Biomechanics – Packs

"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."

In terms of durability, I would agree. I am not sure anyone said that except that generally speaking, a more durable fabric weighs more.

"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."

Yes your legs are still carrying it but now your back (or other parts of your body) isn't. For a pregnant woman with the majority of the weight in front, the back does part of the lifting. For woman who have twins (like my wife) the effect is even greater on the back not only because there is more weight in the front, but also because the weight stuck out from the body much further, adding to the effect of 'weight' on the body. I found that by strapping a 20 lb backpack on her, she felt less strain on her lower back (no, not really).

There are several reasons why a"lightweight" hiker will go over the 20lbs barrier (that is when to me the advantages of the Aarn's become obvious).
Water for a start. Not that unusual for people to have to carry a gallon or two.
Climbers with 20lbs of "Ultralight" bits (you can remove the pockets and clip them on the side, or even use them as a "summit pack")
Winter hikers. Yes I know that some say they just add a pair of VBL socks to the 3 season kit and are good for it, but that only works when we type comments on the computer…
Honestly when people describe how comfortable certain pack are reminds me of the comments I read from guys sleeping for the first time on a thick mat having spent years on a Z Lite or some suchlike. ( the best night sleep I ever had….)
But yes, when I have 10 lbs on my back then the ULA Amp (13 oz) is good enough…
Franco

Can you afford more pack weight if you are not carrying extra body weight? Just a thought.

Currently trying out an Osprey Aura. Tried Exos too. Not sized small enough. Aura similar construction. Any thoughts about metal on bone? Can you bend the bloody thing? Airspace just moves the weight away from the COM. Won't go there again.

Yes, where you place the weight is critical! The mechanical advantage of levers! I was not a physics ace. I have played on a seesaw though.

Energy usage has other factors besides the location of the load centre of mass. Allowing for normal arm, shoulder and hip swing is a factory too. Packs with stiff backs resist normal walking movement and thus require the body to compensate in other ways. New technology from Black Diamond called Active Frame (http://broadbandsports.com/node/28424 ) and (the same) systems from Aarn called U-Flow allows for freedom of movement. An advantage of the Aarn system is you get lumbar support.

So you users pick a pack and a load and I will (try) to get a budget to have walkers tested for VO2 consumption at a university. University to publish results.

I haven't looked at these particular packs very closely, but I like the idea of a front pack. When I carried my DSLR on my chest I found it very comfortable.

On top of shifting weight forward, a front pack adds capacity, if needed. I haven't been able find anything I like commercially, so I think I'll try to make one.

As far as commercial posters, what better way to learn about new products and what better way to reach a target market. Within reason of course!

David,
When you make your front pocket or camera pocket try to make it so the pocket is supported by the belt and the shoulder straps are just a guide. This is interesting http://www.cottoncarrier.com/video.html but it would be better with belt support. Cheers

"So you users pick a pack and a load and I will (try) to get a budget to have walkers tested for VO2 consumption at a university. University to publish results."

The Ohm with 25# vs the Gorilla with 25#.

Congratulations Mark on finding a USA distributor for Aarn packs- good luck and welcome to the forums. I don't mind manufacturers/ vendors posting as they can provide useful first hand information about their products, and you followed the forum rules and declared yourself.

I'm in the market for an Aarn pack, as I think the concept works. I don't have one, but have rigged up my own front packs which I use to carry extra water on drier hikes.

I really notice the difference between a 8kg load on my back, and 6kg in the front with 2kg on the back, and my system isn't as sophisticated as Aarn's. I basically just adapted some stuff sacks with straps for the waist belt, but it works for me.

Aarn also make lighter packs for trail runners, the Mountain Magic range, which will be coming out next march in 44 and 55 litre size for less weight than the traditional packs- I'm waiting for one of those.

The purpose of the front pack is to allow one to walk more upright, in a natural position, and coupled with my Pacerpoles, I've never felt so comfortable with a pack on as when I'm using my own home made design. My pack isn't SUL (tried that, didn't work for me), I use a Grivel 35+5, which weighs too much for some around here- but of course, we all hike our own hike.

cheers,
fred

Don't much care about lumbar support per se with a relatively light load. However, accomodating/approximating the S shape of the spine would seem desirable. Spine is not straight. Significant kyphosis and lordosis in the healthy back. Straight spine in some disease states — leads to real problems. Packs with rigid flat design don't make sense to me. Neither does Osprey Airspace design. I can't seem to pull the load lifters taught enough. Want to make it work for next 3-4 weeks of walking. Of course, I was forced to ditch a couple kilos. Finally being forced lighter.

BTW, in response to a previous post, woman are well designed to carry the weight of pregnancy. Some runners train up to delivery. Pregnancy + obesity + deconditioning can be a different story.

I've got one of the new MM44 sand I love it. OK it is heavy, and I could add bragging rights to my weight list by going lighter, BUT the comfort and the ability to walk further, with more comfort is worth it. Dri Bags included front and rear, mould to your body and the load lift system means the pack moves as you move

Hartley, Please have a look at the link below and let me know if a system like this would work for you?

http://www.aarnpacks.com/use/index.html
Go to CHOOSING & USING
Go down to – USING
Click on: Featherlite Freedom, and then: Custom Fitting Frame Stays

Cheers