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The Effectiveness of Stays


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  • #1490053
    Jim MacDiarmid
    BPL Member

    @jrmacd

    Angela,

    I have a GG Gorilla right now. I've been testing it for about a week at home. I'll look at it and see if the shoulder straps are attached to the top of the stay frame. Sewing in some load lifters might appeal to me as well if it is possible.

    #1490085
    Lynn Tramper
    Member

    @retropump

    Locale: The Antipodes of La Coruna

    "I'm wondering now if stays are more important in helping to keep a pack shaped to the curved human back than in transferring the load to the hips,"

    No science here, but the rigid LuxuryLite frame is not shaped to the back, yet many people such as myself find it a much more comfortable way to carry a load. the combo of instantly adjustable back length and super-wide hipbelt linked to a rigid frame allows all of the weight to ride on hips, with no strain on shoulders (an no need for load lifters). maybe not a custom back fit, but the gap between your back and the pack alows superior ventilation that would be lost with curved stays.

    #1490103
    EndoftheTrail
    BPL Member

    @ben2world-2

    Transferring weight from shoulders to hip is the primary and thus most important function of your pack frame — including the stays. As for bending the stays to conform better to your back — that's more icing on the cake.

    #1490105
    Lynn Tramper
    Member

    @retropump

    Locale: The Antipodes of La Coruna

    "Transferring weight from shoulders to hip is the primary and thus most important function of your pack frame "

    How about those hard-core old-timers who had rigid framed packs but no hipbelt! Eeeeywww. Them was the good old days!

    #1490109
    Nick Gatel
    BPL Member

    @ngatel

    Locale: Southern California

    Lynn,

    I resemble that remark :)

    #1490112
    EndoftheTrail
    BPL Member

    @ben2world-2

    Way before my time… :)

    #1490118
    Angela Zukowski
    Member

    @angelaz

    Locale: New England

    "I have a GG Gorilla right now. I've been testing it for about a week at home. I'll look at it and see if the shoulder straps are attached to the top of the stay frame. Sewing in some load lifters might appeal to me as well if it is possible."

    definitely let me know James! I won't be buying mine until the narrower straps are available, anyway..

    #1490189
    dan mchale
    BPL Member

    @wildlife

    Locale: Cascadia

    At the invitation of Huzefa: As well as doing everything mentioned in the posts above, a frame system gives the pack load consistency and predictability – it will generally be the same fit and will not need adjustment when you take a jacket out for instance. Even a half empty pack with stays will work just fine without ANY special packing – especially if it is some kind of half empty ( or is that half full? ) load that is still weighty. The rule applies to using pads as stays or framesheets as stays etc. in general. The stays or framesheet in a 'well designed' pack, and a well fitted pack, and a pack that is understood by its owner, will do so many effective things that the most un-cost-effective thing a person can do is consider removing them to save weight.

    #1490212
    Huzefa @ Blue Bolt Gear
    Spectator

    @huzefa

    Locale: Himalayas

    Dan, thanks for taking time and sharing your insight to the discussion.

    Lynn, Ben, Nick, anyone else interested in discussion SHOULD read these two links:
    http://www.bushwalking.org.au/FAQ/FAQ_PackTheory.htm
    http://www.aarnpacks.com/features/multifunction.html#fs

    further discussion is meaningless if you dont have basic objective knowledge of pack theory.

    #1490217
    Miguel Arboleda
    BPL Member

    @butuki

    Locale: Kanto Plain, Japan

    Huzefa, thanks for the further information. As with your earlier link, I read and thought about the Aarn pack link a long time ago, when Aarn first started his business online in NZ, and he still only had three packs to offer. I'm not new to any of this information, including reading Dan McHale's site about five years ago when I considered get a McHale pack. I used to be very much into designing and making my own gear, and I read everything I could get my hands on online and off.

    Dan's evaluation of the stays and frame makes perhaps the most sense of anything I've read until now. I still don't see how stays and frames make any measurable difference in terms of keeping a fully-loaded pack from collapsing vertically, since the pack itself would be a stiff, vertically stable object. The pack itself should therefore act as a load transfer unit between the shoulders and the hip belt. Perhaps the more important element would be a stiff and capable hip belt?

