Aug 8, 2020 at 1:28 am #3669842
if you hold a rule onscreen from your wife’s ankle to her hip (in your photo)you can clearly see that her torso is flexed forward from the hip and a noticeable amount of cervical flexion.. I don’t have a goniometer handy but it looks like her torso is around 10 degrees flexed at the hip, presumably because her COG is altered by wearing that pack.
This notwithstanding. it is probably dynamic biomechanics that would reveal the efficacy, or not, of the AARN system.
Wearing a pack that changes your COG will affect your postural muscles and the biomechanics of walking, whether it’s to the degree of AARN’s advertising is a different argument.
I don’t use an AARN pack but if it brings COG forward by an appreciable margin, at or close to that of the person’s normal COG, it is likely to lead to less strain and fatigue of postural and, perhaps, locomotor muscles. Clearly the lighter your pack is, the less advantage that a balanced pack would have.
Can’t imagine it would be fun, or particularly cool on a hot day, to have those big pockets in your way though. Looks awkward and cumbersome but you can’t confirmation bias away the biomechanics of load carrying.
Walkers might exhibit a degree of pedal dorsflexion when faced with an altered COG but they certainly also have a degree of flexion of the torso at the hip.Aug 8, 2020 at 2:03 am #3669844
you can clearly see that her torso is flexed forward from the hip and a noticeable amount of cervical flexion.. I don’t have a goniometer handy but it looks like her torso is around 10 degrees flexed at the hip,
I will respectfully disagree. My wife has carried other packs, and can tell the difference.
Actually, a static measurement is not really relevant. You need to watch a person moving over rough terrain, especially climbing on rough country. It is very common for the whole body to be moving in all sorts of ways.
In this case I think Sue is just leaning against the cliff and wondering whether she really should be crossing this avvy chute. (We did.) But the next one … we did not.
CheersAug 8, 2020 at 5:10 am #3669849
“you can’t confirmation bias away the biomechanics of load carrying”
Whenever the Aarn system comes up here, there are always people who seem to believe that they have some kind of magical backpack that alters the laws of physics so that they can hang a weight off their back with no impact on their COG. This simply isn’t possible, folks. It’s not just about weight on the shoulders – it’s about walking with a natural, undisturbed center of balance.
It’s perfectly sensible to say that you don’t mind the alteration to your gait, or that you feel the benefits of the Aarn system aren’t worth the drawbacks. But you can’t sensibly say that carrying a load on your back that isn’t counterbalanced by a load on your front doesn’t alter your COG or your gait.
THE IMPACT OF A CONVENTIONAL PACK
Regarding the impact of a conventional pack, some people seem sceptical about the force diagram that Aarn uses in his advertising. This summarises the results of research by Professor Raymond Lloyd, a distinguished sports scientist at Leeds Trinity University and an Olympic coach. He has studied load carrying for decades, so it shouldn’t be too lightly dismissed. His research on the the bodypack is summarised here:
NON-ISSUES WITH THE BODYPACK CONCEPT
As for the drawbacks of the bodypack, they shouldn’t be overstated.
Yup – it takes an extra couple of seconds (literally) to put on. Not a bad tradeoff for hours of improved comfort, in my book.
People always bring up the subject of overheating, but it’s a total non-issue. The stays keep the front pockets well away from the torso. I’ve used the Aarn for long ascents in blazing heat and not noticed any functional difference.
Another issue is that the pockets can impact the swing of your arms. But this can be eliminated once you get the setup properly dialled in, at least with the mid-sized Sport Pockets. I’ve no experience of the large Expedition Pockets, but they aren’t really relevant to lightweight backpacking – they are for load-hauling.
Another reservation is that you have to be more organised with your packing – you can’t simply bung everything in the back compartment. But in compensation you have easy access to all the kit you need during the day, which I personally find a big plus – in poor weather on exposed walks I’ve literally spent entire days on my feet without taking off the pack. Once you have your packing routine sorted it’s a virtual non-issue – maybe you lose a couple of minutes each morning, but that’s about it.
