Apr 20, 2009 at 1:35 am #1235724
I have been reading about these three subjects and it seems to me that there is a relation between them.
During my research what caught my attention was Roger Caffin's posts. He use a external frame pack, uses light flexible shoes, and doesnt need/use trekking poles. That is different from majority.
Centre of Gravity and Pack Shape
Most backpacker use packs with low CoG (center of gravity) and then they need poles for balancing and walking erect. My hypothesis is that with a pack having high CoG you dont need trekking poles for balance. This is ofcourse confirmed by Roger's view on trekking poles.
I also found another report:
Went on an overnighter this weekend using my new Peak Aspirations pack. It was my first hike using an Aarn pack
The hike was 6 miles each way…not too much elevation change…3-4 straight up 100' hills (good cardio!). Pace was between 4-5 mph
Temps down to 30*F and pack weight was 25 lbs total with 10 lb in front pockets.
3 words…WOW, WOW, WOW!
I expected a difference…I never expected how much better my hike would seem. I was hiking alone and set my own pace. I really felt great at the end of the hikes, significantly less fatigue that before (I've hiked that trail a dozen times over the years).
My balance was so much better. I'm a trekking pole guy (I blew out my ACL (knee) hiking 10 yrs ago). I felt so much better using this pack, I put my trekking poles on the pack and I hiked for 5 miles without them…and felt great!
Many backpacker also use trekking poles because they have knee problems. But poles are not a solution.
Walking barefoot, most of us naturally adopt a very different step: the knees are bent, rather than locked; the outside ball of the foot touches the ground to test it first, before applying any weight; then, if it’s safe, we roll the rest of the ball in and flatten the heel; only then does the weight come down. This is what Tom Brown and his students called “fox walking.”
Also see this link which was posted in another thread:
It seem that walking barefoot or highly flexible shoes with a pack having high CoG is lighter and better way to go.
Packs w/ high CoG:
I have a golite ion which works very well.
Also look at Aarn packs.Apr 20, 2009 at 1:50 am #1495564
Roger also doesn't really use much of hipbelt if I recall correctly… doesn't mean it will suit everybody.
The physics of packs is pretty simple, And is as much to do with how you pack your gear in the pack as the actual shape. Heaviest things should ideally go near the top. But there is a tradeoff — higher up means you don't have to lean as far to move the COG of the pack over your feet, but it is also less stable. So if you're moving over very rough terrain it's not necessarily a great idea to have all your heavy stuff near the top of your pack.
Internal frame packs can also be the "correct" shape. ULA packs, for example, seem to be narrower near the bottom and get wider near the top. The fact that they have a mesh bag on the back (not ideal from the physics cog point of view) doesn't matter too much because generally only lightweight things go in there and the packs (especially the circuit) are already pretty thin (the circuit seems quite thin, narrow and tall… an ideal combo).
As for poles, well I don't use them for stability. I use them to spread the weight and stop jarring impacts, particularly coming down hill. In places like Nepal I would use them even if I wasn't carrying a pack.
Shoes? Whatever is light that feels good to you. I hate "feeling the trail" and prefer a bit of cushion. A flat insole is fine though. Whatever works for you. I never have foot problems and that is the important thing. Quite a personal thing IMO.
Good thing that Roger's system works well for him (not much of a waistbelt, external frame pack, no poles) but I don't think it suits everyone. As always, HYOH!Apr 20, 2009 at 4:41 am #1495568
I also don't think Roger has much in the way of hips, but I'll let him clarify that.Apr 20, 2009 at 4:53 am #1495569
I think it is important to understand why certain things work and do not work for someone. This topic isnt about subjective preference/style. Lets get objective.
Afaik, most backpacks like ULA have a flat back. Now compare this to aarn and Roger's pack design.
Why have a frame?
The frame holds the blueprint of your back shape. Our frames are easy to remove and custom bend to match your shape, creating the blueprint. The frame’s job is to maintain this shape when the pack is loaded and to bring the load as close to your back as possible.
Why other packs are a backache waiting to happen
Frameless packs, and the most common internal frame system, twin vertical stays, give the worst possible shape for back comfort. When these packs are stuffed tightly, the backpanel rounds out to a convex shape horizontally (A)—the opposite shape to your back. The side profile is increased so that the load is positioned further from your back, and the load is concentrated down the spine. The the pull back pressure on the shoulders is increased resulting in a greater forward lean and increased back strain! The addition of a plastic framesheet is an improvement as it keeps the backpanel flat horizontally (B), bringing the load closer to the back.
Why our packs are backsavers
We take pack design further with the concave backpanel (C)—a custom mouldable shape- that brings the load closest to your back. The vertical divider further narrows the profile (D). The result is the most upright posture and the least back strain. Even with Balance Pockets, it remains important to keep the load close to your back, because the smaller volume in the front Balance Pockets cannot fully counterbalance a pack that hangs far from your back.
Having tall, narrow bottom, wide top, high CoG is not enough. I think it is important to have a backpanel that matches your back shape.
More surface area of contact=better load transfer to the back.