    The trend I see in the elements of this discussion is that it is horizontal load transfer that is more important in keeping the contents of the pack both close to the body and safe from sagging, namely the compression straps and the cut of the pack's pattern. By pulling the weight and contents in and stabilizing them the pack doesn't pull away from the body and the load gets nicely transferred between the shoulders and the hips.

    But, as Dan pointed out, a frameless pack that is not full will of course not carry well and sag. The pack cannot then transfer the load between the shoulders and hips, and here is where stays or a frame seem to make a difference. This and the conforming shape that the frame makes. Aarn's diagrams shows the differences between how a fully loaded frameless pack fills out and one with the limiting form of a frame… the limitation is what keeps the pack against one's body.

    #1490228
    David Ure
    Member

    @familyguy

    "I still don't see how stays and frames make any measurable difference in terms of keeping a fully-loaded pack from collapsing vertically, since the pack itself would be a stiff, vertically stable object. The pack itself should therefore act as a load transfer unit between the shoulders and the hip belt."

    Really? Frame collapse refers to the effective torso length changing due to reduced vertical rigidity in the frame, virtual or otherwise. It can depend on fabric and horizontal compression to some degree, but a stiff frame or stays may an enormous difference.

    Measure the torso length of a frameless pack with 20 pounds in it and then add in 5 pound increments for experimentation. Post your results.

    #1490231
    Denis Hazlewood
    BPL Member

    @redleader

    Locale: Northern California

    If your pack has load lifters you probably can't pack it hard enough to resist collapse when you tension the load lifters, without stays of some sort. I had a Golite Trek and had to make a CF back panel to get the pack to keep its torso length. No matter how hard I packed it, and tugged the compression straps, the top would collapse when I set the load lifters. The Trek is a very robust pack and lighter packs might not stand having the compression straps "romped" on, as I did with the Trek.

    That's how it makes a difference.

    #1490246
    dan mchale
    BPL Member

    @wildlife

    Locale: Cascadia

    Miguel: I think you are making too much of the weight of stays. When they are matched to the load they carry rather than being made for a variety of loads, they are more effective than anything else you can do. One way to understand why a pack can never be packed tightly enough to not collapse is to look at a steel cable that you might tighten to walk across. It is almost impossible if not impossible ( I'm not sure these days ) to have a cable strong enough and tight enough that when you walk on it it will not depress. In the same way it is very difficult to stuffa pack tight enough that is can become a structure that can have nuances of adjustment when quarter inches count. And to the degree that a pack is stuffed like a rock, it becomes more and more uncomfortable. In a framed pack the function of load transfer and distribution is separated from the pure bag function and both become more effective. The frame clings to your body and the much more loosely packed bag is easier to dig around in, and whatever you do there does not effect the frame function much. Trying to make the load into a frame reminds me of a raven I saw once that thought it could carry 2 bagels. It would try but could not. I actually watched it put one bagel down to pick up the other and it kept doing it!

    I think all of this anti-stay business and anti-structure stuff is similar to the anti-mechanical romanticism discussed in Zen and the Art of Motorcycle Maintenance. The more complex a sytem is, especially a system that works, the more effort it takes to understand it, but that takes much less effort than trying to understand something that does not work at all. With the whole soft pack thing there is much running around in circles people do. It would be much like someone taking the wheels off of their car and thinking they have accomplished something new and sexy. The soft pack craze will finally go away like it did in the 70s – except for people that call running from food cache to food cache backpacking.

    #1490291
    Nick Gatel
    BPL Member

    @ngatel

    Locale: Southern California

    H –

    Thanks for the links. I had read both of them a while back, but it is always good to refresh one's brain.

    Nice quote from Roger too :)
    "There is a group of fanatics in America who strive to get their base pack weight (not counting food, water or worn clothing) down to 5 lb (2.272 kg) from 6 lb (2.726 kg)."

    There is a certain weight for most people where a frame is a non-issue, perhaps a total weight of 15lbs for me. However, when going above 20lbs, a frame is necessary. Here is the crux of the matter, IMO. Many would say to lighten up and make your trips convenient to re-supply points. And Dan does point that out.