Finally, the fear that you can’t see your feet is misplaced. That’s why there are two pockets – so there is a gap between them to see through, in contrast to setups with a single pocket across the chest. With the Aarn design I’ve had absolutely no problem seeing my feet on tricky ground, and because of the better balance I’d say I experience fewer slips wearing the Aarn than I do with a conventional pack.
REAL ISSUES WITH THE BODYPACK CONCEPT
The first real issue the psychological impact of the pockets in your line of sight. Again, I’m talking about my experience with the Sport Pockets here. I won’t pretend it’s ideal, particularly as the pockets on my pack are bright orange (with my own version, they’ll be black). But in my experience the brain quickly filters this out, in the same way as it filters out background noise or smells. Once you get used to the setup you really don’t notice it much.
And the second real issue is that the pockets are inconvenient for scrambling, or when off the trail shopping and travelling. The only real solution is to have a backpack that’s large enough to stow the pockets and the items inside them. It’s not convenient and there’s a modest weight penalty, but in general I’ve found it workable. This is the main motivation for my MYOG project – I’m experimenting with a system for quickly moving the front pockets to military-style side pockets when required – not something you can do with Aarn’s designs.
DECIDING IF THE BODYPACK CONCEPT IS FOR YOU
As I’ve said above, I do have some reservations about the detailed design of the packs (though I haven’t seen the new redesigns). But the overall concept is brilliant. The ONLY way to retain a natural COG when carrying a load is to counterbalance the weight on the back with weight on the front, and this is much the best way of doing it. The combination of the dual pockets so you can see your feet and the stays to transfer the weight to your hip-belt make the Aarn system a totally different proposition to other front pocket setups on the market.
If you’re happy walking with a disturbed COG, it’s really not up to me to argue – we’re all different. All I can say is that in my experience, the difference over a long day is very significant. I experience literally zero shoulder and back discomfort, and feel much less fatigued and beaten up, even after 12 hours + on the trail.
You might be surprised at the difference. Just give it a fair trial for long enough to overcome the unfamiliarity.
The problem is that this isn’t so easy to do. If I was Aarn, I’d have my distributors hire out tester packs for people to try, but marketing has never been his strong point. You could always ask for a tester, but I’m afraid that as things stand you might just have to take a leap of faith.Aug 8, 2020 at 8:00 am #3669866StumphgesBPL Member
Sean is correct. In the first Sue photo her hips are flexed, her thoracic spine is also flexed, her shoulder girdle is protracted, her lower cervical spine is also flexed and she’s hyperextended her upper cervical to keep her gaze horizontal.Aug 8, 2020 at 11:18 am #3669900Daryl and DarylBPL Member
@lyrad1Locale: Pacific Northwest, USA, Earth
I’ve used a myog backpack with a front bag for over 20 years. I was sold as soon as I hung a front bag on the pack frame as an experiment. Try it and see what you think before you invest a lot of time, energy and money in pursuing the details.
But the devil is in the details and that is mostly what is being discussed in this thread.
Best image for a front-to back=balanced load image, in my opinion, is an overhead canoe carry with the center of balance on the shoulders.
My myog backpack achieves the canoe-carry balance in a large volume backpack weighing about 1 pound. There is no need to turn this into a heavy backpack.Aug 8, 2020 at 2:21 pm #3669926jscottBPL Member
@bookLocale: Northern California
I’m sure it would be easy enough to snap a photo of someone wearing an Aarn pack and leaning forward…or flexing…or in a lot of unbalanced postures. Not because the pack is bad: but because our bodies are constantly going through all sorts of postural changes while hiking over rough terrain carrying a pack. A single photo doesn’t prove that someone is locked into a posture 100% of the time.
Frankly, when someone tells me that what I’m experiencing when carrying a pack simply can’t be true and is due to self deception and confirmation bias; and that the Laws Of Physics show THEIR opinion is correct–I shrug and walk away. They’re saying my body is a liar and They are ‘right’; and that I should trust them rather than my own lyin’ comfort. Honestly, I think the “laws of physics” argument can serve the ends of confirmation bias as well as any.
