Biomechanics – Packs

[Mark Keown]

Climbing out of my kiwi hole…
AarnPacks.com is the designer and manufacture located in New Zealand.
AarnUsa.com is the distributor in the States. I work for the AarnUsa but I'm located in New Zealand.
The research has been done, reviews have been made and heaps of user testimonials have been collected. Go to AarnPacks.com to see the Core Principles, Features, Sports Science, Testimonials… Please look at the News section about the 70+ trampers still enjoying the outdoors. To look at it all will take several hours and there is good technical information about backpacks that will apply to any pack that you are considering.
AarnUsa.com has stock of a few Aarn packs now and will have most of the full range in March.

[Sanad Toukhly]

Your lightest pack is over 2 pounds. This is considered extremely heavy for most people on this site, including myself.

-Sid

[Jace Mullen]

Sid, They are heavy, but the weight it also on the front, wich makes the wight negligable, as it works as a counter balance.

-Jace

[CW]

Sid, They are heavy, but the weight it also on the front, wich makes the wight negligable, as it works as a counter balance.

Weight is not negligible. Doesn't matter where it's carried, extra weight is extra weight.

[Hendrik Morkel]

>>Sid, They are heavy, but the weight it also on the front, wich makes the wight negligable, as it works as a counter balance.<<

>Weight is not negligible. Doesn't matter where it's carried, extra weight is extra weight.<

What Chris said.

Also, I'd recommend let your satisfied customers do the marketing here on BPL, and not come here yourself.

[EndoftheTrail]

Just voicing my own view… I think it's fine for gearmakers to post/announce new products, etc. here — as long as they clearly identify themselves — which OP has done.

[Dan @ Durston Gear]

"weight it also on the front, which makes the weight negligible, as it works as a counter balance."

If only it was this easy :)

[Jace Mullen]

I meant, it creats an effect that makes the weight SEEM less, not that it was negligable. Sorry!

-Jace

[Tom Caldwell]

I've already got a counterweight on my front. I need a backpack to straighten my spine.

[ben wood]

"I've already got a counterweight on my front. I need a backpack to straighten my spine."

is it due to beer, like mine?

[James Klein]

I wouldn't say the additional weight of the backpack is negligible. Your feet and shoulders will certainly feel the additional weight. Your back, though, would benefit from the "counterbalancing". The better you are able to center your carry weight around your center of gravity, the less bending stress you will feel in you core and the less awkward your posture will be. This is a very important factor in how comfortably you will be able to carry a given load.

[Mark Keown]

Chris, You are right that energy used is proportional to the load but dose the location of the load on you body make a difference? Research by the references below show that the location of the load has a affect on the energy used when walking up-hill and down-hill.

Lloyd R. and Cooke C. "The Oxygen Consumption Associated with Unloaded Walking and Load Carriage with two Different Backpack Designs" European Journal of Applied Physiology

Heglund NC, Willems P.A., Penta M.C. & Cavagna G.A. "Energy Saving Gait Mechanics with Head-Supported Loads" Nature 375: 52-55

Professor Stephen Legg. Centre for Ergonomics, Occupational Safety and Health, Massey University, New Zealand.

As the load unbalance increased so dose the energy usage. Interestingly research shows for a person walking on level ground and having a totally balanced load (of 20% of the persons weight) the energy usage is comparable to walking with no load.

A smartly packed backpack places the load closer the centre of mass of the body – reducing the energy used to carry the load.

Where should the load rest:
To keep the stress on your back and shoulders to a minimum the load should rest on the hip belt. But the force down from the pack should be balanced with a force down on the front of the hip belt. So what ever front loading system you use the majority of the front load should go to the hip belt – resulting in balance around the hips and upright posture.

[David Ure]

"Weight is not negligible. Doesn't matter where it's carried, extra weight is extra weight."

No – it doesn't work in a vacuum. 10 pounds held out from the body has a greater strain on the shoulders than if it was held against your chest. A framed back will shift the weight were it should be – to the spine and hips. For a more detailed discussion from Lightweigh Backpacking and Ryan Jordan.

If 2 lbs is heavy for a framed, durable pack, then I guess I will let my membership lapse as I am clearly not the norm, at least according to Sid. Ah, to trek on groomed trails.

Hendrick – he explained who he was in the original post. We allow other Cottage producers to post new additions to their lines. What is the difference here and when did you become the forum police?

[Tom Caldwell]

""I've already got a counterweight on my front. I need a backpack to straighten my spine.""

"is it due to beer, like mine?"

Maybe a little, but mostly genes and the fact that I like to eat real food and don't exercise 5 hours everyday.

[BlackHatGuy]

"Just voicing my own view… I think it's fine for gearmakers to post/announce new products, etc. here — as long as they clearly identify themselves — which OP has done."