>I use them to spread the weight and stop jarring impacts, particularly coming down hill. In places like Nepal I would use them even if I wasn't carrying a pack.
Have you noticed sherpas carry heavy loads WITHOUT any poles? Have you also noticed that they dont wear hi-tech shoes?
Pls read the links I posted.Apr 20, 2009 at 7:02 am #1495579
@sbhikesLocale: Santa Barbara (Name: Diane)
But most Nepalese porters also carry part of the weight on their heads with a tumpline. Many of them also carry one small walking stick which they will shove under the load to prop up it up when they rest.Apr 20, 2009 at 8:22 am #1495598
@bleanLocale: San Jose -- too far from Sierras
You say that with the correct shape backpack one does not want / need poles.
How does this account for the fact that many day hikers prefer to use poles, even when their pack is light enough that it is irrelevant?
— MVApr 20, 2009 at 10:27 am #1495614
@redmonkLocale: Greater California Ecosystem
4+ MPH with a 25lb load !, that reviewer makes me feel like a slug.Apr 20, 2009 at 4:10 pm #1495714
@rcaffinLocale: Wollemi & Kosciusko NPs, Europe
> I also don't think Roger has much in the way of hips, but I'll let him clarify that.
Well, I do believe I have hip bones, or my legs might not work real well … :-)
But I don't seem to get much benefit from hip belts, and my hips don't stick out very much. On the other hand, my pack design puts part of the weight on my shoulders and seems to put part of the weight onto my back. That's how I have always carried a load, for the last 50 years. Works for me, but does not work for my wife, who does use a hipbelt.
But as to Huzefa's point that getting the load very close to your back: I claim that IS always important.
As Ashley said, what works for me may not work for someone else. Bit like shoes … :-)
CheersApr 20, 2009 at 8:14 pm #1495792
"Have you also noticed that they dont wear hi-tech shoes?"
There is a very good and simple reason for that, they cannot afford them.
A porter gets $2 to $4 per day, good quality (high tech…) boots are not cheaper in Kathmandu then they are in Europe or Australia and in fact dearer than in the USA.
So try to purchase good boots from that kind of money. (keep in mind that the are not always employed, so half the amount at best)
But I agree about the Arn packs.
FrancoApr 20, 2009 at 8:33 pm #1495795
Yep the porters are carrying crazy loads (up to around 60kg/150lbs or more) and doing so with their head taking most of the load. The stick is primarily there to support the load when they stop briefly every minute or so. They also have a very particular way of walking in order to maintain balance and not put too much weight on one leg (lots of little shuffle footsteps). As for shoes Franco is right. They wear whatever they can get. Very rare to see a porter with a shoe which isn't almost completely falling apart. Quite a few wear thongs (flip-flops). Tough, tough job.Apr 20, 2009 at 11:42 pm #1495826
@jephotoLocale: New Zealand
The aarn packs look interesting. The only time, however, I have carried anything in a front pouch (camera) I found over- heating a huge problem.Apr 21, 2009 at 12:52 am #1495828
> The only time, however, I have carried anything in a front pouch (camera) I found over- heating a huge problem.
Yes, that's why I'm staying away. It's a great idea for balance and distributing weight, but having a pack on your front is uncomfortable in hot conditions (I've often carried a day pack on my front when travelling). Added to that, you have the issue of it being more difficult to see your feet so not so great on tricky terrain.
If I was carrying a mountain of gear I would definitely consider it. But with lightweight gear I don't think it's worth it.Apr 21, 2009 at 1:14 am #1495830
I dont think it is so important to have the CoG high with Aarn packs because the front pockets bring the CoG forward much more effectively without the overbalancing instability of a high CoG. I carry my heavy things in the front pockets and then in the middle of the back pack (heightwise) against my back.
Aarn front pockets are well designed to stop overheating. They should not touch the body at all except at the standard support belt and shoulder straps. Mine are shaped to be mostly an inch clear of my body.
There is some reduction of view to your feet but a lot better than a chest pouch. The 2 pockets are set wide apart and you can nearly always see your feet through the gap between them.