There is no universal Law O’ Physics that will dial in the single proper pack for everyone. AArn packs have been around for years, but they’re hardly used. Most people don’t like them. If it was incontrovertible because of mathematical equations that they were the one superior design in packs, you’d see a lot of them out there. You don’t.Aug 8, 2020 at 4:12 pm #3669985
In the first Sue photo her hips are flexed, her thoracic spine is also flexed, her shoulder girdle is protracted, her lower cervical spine is also flexed and she’s hyperextended her upper cervical to keep her gaze horizontal.
Dear me, and we never knew.
Perhaps she should be in a hospital bed?
But I cannot remember Sue ever complaining of any back problems in 50 years.
We shrug and walk away.
CheersAug 8, 2020 at 4:32 pm #3669996
They are popular, just not in your neck of the woods, jscott.
They are more frequently seen in NZ and Australia, particularly for the more remote walks where more gear is carried. The advantages of the pack increase with carried weight.
They’re still a niche item IMO. But, I wouldn’t dismiss the concept even if AARN’s execution is complicated.
Hikers once dismissed shoes as unsuitable for hiking – it can a long time for a paradigm to change.Aug 8, 2020 at 4:50 pm #3670011
I did field test an Aarn pack on a trip here in Oz once, but since then I have not seen any in the field.
Can’t say I have ever seen them in the shops here either.
CheersAug 8, 2020 at 4:52 pm #3670012
Well, you did present this as your exemplar. If you are waving away your own ‘evidence’ what is the reader supposed to think about your position?
When hikers have a pack on their back they have a tendency to flex their torso at the hip to accomodate the change in COG, as your photo demonstrates.
Whether this us an issue is up to the individual but I’m not sure why one would pretend it doesn’t happen.Aug 8, 2020 at 4:55 pm #3670014
There’s plenty of people using them in Tassy, two people in my club just bought one and their are outdour stores in WA, Melbourne and Brisbane that sell them.
They are becoming increasingly popular.Aug 8, 2020 at 5:36 pm #3670021jscottBPL Member
@bookLocale: Northern California
‘they have a tendency to flex their torso at the hip to accomodate (sic) the change in COG, as your photo demonstrates.”
It demonstrates no such thing. It is a random snapshot in time–literally–of one person, Sue. Doubtless pictures exist of Sean leaning in to speak with a friend. That doesn’t prove that Sean always walks with a lean-forward gait. This point has been covered. In any case, that sort of assertion wouldn’t hold up to scientific standards in terms of establishing a universal truth a- la the Laws O’ Physics.
You need to watch someone carrying a pack over time to assess how their body is carrying the load.
I have nothing against Aarn packs and entirely believe that people who use and enjoy them have found a great system–for them. Kudos!Aug 8, 2020 at 6:52 pm #3670037Nick GatelBPL Member
@ngatelLocale: Southern California
So maybe some people here are over analyzing backpacking? Seems that is what we modern humans do with just about everything in life.
Some of us have been backpacking for over 50 years without injury from our packs and not even knowing what cervical flexion is, or what a goniometer is.
I’m not picking on you Sean!
At the end of the day, it is our legs that carry all the weight of our packs anyway.
For almost 40 years I mostly backpacked with two packs, both Kelty externals; a small one and a larger one. They worked great and occasionally I still use both. They didn’t work exceptionally well off trail, and I do most of trips off trail. Thus the change to internal frame packs 10 years ago.
Those two internal frame packs worked so much better than my externals, and I have been perfectly happy with them, so happy that I no longer read reviews of new packs and mostly ignore BPL posts on backpacks. This thread caught my eye, because I had researched Aarn packs back around 2008.
When I bought my two McHale packs, I could have probably bought four or five Aarn packs for the same amount of money, but my little bit of knowledge and experience over the years led me to Dan instead. A choice I feel fortunate to have made.
And, as I mentioned earlier, a properly designed and fitted internal pack works wonderfully for me. I certainly wouldn’t want to climb up a 20 foot granite pour-over with an Aarn and those pockets in the front, and the pack looks that it might not be as stable as a good internal when moving and leaning side-to-side going up steep rock outcroppings or large talus fields. I could be wrong, since I have never used one, in fact, I have never seen one.
