinking in the direction of this thread. Your point about packs losing flexibility when stuffed seems an important one, and articulation (possessing one or more joints) appears to be the solution to that design problem (assuming that one allows that it is a problem:). For me, ‘ultralight’ is ultimately about feeling unencumbered while carrying a necessary load, and anything that furthers that is worth considering. Yours appears to be a very impressive design. Triplanar!

Do you ever find that your pack moves against you?

 

[James Marco]

“For me, ‘ultralight’ is ultimately about feeling unencumbered while carrying a necessary load, and anything that furthers that is worth considering.”
I agree with this. But, considering a light load (<30pounds) you really don’t need a lot of gadgetry on the pack. A simple wider shoulder harness will do more for your shoulders than fancy gadgets (load lifters, internal frames to mount against.) And, just let any fabric/belts on the pack provide the articulation. You seem pretty locked in to the idea of articulation.

My daughter insisted on getting her Gregory(with articulation) at 3#11. Ten years later, she is looking to lighten it up a bit and get a smaller lighter pack. My other daughter has a G5. She has used it for ten years or so with no problems. 3pounds+ for a pack that can carry 100pounds is actually ridiculous overkill, though. I *might* get 7-8 miles in a day if I had to carry one. (I do 15+, average.) Even lightly packed, it would account for 50% of my base weight. (I am between 5-10 pounds, mostly.) Get it if you like it that much. But be aware that you will be getting a lighter pack eventually, especially if you continue to lighten your gear.

Again, articulation does nothing to relieve stress on your shoulders and back. It actually forces you to carry more weight on your upper body, down through your spine and hips, to your knees and feet. On a flat trail, it does work fine. I loaded up my daughters pack with 30pounds and she walked around the store for a half hour. But, she would prefer a lighter, non-articulated pack, today. We went out on a SUL trip a couple years ago with 9 pounds base between the two of us. She found she was carrying about the same as if it had 20pounds in it. Light weight, but not stupid light.

[Brad Rogers]

I agree in part James, but the SO is great for pack weights of 25lbs and up.  That may be a 10 pound base weight with 15 pounds of consumables for long trips or a packrafting trip where you have a 20lb base weight (including 10 lbs of packrafting gear).

For me, my next trip with the SO, I will have 16lb baseweight including a Bearikade Expedition, Bear spray, micro spikes, and sat phone, and then 20 pounds of consumables for a two week trip.  That is where the SO shines and is more what it (and its competitors like the HMG) was designed for.

I do have a well used frameless SMD Swift at 16oz and a 17oz ULA Conduit for lighter smaller loads but by 25lbs my shoulders want something more.

The SO is a lightweight load hauler competing with the HMG Porter, Exped Lightning, Cilo Gear Worksak, and maybe a couple of others.  Not only is it useful for longer trips where consumables are heavy, or pack rafting trips where you base weight  are increased, but also trips with a bulky and heavy bear can, or trips with young kids where you become a Sherpa.

[Bob Moulder]

Yesterday while hiking with my dog I made it a point to pay attention to the relationship between the plane across my shoulder blades and the plane of my lower back. The ‘articulation’ being discussed here refers to the vertical twist (tortion) between the upper and lower parts of the pack, with this twist being imparted by movements of the wearer, with rotations on the horizontal and vertical planes relative to the spine. Vertical stays that transfer all/most weight to the hips is a given for heavy haulers.

What I observed for myself is that there is practically zero change in the plane of my shoulder blades, whether using trekking poles or not.

I was surprised at how little change there was in the plane of the hips… at the outermost point (equivalent to the iliac crest) the rotation from the horizontal plane was 1/2″ at the very most and even when high-stepping over a big rock was less than 1/2″ vertically.

Now this changes when one is scrambling and having to twist the upper body while reaching up for a handhold and/or awkward foot placement. I would guesstimate vertical/horizontal displacement of 1-2″. But for my typical backpacking this represents about 0.01% of  my trail activity.

I was carrying only a small daypack but will try it with my UL setup, although at the light loads I carry I’m fairly certain there will be no difference. Many moons ago I frequently carried a ginormous McHale with 70+ lbs of stuff in it and never noticed any problem with ‘articulation’. I’d be interested to hear about actual observations from somebody carrying these much heavier loads.