+1

[BlackHatGuy]

"Your lightest pack is over 2 pounds. This is considered extremely heavy for most people on this site, including myself."

ULA Circuit gets lots of pretty good reviews on this site. 39 oz. (medium torso) with no add ons. Six Moons Starlite, also well reviewed. 30 oz. with stays. I've even read some posts on this site of folks using (and liking) the Gregory Z55, and that's around 3 lbs, if memory serves me correctly.

I like my Ohm quite a bit. That's around 28 oz. as I have it configured. So I wouldn't say most people on this site would consider a bit over 2 pounds as "extremely heavy." I might, instead, say that it's reaching the upper limits of what people on this site might consider, depending on load. FWIW.

[Diplomatic Mike]

I too have had a visit from the forum police when i was selling something on here. :)

Maybe folk should give Hendrik a bit of leeway though, as English isn't his first language. The nuances of a missing letter here or there can give a different tone to what was intended. ;)

[CW]

My point was your feet will feel the 10 lbs whether you carry it on your back or your chest. I don't see what holding 10 lbs out in front of you in an effort to affect your shoulders has to do with a conversation about packs.

[David Ure]

@ Chris – the point I was trying to make was that if you had a weight that was counterbalanced in front to offset the weight in the back that will always pull you back a bit (even if you don't necessarily feel it), the combined effect will ensure that any weight is as close to one's center of gravity. This is how I understand it.

[CW]

A lot of us do this already with A/R style water bottle holders on our shoulder straps. I'm not saying the AARN design isn't somewhat unique but you can accomplish the same effect without the added pack weight.

[Diplomatic Mike]

How you carry that 10 pounds is relevant. If you carry it on your back for 15 miles you probably wouldn't notice it.
Try carrying a 10 pound bag in your hands for 15 miles and you will.
No matter the weight we carry, how we carry it must make a difference to how tired we are at the end of the day.

[CW]

The weight distribution concept isn't without merit where certain parts of the body are concerned. Take a pregnant woman for example, they carry all of the weight on their front and as a result generally experience lower back pain. But, as far as the legs are concerned they're carrying more weight than their skeletal structure is designed to handle. Even if you redistribute the weight so it's balanced front and back, your legs are still carrying more weight than they're built to handle and you'll feel it.

[Diplomatic Mike]

Your body will feel the weight no matter how you carry it. In a perfectly balanced pack, your legs and feet will take most of the strain. In a pack that isn't balanced, then other muscle groups will also be suffering fatigue as they work to bring you back into balance.
Most of us on here carry weights that are pretty low, so the effects are minor. But it does have an effect.

Probably the most efficient way to carry weight isn't a pack, but some kind of multi-pocketed jacket.

[Franco Darioli]

OK. First I would like to state that as long as people make their association with a product known (or are obviously already known to us) they should be ENCOURAGED to comment here…

Now, I happen to have a couple of them Aarns as well as some other packs.
Weight is weight however as pointed out by others HOW you carry the weight makes an enormous difference.
For example I carry 15kg or so in my Aarn Featherlite Freedom as comfortably as I when I have about 11-12kg in my Circuit.
As an experiment I loaded 25kg on a bigger Aarn (2.1kg) , I could move easier and faster with that than 18kg inside my Aether 60 (1.5kg).
If this does not make sense, try walking holding on one hand a 15lbs bag of groceries , then have 10lbs on each hand, tell me which one feel "lighter" …

Chris Wallace
"A lot of us do this already with A/R style water bottle holders on our shoulder straps. I'm not saying the AARN design isn't somewhat unique but you can accomplish the same effect without the added pack weight."

Similar not the same. When you attach weight on your shoulder straps the weight is on your shoulders. With the Aarn's the weight is transferred to the hips. Then it depends where you want the weight to be. (but if you prefer it on your shoulders, you can do that as well with the Aarn's)
Franco
BTW , I get paid 1 c for every comment I make about my favourite gear. That gets rounded off to 0 at the checkout counter….

[Sanad Toukhly]

"If 2 lbs is heavy for a framed, durable pack, then I guess I will let my membership lapse as I am clearly not the norm, at least according to Sid. Ah, to trek on groomed trails." -David Ure

Well, I probably should not have spoken for everybody. I suppose too often I forget that this website is called Backpacking Light, not Backpacking Ultralight.

For me, carrying a lighter pack that allows me to have a 4 pound base weight is much more comfortable than getting a heavier pack that distributed the weight more efficiently.

By the way, I do my fair share of bush whacking. I disagree with the implication that a 2+ pound pack can handle off trail trekking any better than my pack at less than half the weight.

Again, I should not have assumed others had the same view as me with regards to what is considered heavy.

-Sid

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