Last year I was on a trip, and we had to travel along the edge of rock outcroppings just below a ridge line, requiring us to hug the rock formations and locate hand holds to keep from falling hundreds of feet below. This was at least a half mile of work that probably took us a couple of hours. I would probably have fallen and died if I had those counter weight pockets in the front to prevent me from hugging rock formations. Of course, neither of us knew ahead of time how difficult this route would be, because nobody hikes up there. The route was carefully vetted, to include looking at satellite maps. My hiking partner probably has more off-route, remote backpacking experience than just about anyone on BPL.
I certainly don’t want a pack design to dictate where I can or cannot travel.
I’ll be 70 in a few months (assuming I don’t die from COVID or some other ailment), and I am more than willing to consider anything that will make me more efficient or more comfortable. Even if an Aarn pack provides some measure of improvement to the center of gravity, I have to think it to be a small incremental amount, and at this point in time, I don’t need an incremental improvement because my packs to everything I need them to do. I never wish the were a little bit better at anything.
An improvement in center of gravity, for me, is a solution looking for a need. It also seems to be the same for Roger who has an incredible amount of knowledge and experience, especially diverse experience off trail and, trips that last months, not days.
Given all of this, I am not saying Aarn packs are a poor choice. A lot of engineering has gone into their design — perhaps they are over engineered. If someone thinks an Aarn will suit all their needs, then go ahead and get one. There are many, many popular, and at the same time, poorer choices one could make. You could certainly do a lot worse by buying something other than an Aarn backpack.Aug 9, 2020 at 8:47 am #3670081
I don’t think that anyone would argue that the Aarn is the solution for every need.
First, you already own a couple of great packs, and if you’re happy with them, what’s the problem? The Aarn is aimed at people who find conventional packs uncomfortable and tiring, as I do.
Second, they are obviously not designed for sustained steep scrambling – they work best in open country (which is what most of us are doing for most of the time).
If I have to scramble with my current Aarn, I have to put the pockets and their contents into the backpack. Not ideal, but workable for occasional use provided I leave enough space in the backpack. I aim to address this, as I’ve said, with a MYOG project that would enable me to move the front pockets to the side whenever that was more convenient.
Finally, to everyone who has said they can’t be any good because you never see them, I think that this is a field that’s slow to innovate. Another example is the PacerPole vs conventional poles – in my experience, simply a better design, but you rarely see them in the field. The case for the Aarn is more complex and nuanced – I never claimed they are for everyone. But I do think that a lot of people would benefit from the system if only they knew about them and were open-minded enough to give them a fair try.Aug 9, 2020 at 12:36 pm #3670122
Sorry Stumphges I didn’t get to see your questions until now.
I think that I carried 17 kgs in the Natural Balance with food for two plus weeks. I thought it was too much for the pack.
The Universal Balance Bag doesn’t fully put all of the weight on the hip belt so it’s not at all the same as the Balance pockets on the Natural Balance and other packs that have pockets on the hip belt in which to insert the stays from the Balance pockets. Yes, they do counterbalance the backward pull of the main packbag, if you’ve packed the right way.
The Aarn hip belt has an ingenious cord running through a tube that connects the hip belt to the shoulder straps. I’m speaking from memory here so I might have messed up the details, but it’s a pretty cool system in action. (I’ll have to dig out my Aarn pack from storage to corroborate this). It’s also something that would not be transferable directly to the SO Flight One. That tube through which a cord passes along the rear of the hip belt enables sway that is counterbalanced to the movement of your shoulders. It’s pretty neat. The whole suspension of the Aarn Natural Balance is set up in a way that leaves an amount of motion and freedom that I haven’t seen from any other pack. It would be really cool if it could be scaled down to a UL application but when I tried a lighter offering from Aarn (I think it was the Mountain Magic) I discovered that the implementation was different and the comfort was different.
Anyway, the main thing is that the Aarn Natural Balance isn’t just about center of gravity. It’s also about placing all of the weight on the hips while completely freeing up the conflicting motion of the hips and the shoulders. Personally I found this latter aspect much more compelling than the balance issue, but they obviously work together.