I’m inclined to see it as the classic solution in search of a problem.

I googled biomechanics of backpacks and got quite a few hits… I will sift through some of these to see if they jive with my observations.

This one is interesting… read pages 13-17… “It can be seen that the mechanical energy expenditure decreases with decreasing stiffness and increasing damping ratio, however, the differences are negligible.” But I’m not sure at all that I agree with the unsubstantiated claim at the end of the paragraph: “With larger backpack loads, the advantages of lowering suspension stiffness would be more pronounced.”  Really? I don’t think this is fair to assume.

 

[Sam C]

I was carrying only a small daypack but will try it with my UL setup, although at the light loads I carry I’m fairly certain there will be no difference. Many moons ago I frequently carried a ginormous McHale with 70+ lbs of stuff in it and never noticed any problem with ‘articulation’. I’d be interested to hear about actual observations from somebody carrying these much heavier loads.

I’m inclined to see it as the classic solution in search of a problem.

The secret sauce to McHale packs can be found in images of those wearing them.  One his website, Dan refrains from including WxLxH to instead mention only circumference and total volume.  This is because the width of a McHale pack more closely matches the width of the wearer’s back.  And of course torso lengths vary as well.  Another thing with McHale packs are that the shoulder strap positions in relation to each other is wider than on most other packs with the straps dropping near vertical and right alongside the armpits.  Essentially, his packs provide maximum coverage; the more area of the pack that is in contact with back (wider, taller back panel) the more the load will be distributed across and down the back.  His packs are also built with textured fabric inside the hip-belts, for the lumbar pad, and sometimes underneath the shoulder straps.  Textured fabric (Cordura, packcloth, etc.), unlike the smooth UL fabrics favored by the cottage industry, are grippy and help keep the pack from sliding and ultimately collapsing.

His straps are also attached to the pack in a near vertical position and he sews the angle into the strap just above the attachment points.  To add, his hip-belts in non-expedition packs are in three pieces being held together by webbing.  This allows for total articulation and eliminates the need to put curves into the hip-belt wings.

This concept is also seen in larger-capacity commercial packs with widths as wide as 16″.  In the cottage industry we this in the use of wider shoulder straps and the putting of the backpad inside the pack (opposed to placing in on the exterior such as with GG or ZPacks Nero).

This one is interesting… read pages 13-17… “It can be seen that the mechanical energy expenditure decreases with decreasing stiffness and increasing damping ratio,however, the differences are negligible.” But I’m not sure at all that I agree with the unsubstantiated claim at the end of the paragraph: “With larger backpack loads, the advantages of lowering suspension stiffness would be more pronounced.”  Really? I don’t think this is fair to assume.

I read a good amount of these research papers as well.  You need to scan Introduction to find the real question that is being asked then skip to Discussion and/or Conclusion to see it has been answered.  Then you can go back and read the rest if you are interested.  Here, the question being asked if it is possible to predict how the human nervous system would react to movements and characteristics of a backpack while wearing said backpack. The answer, a few paragraphs up from the one you quoted, is, no, not at this time.

Their assumption is just that and nothing more.

 

 

 

[Richard Sellers]

Bob Moulder,

I agree with you that scrambling with a pack is where articulation is most beneficial.  However, if you have a couple of 10 or 15 pound weights, try this experiment to see if an articulating pack is for you.  With one weight in each hand, hook you thumbs over your belt at your sides so the weights are supported by your belt.  Walk around, fast and slow, look to the sides, behind you, walk up and down some stairs.  Then do the same thing with that much weight in your pack.  That should tell you what’s right for you.

You wrote “But I’m not sure at all that I agree with the unsubstantiated claim at the end of the paragraph: <i>”</i>With larger backpack loads, the advantages of lowering suspension stiffness would be more pronounced.” Really? I don’t think this is fair to assume.”

I think the claim is from the paragraph before that one. “Therefore, a soft pack suspension could reduce the risk of tissue and nerve damage (rucksack palsy), under shoulder straps and hip belts, and also of back and lower limb injuries. <u>This could be particularly relevant when heavy backpack loads are carried,</u> <u>as it has been found that some peak joint forces increase disproportionately with increasing pack load (Goh et al., 1998).”</u>

James Marco wrote:

“Again, articulation does nothing to relieve stress on your shoulders and back. It actually forces you to carry more weight on your upper body, down through your spine and hips, to your knees and feet.”