The Aarn backpack is well ventilated too, although it hugs the back. It has 20mm (edit maybe that 10mm) thick 3D mesh against your backApr 21, 2009 at 2:45 pm #1495951
Okay, Huzefa, let's be objective-
The diagrams from Aarn are marketing tools. They somewhat misrepresent reality. Backs are not naturally rounded like that, particularly in the narrow 12-14 inch region of pack width. For a pack to find curve in someone's back the pack would have to stretch all the way across their back and onto their sides. Furthermore, I've never packed a pack so that it's round and bulbous away from my body. I pack them relatively flat. Most packs are constructed to facilitate, though not require, this. The most important "clinging" aspect of fitting a back panel to someone's back is in the vertical plane, following the shape of the spinal column. Most modern packs do this. I'd argue that Osprey's new Atmos/Exos frames actually cling pretty closely to the back. On a historical note, Gerry made packs 30 years ago with vertical dividers… no surprise, the concepts aren't new, but always fun to investigate. Work is calling…
Edit: continuing a little, I've never actually seen a pack bow that far away from a body. Seems odd. And as far as weight placement, that's another thing Gerry looked at 30 years ago or so w/CWD–the horizontal zipper packs and contoured packbags. But bottom line, if you exercise consciousness you can pack your backpack properly–instead of needing a pack that forces you to do it one way or another.Apr 21, 2009 at 3:01 pm #1495954
@theronrLocale: Los Angeles, California
I just became a believer in front packs. To try it out I got some sort of accessory pouch from an army surplus store (they're great for that) and attached it to the front straps on my pack. I had 5 lbs in the front and 15 in the back. Went for a few miles day hike and it was great. I did get a sweat patch under the front pack as with the back. I think the weight redistribution has a greater effect than you would expect. I mostly played around with my poles rather than used them too. I do believe that one of their main effects is to encourage you to stretch out your arms, thereby improving balance, and this job became less necessary.Apr 21, 2009 at 3:09 pm #1495960
@rcaffinLocale: Wollemi & Kosciusko NPs, Europe
> It's a great idea for balance and distributing weight, but having a pack on your front is
> uncomfortable in hot conditions (I've often carried a day pack on my front when travelling).
I have an Aarn pack, and found exactly the same problem in Australian conditions. I imagine that in colder conditions it might not be so much of a problem.
> Added to that, you have the issue of it being more difficult to see your feet so
> not so great on tricky terrain.
That too was a problem for me when off-track. On a track, not so much of a worry. Scrambling country – no way.
> with lightweight gear I don't think it's worth it.
Reckon lightweight is better myself too. Less load on the spine and less on the legs.
CheersApr 22, 2009 at 7:33 am #1496131
>But most Nepalese porters also carry part of the weight on their heads with a tumpline.
Since you brought up the subject I will delve in more detail.
There are several ways of hauling heavy loads: You can balance the load on your head, suspend the load from your head using a head band and tump line, or carry the load on your back using a backpack. Most modern packs are actually hip packs. You can also suspend two loads from a spring pole on the shoulder. Each method has its own mechanical stresses and energetic costs.
My concern with tump is that they stress the head and neck in a way that we're not used to or conditioned for, which can result in soreness or injury. I believe that the best load carrier is your spine. For that you dont need to stress your head and neck. Though still in use by many cultures, this may be more due to the fact that a tump are useful for carrying huge volume loads.Apr 22, 2009 at 7:37 am #1496132
>How does this account for the fact that many day hikers prefer to use poles, even when their pack is light enough that it is irrelevant?
It is related to footwear! Read this link.Apr 22, 2009 at 7:39 am #1496133Apr 22, 2009 at 7:44 am #1496136
> instability of a high CoG
I read this often. Usually the example given is of load carried on the head. With a backpack, the main purpose of waist/hip belt is stability.Apr 22, 2009 at 7:57 am #1496140
deletedApr 22, 2009 at 8:09 am #1496144
deletedApr 22, 2009 at 8:10 am #1496145
It is true that a high centre of gravity if balanced and under control is not always a problem. I once rode a penny farthing bicycle. It was difficult to get on it and get started and you had raised the stakes for injury if you fell off, but it was not difficult to ride just because you were high, it might even have been easier.
If you imagine balancing a vertical stick with a weight on the top on your palm, I can imagine it is easier to balance a stick 2' long than a stick 3" long.
I still prefer a sack with the load centre of gravity near my own.Apr 22, 2009 at 8:15 am #1496147
Brad, I agree that diagrams misrepresent the back shape. I thought the real point was to show the shape of the pack. See how the load gets closer to the back.
>Furthermore, I've never packed a pack so that it's round and bulbous away from my body.
I have seen many pics on this site of people packing their packs like that, specially those who use CCF barrel frame.
>The most important "clinging" aspect of fitting a back panel to someone's back is in the vertical plane, following the shape of the spinal column. Most modern packs do this.
>But bottom line, if you exercise consciousness you can pack your backpack properly–instead of needing a pack that forces you to do it one way or another.
I havent seen pack having compression straps right at the bottom, mostly that place is taken by water bottle pockets. One can argue that bottom is usually occupied by sleeping bag so it doesnt matter, but I think a pack with bottom as narrow as possible would be best as you can effectively use the sleeping bag to raise the CoG.Apr 22, 2009 at 8:26 am #1496151
> with lightweight gear I don't think it's worth it.
Aarn's web site agrees.His reported research can be interpreted to show that to carry an extra pound of rucksack weight you need to be carrying a load of over I think it was 10 pounds before front packs save energy. edit it was 1 kilo extra sack weight and 7 kilo load weight See http://www.aarnpacks.com/news/index.html .Look down to May 07. He does have VO2 treadmill research showing that balanced carrying saves energy. http://www.aarnpacks.com/sports_science/index.html. Is there any science contradicting this research?
You could interpolate that a very light front and back pack system that only weighed say 8 ounces more than the equvalent backpack would save energy at anything over 3.5 pounds load.
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