I’m interested in adapting the Balance pockets to a Seek Outside Revolution pack. Aarn sent me the necessary hardware, so eventually I’ll get around to the mod. I can’t do it myself but there’s an awesome and rare gear repair/mod workshop in Lyon that would be happy to do it for me.
The new versions in dyneema grid are of course more attractive if they can save half a pound. But what the packs really need to cut weight is the use of carbon in place of all the aluminum used (except for the stay).Aug 10, 2020 at 2:13 am #3670214
Here are some photos to illustrate the hip belt on Aarn’s Natural Balance.
The first photo shows an attachment point for a cord (see red arrow) that runs through a channel at the bottom of the main packbag and connects to each side of the hip belt.
Here is a photo of the channel for the cord that runs across the bottom outside of the main packbag and allows the cord to connect to both sides of the hip belt.
The hip belt is attached to the frame at two additional points.
The first is a loop at center of the bottom of the packbag that connects to a thin aluminum wire bar that circles the edge of the packbag.
The second is inside and behind the hip belt that connects to a T stay composed of a horizontal cross bar and a vertical stay that runs only 2/3 of the length of the packbag body. With the horizontal cross bar and the aluminum wire edge frame, it looks superficially similar to the SO frame design, but the wire along the edge of the packbag is nothing like the 7075-T9 aluminum used on the Flight One. I wonder if tweaks to the suspension might not improve weight bearing comfort while preserving all the other advantages of Aarn’s unique suspension?
The hip belt itself is just two wings that velcro together. In that sense it is just like the hip belt on the SO Flight One, yet constructed of a combination of materials that gives it much more structure, even while remaining thin, than the SO belt.Aug 10, 2020 at 3:39 am #3670215
Correction: the stays on the Natural Balance form an H lying on its side. I neglected to mention that there is a third thick aluminum stay at the top of the main packbag.
I think Aarn uses 6061 series aluminum for these stays. Not sure what type of aluminum is used for the thick wire used around the edge of the main packbag and on the Balance pockets.Aug 10, 2020 at 3:47 am #3670216
It’s interesting how people have different perceptions. I find the counterbalance of the front pockets the key feature. I’ve disabled the sliding shoulder strap feature as an experiment and didn’t find it made much difference, at least for relatively lightweight loads up to 30 lbs or so. For you it seems to be the opposite. Perhaps it’s to do with differences in people’s gait?
I’m intrigued that he uses the hip-belt for the slider in the Natural Balance. On my version of the Mountain Magic, the slider is in a stiffened channel round the bottom of the backpack, which adds quite a bit of weight, especially as the feature also requires an aluminium stay to stiffen the lid. I was thinking of ditching it for my MYOG version, to be honest, as I’m aiming for simplicity and lightness.
I share your scepticism about the main stay system. He’s very concerned to make packs that are flexible and mould dynamically to the body in movement. But that must surely come at the cost of transferring the load to the hip-belt. He does rate the pack to 18kg, but from what you’re saying that’s over-optimistic. You’re confirming my feeling that it’s not the pack for me.
Our own Dave Chenault argues that you can retain some flexibility in a pack rated up to 18kg simply by using a single-stay system. He’s tested this pretty extensively and says it carries the load just fine:
Why one stay? I’d always assumed two were better, until I tried a single rig. The support and weight transfer is 90% as good, and a single stay weighs less. Best of all, placing the rigid frame along the spine and allowing the shoulder straps a degree of fore-aft movement due to fabric flexibility makes the single stay system provide an ideal blend of support and freedom of movement.
Sadly, it often seems that Aarn prefers the complex to the simple. I’m not the only person who thinks he over-engineers his packs – I once had a chat with someone who knows him well who very much agreed…Aug 10, 2020 at 4:01 am #3670218
I’m surprised to hear that disabling the sliding shoulder strap (which is basically a load lifter strap that runs all the way to the base of the main packbag where the shoulder strap connects to it; the shoulder strap itself is tightened by a separate strap also connected to the base of the main packbag at the same place) didn’t make a difference. Even for lighter loads it made a difference for me.
