Feb 14, 2011 at 6:52 am #1269151
Recent posts about pack frames have got me wondering: what is it that makes a pack ride comfortably? What mix of design features is necessary? Since we're all looking for maximum function at minimum weight, it seems identifying exactly what the necessary functions are is a necessary first step, and then we can go about achieving that in the lightest possible way.
Obviously this is only an issue with heavier pack loads.
It seems to me that it's something like this:
-proper distribution of load between shoulders and hips
-even distribution of contact pressure on shoulder straps
-even distribution of contact pressure on hipbelt
-good fit with the wearer's body (correct torso length and good "hug")
-appropriate contact angle between bottom of frame and lower back/upper butt (i.e. angles should match)
-isolation of pointy objects in the pack from the wearer's back
What else? How would you refine my requirements? What do you think is unnecessary? What is the right way to prioritize these? Or – if you had 200 grams to use in the harness/frame of a pack…where would you spend the weight?Feb 14, 2011 at 7:22 am #1696482
David ChenaultBPL Member
@davecLocale: Crown of the Continent
Good list, Andrew. The only thing not on it that comes to mind is some way to keep the contents of the pack stable.Feb 14, 2011 at 7:35 am #1696485
drowning in spamMember
A belt that doesn't slip is important to me. I hate it when it shifts down over my hip flexors and cut off circulation to my legs. Usually I don't notice until my legs feel like molasses.Feb 14, 2011 at 7:45 am #1696488
-option of full weight transfer to the hips with minimal weight on the shoulder straps.
-wide belt but narrow in depth. Meaning a thin foam piece but wide to distribute the weight effectively.
-stiffness between belt and shoulder harness but that also contours to ones back. This means no stiffened framesheet but does mean 'floating' stays bent to the shape of my back.
-long shoulder padding that puts the adjustment buckle for the shoulder straps under by arm pits.
-serious compression options to minimize content movement as the pack gets smaller over a long trip.Feb 14, 2011 at 7:54 am #1696490
@derekoakLocale: North of England
I am making my own pack so I have been thinking along these lines. Your list is good Andrew. I am not sure however that even pressure is quite right. I remember realizing with bike saddles that a soft saddle that put pressure evenly all over was not as comfortable as a harder one that cupped the sit bones and put most prsssure on them. Concerning a hip belt I think most pressure should go evenly on the flat area above the buttocks and relatively a lot on top of the boney hip crests. To take an example I took a golite pinnacle and overloaded it. the hip belt had to be too tight to stop it sliding down, as well as other problems. I took the hip belt wings and sewed a fold to follow my hip crests. Then I gathered the top edge of the wings and reinforced the gathering with webbing. Now the hip belt sits wrapped round and ontop of my hip crests. I changed the single strap and buckle to a double strap that pulls the top and bottom of the wings not the middle ( like ULA and Aarn packs do). Now the belt does not need to be too tight to not slide down.
I think most weight 80%? should go on the hips but that does nor seem a universal opinionFeb 14, 2011 at 8:15 am #1696493
Load distribution and customization is everything. If you cannot conform you pack to your individual back through adjustments and get the load distributed onto your hips and off your shoulders it wont be comfortable.Feb 14, 2011 at 9:47 am #1696520
Daryl and DarylBPL Member
@lyrad1Locale: Pacific Northwest, USA, Earth
I love this type of thinking. One can then build a pack to meet all the specs. If it meets the specs but isn't satisfactory then relook at the specs to see what needs to change. Too often, in my opinion, packs are built to look good.
I would add 2 things to your list:
(1) Pack should be easily adjustable in as many ways as possible. My pack, for example allows for adjusting the back and front bags in relation to the frame and adjusting the frame in relation to the hip belt. This allows for changing things depending upon weight, terrain, up hill, down hill, tiredness, etc. Changing things often allows a tired or sore area of the body to recover and/or prevents it from getting more tired or more sore.
(2) Some method of balancing the pack forward to back is essential. One shouldn't have to strain forward, particulary when going up hills. Visualize a person carrying a canoe at the mid point, over their head, with equal lengths of the canoe ahead and behind. That's the type of balance I'm talking about. I used to achieve this with a high loaded pack frame that tipped the balance forward a bit. I now use a front bag. I once hiked with a guy who addressed this by bundling his stuff into a U shape and laying it horizontally on his shoulders with the legs of the U extending forward to shift the load forward.
I'd also like to add a few things about the waist belt, already mentioned by you. I'm for having all the pack's weight transferred to the waist belt but, as you say, there isn't universal agreement on this one. But I think most would agree that a good fitting waist belt is really important. A good fitting 3 ounce waist belt will add more comfort than a poor fitting 12 ounce waist belt. Making them slightly conical seems to help a lot. Material must also hold its shape. Some stuff stretches and after a few hours of use you'll find that the effective width of the belt might be down to about an inch running down the center. Not good.
I don't think I could make a pack that everyone would find confortable but I have been able to build one that I and some others find comfortable. This comfort thing is elusive and personal. Heck, some people in the world are comfortable carrying heavy weights on their head.