    Now I am not ready to give up my frameless packs, as they have their utility and I am now using them often for 'short' trips. On the other hand, I am not ready to give up my big heavy ones either; an old Kelty Serac with a full-length bag or my Gregory Whitney 95. They are mass-merchandise equipment and work well. I am sure that a McHale would work even better.

    Generally I hike off trail or on old low-use trails, and sometimes need to carry a lot of food and water; especially in the desert. Other than these two packs, my gear has really been lightweight for many years. However, over the past year I have really parred down some items. But no matter what your style, if you need food for a couple weeks or more, you cannot get away from a stout pack and be anywhere near comfortable. I usually avoid people and have only hiked with a partner less than probably a dozen times in more than 40 years of wandering around Mother Earth. I live at the base of Mt San Jacinto, and have pretty much avoided the state wilderness for years, other than ocassional Cactus to Clouds trip during the week when it is empty. Which means that where I am interested in going, there are not going to be convenient re-supply points.

    Thru hiking does not interest me. Sometimes I like to stop for a few days and explore from a base camp. Like Dan, during the 60's and early 70's, I spent a lot of time in the southern Sierras. A favorite trip was to hike from Kernville to Horshoe Meadows and back. My only re-supply was a hike into Lone Pine. And these trips usually included some fishing everyday and exploring. So a big pack with plenty of food was a requirement for me.

    I am mechanically inclined and have spent many years in the automotive industry, so it is easy for me to explain complex automotive systems to others. Dan did a great job explaining the mechanics of frames in layman terms. To be honest, I have not been that interested in exploring the details of how and why a frame works… because I know from experience that with heavier loads, a good frame and hip belt take the sting out of weight. And he explained it in a few well thougt out sentences.

    So the bottom line is that I will be mostly hiking with lightweigt packs without frames or simple stays… but sometimes I will be pulling out the old standbys for trips I want to take and enjoy.

    I hope this doesn't start a debate of lightweight philosphy versus "Old school." I get the ultralight school of thought, and for the most part it is how I now hike. But sometimes other options work better. Try carrying 4 or 5 gallons of water, and you will wish you had an external frame… and you aren't going to cut down the required water in the desert significantly by using an ultralight pack and hiking faster. Plus I don't want to hike fast through a desert, I want to look at it and explore any side canyon that might strike my fancy.

    Good thread, lets keep it on track.

    Dan McHale, thank you for the insight.

    #1490326
    David Ure
    Member

    @familyguy

    Excellent post Dan – thanks for that!

    #1490332
    Miguel Arboleda
    BPL Member

    @butuki

    Locale: Kanto Plain, Japan

    Hello Dan, thanks for the detailed and informative reply. Don't worry, I'm not really disputing whether stays should be used or not because of their weight. I'm merely trying to understand how they work… it just isn't completely intuitive when I look at it carefully. But your explanations make it easy to understand. Thanks.

    #1490383
    Nicolas Costes
    BPL Member

    @ncostes

    I have bought in a sale a TNF pivotal Catalyst 75L +15L backpack, which weight in at 3kg.
    (the idea at the time would be me carrying the gear for 2). Long story short, this idea was stupid.

    Before you kick me out, please have a look at the suspension system which include crossed stays with a pivot at waist level.

    The outcome is a pack which stays level while the hips can move in a much more natural way.
    The belt is heavy and heavy-duty. Cinched tight, the combination of stays, belt and compression straps allow for a very confortable carry.

    For optimal fit, the pack exist in 3 sizes and is also ajustable, hence the complexity and weight (although for optimal transfer, the precise adjustment to back-lemght may be mandatory).

    All in all, I believe that acceptable pack weight is somewhat linked to the weigth to be carried. IMHO, a pack should be less than 10% of the weight to be carried.

    stays or frame aren't necessary for less than 8kg
    are required above 12kg,
    and absolutly mandatory for more than 20kg.

    #1490484
    David Bizup
    Member

    @scouterinahammock

    My G4 experiences match what this thread describes. The only real difference is that you have articles, and experiments, and science whereas I only had sore shoulders!

    Seriously though, the G4 is so big you can not cram enough stuff in there to make it rigid an still have anything resembling a lightweight pack. I would stick in a rolled up blue ccf pad, load my gear, strap on the G4, buckle the hip belt, and start walking. Sure enough, within 5 or 10 minutes the contents would settle, or the rolled pad would crumple, just enough so that pack's weight settled onto my shoulders.