I’d read Dave C.’s comments before. It’s one of the reasons I’m interested in modifying the hipbelt on one of Seek Outside’s big packs to accept the Aarn Balance pockets (not the Universal version but the version that is properly integrated into the hip belt). SO’s external suspension looks much more effective than Aarn’s, and users claim that it does preserve flexibility in the hips.
I’m not sure about the over-engineering claims. I think it makes more sense to think of it as Aarn himself suggests. He doesn’t make backpacks; he makes bodypacks. As bodypacks, they’re not over-engineered. But whether a bodypack is something that has a real net advantage over a backpack is a question that not everybody will agree on.Aug 10, 2020 at 5:20 am #3670219PaulWBPL Member
@peweg8Locale: Western Colorado
I’m interested in modifying a couple of my packs to accept balance pockets. What hardware did Aarn send you for your mod? Was it just what is necessary to modify the hip belt for the balance pocket stays or was there more to it? Also, somewhere above in this thread someone mentioned that the pelvic form hip belt might fit other packs. What do you think? I have two Elemental Horizons packs that have a sleeve the hip belt slides through and there is a huge velcro patch that holds things together. This might work instead of modifying my current hip belts. Thanks for any tips.Aug 10, 2020 at 5:48 am #3670221
I don’t see any advantage to using Aarn’s hip belt on packs that aren’t designed to mate with the hip belt’s numerous connections points, but there’s nothing to stop you from trying, though I suspect that special ordering a hip belt from New Zealand won’t be very economical. There must be other options for simple belts that mate with velcro in the States that will be cheaper.
Aarn sent me the heavily reinforced sleeve into which the front pocket stays are inserted as well as the female parts of the snap buttons found on the front of the sleeve. Note that I am an Aarn pack owner. Don’t know if Aarn would be so responsive to non-customers. You could probably make the sleeve yourself. Not me.
Here’s a photo of the sleeve on the hip belt of the Natural Balance. The stay of the Balance Pocket is inserted into it.Aug 10, 2020 at 6:14 am #3670222
My Mountain Magic uses velcro to attach the front pockets to the hip belt, as against the bayonet system. I have to choose between the two methods for my own design.
The velcro extends along the whole base of the pocket and keeps it nice and stable. It also means you can move the pocket left or right a bit to prevent it snagging your arm-swing and optimise your view of your feet. On the other hand the bayonet would be quicker and more convenient in use.
When the pockets are heavily loaded, do you find they are stable? Or do they pivot around the single-point bayonet attachment?
Any feedback much appreciated!Aug 10, 2020 at 6:17 am #3670223
Hi Geoff, yes, I found them very stable because they are clipped to each other in addition to the pack. Unclipped from each other, they can pivot inside the bayonet sleeve on the hipbelt. I read what you wrote above and think it would be nice to have a way to quickly and easily fasten them out of the way to the sides of the pack when desired.
I had very little obstruction of my feet when using the pockets, but did encounter scramble situations where they were cumbersome.Aug 10, 2020 at 7:33 am #3670225
I’ll probably go for the bayonet arrangement because it’s quick to deploy, though as you’ve reminded me it does involve an extra strap so it’s a bit of a toss-up when it comes to convenience. It does avoid the irritation of having a pad of female velcro exposed on the hip-belt when the pockets aren’t in use. But then again, female velcro doesn’t pick up too much crud. Or perhaps there’s a third way if I’m smart enough? Decisions, decisions…
Who’d have thought that something as apparently simple as a pack would be so challenging to design? It’s hard enough to build a conventional pack as anyone who follows Dave’s multiple iterations will appreciate – and the front pockets add an extra challenge, especially if you want the backpack to work conveniently both with and without the pockets. A fun project though.Aug 10, 2020 at 10:04 am #3670235PaulWBPL Member
@peweg8Locale: Western Colorado
Jon, thanks for posting that photo. It cleared up a couple of things for me. I’m just competent enough with a sewing machine to try making that sleeve.
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