That may be true with the “articulating” packs you’ve seen, but not with a well-designed one. In mine, with loads of 25 pounds or less, I can carry almost all the load on my hips. I use a front bag hung from the shoulder straps (attached to the top of the frame above my shoulders) to counteract the pack tipping backwards, loading it so that the pack just presses up against my back, little over 3 pounds.  I loosen the shoulder straps at the bottom until they have no load on them.  No pressure on my back and less than 3 pounds on my shoulders.  I find 25 pounds about my limit of what I can carry on my hips without noticing it and add load to the shoulder straps above that.

Stumphges,

No, I have never found the pack move against me.  I have the sway straps attached to the shoulder straps instead of the hip belt.  The upper frame and pack move with my shoulders/upper body.  Only vertical load can be transmitted to the lower frame and hip belt.

[Roger Caffin]

Bob wrote:
What I observed for myself is that there is practically zero change in the plane of my shoulder blades, whether using trekking poles or not.
Yeah, I agree.
With normal backpacking weights my shoulders don’t rotate – I would be wasting energy if they did. And my hips don’t move much either – same reason. With really big heavy weights – same comments but more so.
XC ski touring is a bit different: you have to rotate your body for turns. OK, then you want a pack which closely follows your shoulders imho.
If you have ever ridden a motorbike with a pillion passenger on behind, you will know what I mean. You do NOT want a pillion who is wobbling around independant of you! You want that extra weight stuck tightly to your back – or at least sitting dead upright on the bike.

I googled biomechanics of backpacks and got quite a few hits…
Chuckle. Been there, done that.
Two main categories: fairly inept short term papers by ‘outdoors education undergrads’ who have never been backpacking (you can tell!), and erudite papers by academics who have never been backpacking either but do have DoD grants for the ‘research’. My opinions may be obvious.

Cheers

[Curtis King]

I have used a Seek Outside Unaweep as my sole backpack since 2014 and I have found it comfortable at any weight even under 15 lbs and more comfortable than any internal frame pack I have ever used. So, yes it can be a quiver of one especially if you carry over 30 lbs on a regular basis. Since there is enough left in the gear budget I am planning on adding a frameless pack this year for those trips which involve less than 15 lbs saving 2 lbs on my base weight.

The original SO frame does have excessive crimping, it would be great to hear what SO changed to avoid the crimping in the newer frames.

cheers

[Luke F]

The original SO frame does have excessive crimping, it would be great to hear what SO changed to avoid the crimping in the newer frames.

Mostly it was just varying the fall thickness to OD ratio. We have went to a frame with a thicker wall and a smaller OD that takes the bends better, I haven’t seen a crimp on a frame in a very long time. Personally I have seen exactly one frame failure from too much crimp, I am fairly certain it was one of the very first frames.

[James holden]

luke,

thanks for the offer of the narrower harness, i sent u a PM

eric O,

i think that youre likely a bit bigger than me, a S dead bird or patagucci base layer is nice and snug on me

what i suggest is that you get yr best fitting pack and measure the gap between the shoulder straps at the APEX, if they are 4-5″ then the divide might be a tad wide …. conversely if the gap is wider then it might be perfect

folks,

when folks talk about “articulation’ and “mobility” its really weight dependant … for example a frameless pack with 10-20 lbs would have very high mobility (especially climbing packs) … however stuff 30-40 lbs and itll likely barrel and get really stiff in the wrong ways, reducing mobility greatly

an internal frame is generally more mobile than an external … until you hit the limit where the frame starts collapsing, or the hipbelt doesnt do the job of transfering the load … then its as mobile as a grizzly bear hanging of yr back

the divide is “mobile” enough with 30-40+ lbs … in fact more “mobile” than some internal frames because at those weights youre not worried about “articulation”

and ”mobility” at that weight is more properly defined as the weight being held closely to yr hips and not shifting and throwing you off balance

to put it simply at 10-20 lbs the weight shifting a bit or not being on yr hips isnt a big thing for hiking … at 30-40 lbs and above on a mistep it can mean a twisted ankle/knee or SPLAT !!!

;)

 

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