    #1490658
    Richard Matthews
    Member

    @food

    Locale: Colorado Rockies

    David,

    I am glad to hear that I am not alone. I can make the zpacks Blast 32 work great, but I had exactly the same problem you describe with the G4.

    I like the 10% rule that the pack should not weigh more than 10% of the total load.

    #1490849
    Monty Montana
    BPL Member

    @tarasbulba

    Locale: Rocky Mountains

    I also had the same experience with the G4, but I attributed the pack's collapse somewhat to its large size but mostly to the method of packing as recommended by GG. That method was to place the sleeping bag loose in the bottom of the pack and then load the rest of the gear on top of that. Since my bag is down, you guessed it, it would compress after a short time allowing the rest of the gear to settle and shift. Stays definitely would have been helpful for this pack!

    #1490851
    Matt Lutz
    Member

    @citystuckhiker

    Locale: Midwest

    Then I could never carry more than 52 ounces total in my Z1…It works fine with more.

    #1490858
    Devin Montgomery
    BPL Member

    @dsmontgomery

    Locale: one snowball away from big trouble

    >I like the 10% rule that the pack should not weigh more than 10% of the total load.

    I think that means you shouldn't carry less than 52 oz in the Z1. Surely you're not going around with just over 3 lbs? :)

    #1490882
    Mark Hurd
    BPL Member

    @markhurd

    Locale: Willamette Valley

    Devin,

    Actually Matt might mean less than 52 oz.

    Check this gear list for AT yo-yo hiker Brian Doble:

    http://broble.wordpress.com/the-gear/

    Wow!
    -Mark

    #1490934
    Nicolas Costes
    BPL Member

    @ncostes

    In reply to
    "Then I could never carry more than 52 ounces total in my Z1…It works fine with more."

    You have mis-understood my sentence.
    " IMHO, a pack should be less than 10% of the weight to be carried."
    does not mean that total weight should be at most 10 times the weight of the pack.

    It just means than whenever the pack weight is more than 10% of the total load, you could most probably trade in for a lighter pack.

    Why ?
    because, after trying out many packs ranging from 280 gr to 3kg, for carrying between 2kg and 35 kg,
    for ME and MY practices,
    there is a correlation between the weight of a well-designed pack and its ability to carry.

    I am quite happy with my quiver of :
    – black diamond RPM 26 up to 6-8 kg .68 kg
    – Deuter Aircontact 35+10 up to 15 kg 1.7 kg
    – The North Face Snow Leopard 70l up to 25kg 2.3kg
    – The North Face Catalyst Pivotal 75l did not go beyond 25kg 3kg

    So I first choose what I need to transport (weight and volume) and then choose a pack. If the pack is more than 10% of my load , I look to the next size down.

    YET It is true though that a similar rule could also work upward, because a pack frame, hipbelt, shoulder straps are ideally designed for a range of carrying capacity.

    So Ok, I'll bite
    IMHO, with today's innovations, with a goal of full-day walk in varied terrain over many days (my definition of comfort), a pack should be NOT less than 5% of the weight to be carried.

    Have a look at http://www.backpackinglight.com/cgi-bin/backpackinglight/heavyloads.html second table.

    All light packs for heavy loads in the article have a ratio Load/weight ranging from 10 (Lightwave Wildtrek 60) to 19 (ULA Catalyst).

    Meaning, it is today possible to find packs for which
    packs weighs are between 5 and 10% of the load.

    Hence my rule… ;-)

    #1490938
    Huzefa @ Blue Bolt Gear
    Spectator

    @huzefa

    Locale: Himalayas

    >IMHO, with today's innovations, with a goal of full-day walk in varied terrain over many days (my definition of comfort), a pack should be NOT less than 5% of the weight to be carried.

    I suggest you take a look at Zpacks Blast series. The largest pack weights 4.3 ounces / 123 grams. I am sure with 5kgs it is good enough for 20mile days. That puts pack's weight at 2.46% of the load.

    Dont be hasty about forming rules. You never know if sub 1pound internal frame pack with ability to carry 40+ pounds comfortably may be just around the corner.

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