Where would I add some wieght for comfort? I'm satisfied with my current pack and so tried to answer the question in relation to it. I couldn't come up with anything to add for comfort. Adding weight to my pack could increase durability….but that's another discussion.Feb 14, 2011 at 10:11 am #1696530
Jared DilgBPL Member
This is a great discussion.
Would you also consider that material texture and breathability contribute to comfort? I'm thinking both in aspects of chafing from the fabric texture, and also that a lack of moisture management could exacerbate the problem since wet skin chafes quicker.Feb 15, 2011 at 5:46 am #1696881
Thanks all for the great input!
I definitely agree that tightening down the pack body and keeping it stable is necessary.
Eugene, I'm having a hard time imagining how a hipbelt could cut off circulation to your legs, but I'll take your word for it. I think you make a good point though – the harness must ride where it was intended to ride.
I think a wide but thin hipbelt sounds good – but that got me thinking about another requirement. The hipbelt must not be too wide so that it starts to interfere with one's ability to lift the legs up high in front, like when climbing steep terrain.
Derek – I can't picture the modification you're talking about on that hipbelt. Do you have pictures?
Another question: how much of the customization should be built into the pack (and therefore not adjustable) vs. how much of the customization should be doable on the fly at any time?
Daryl, you make a good point about changing things up to give a sore spot a rest. I think that's very important. As for balance, personally I like a pack with a fairly high center of gravity, because it allows one to stand more upright while walking. I do a lot of balance training for climbing so it's never bothered me from the perspective of being harder to control. I suppose I actually find it easier to control, because my posture is more normal. Also, great point on material holding its shape – this is one of my major hangups with the last big pack I made. It does exactly as you described. Now I'm wondering if Xpac, or even two layers of Xpac, would work for a hipbelt (and shoulder straps) and might even allow you to forgo webbing since the Xpac can probably carry the weight. Thoughts?
Jared, I think that could definitely contribute. It's never been an issue for me but I can see how it might be for someone with skin that is prone to chafing.
I think comfort is going to be a rather variable and personal "requirement". So maybe we are doomed if we try to put together the definitive list of requirements, but maybe we can get a "shopping list" together and personal comfort dictates which features to include.
On the other hand, minimalism requires that we eliminate unnecessary features…so what's unnecessary?
Keep em coming! What else? Why has no one picked at my list and argued anything and said I'm full of crap?Feb 15, 2011 at 8:05 am #1696913
Daryl and DarylBPL Member
@lyrad1Locale: Pacific Northwest, USA, Earth
I have no experience with xpac so can't comment on how it might work for belts and straps.
For a waist belt I'm currently using polyvynal mesh without any padding. I have a few hundred hours of use so far and it is working well. No stretch that I can notice and it allows air to get to me skin. Here's a link:
My current favorite shoulder strap is 3/8" foam, about 2" wide, wrapped in adhesive backed insignia cloth.
I've posted both of these in this MYOG forum if you want more info.
DarylFeb 15, 2011 at 7:07 pm #1697170
don't put any weight in it!Feb 16, 2011 at 2:39 am #1697286
@footeabLocale: Pacific Northwest
Pack design is completely dependant on how much weight it will be carrying.
For instance the shoulder straps. If a light load, you can get away with shoulder straps that bend and deform easily made from nothing more than nylon webbing or fabric. With a higher load you need stiffer straps that deform less easily. Otherwise if you have a heavy load with shoulder straps that deform easily this will create "narrower" straps than what they seem creating pressure points.
Same goes for the hipbelt. Same goes for the Frame. Same goes for the top of back pressure point along with the lower back as said pack frame rests on your rump.
The pack designed for 35-55lbs of climbing and camping gear is completely different set of criteria for comfort than that made for sub 35lb packs made for long distance trecking where one doesn't have to carry 20+ lbs of climbing gear on top of their clothing, camping, food weight.
I'll note that most folks on this board are into backpacking on trails and not climbing so that will determine a huge difference in opinions between end users like myself who are more interested in off trail terrain where a packs durability is a far greater asset than lightweight. For instance silnylon used in a pack, I would scoff at, but its perfectly ok on brush free trails like the PCT/AT where the only wear will be rubbing action and setting the pack down on the dirt.
As stated above, adjustability is Prime for any long distance and the ability for said buckles to hold their position is also key. Continually having to adjust your shoulder straps is Annoying!
Yes, hipbelts can cut off circulation to your legs, not to the numb state, but to where your performance decreases. This is true for heavier weights where your shoulders are taking the vast minority of the weight. They do so all the time if you tighten them enough and if they slip down off your illiac crests.Feb 20, 2011 at 11:17 am #1699123
Break the load into volumes, e.g. 2L of water, stuff sack of clothes, food, … Design a carrying method which places all weight on the hips and does not alter the natural location of a person's center of gravity. Minimize the oscillation of the load during movement.
The rest of the design is a compromise.
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