Proposal for a novel backpack component: Movable Lumbar Pad

[Nenta WAKO, Dr.Eng.]

Companion forum thread to: Proposal for a novel backpack component: Movable Lumbar Pad

When you think about an effective backpack load distribution to the lower back, what will you focus on?
I thought it will be achieved if lumbar pad is well fitted to the lower back keeping its fitting state dynamically…

[John S.]

Thanks for sharing.

[John “Jay” Menna]

This is fascinating stuff.  You mentioned that it’s part of your PhD thesis?     Do you have a URL where it was published?

[Scott Nelson]

This reminds me of the old North Face Black Magic backpack.  It had a external frame that connected to the hipbelt via a flexing plastic strut.  That allowed the belt to flex as a hiker walked.  The pack weighted a ton as I recall.  It never caught on and North Face was a small player in the pack market behind Kelly, JanSport, and the new internal frame packs.

The connection point between the hip belt and back panel of the pack would have to be strong.  I wonder if a single center strap from the bottom seam of the pack body to a floating hipbelt would achieve the same movement? Would having the bottom of the shoulder straps anchor into the hipbelt help or hurt this movement?

interesting idea,

Scott

 

[Nenta WAKO, Dr.Eng.]

John S,

It’s my pleasure!  👍

[Nenta WAKO, Dr.Eng.]

Jay,

Thank you for your interest in my research.
Sorry, my doctoral thesis is only published in Japanese version; The captions of the figures are in English, though. You can access it on the link below.

https://waseda.repo.nii.ac.jp/index.php?action=repository_view_main_item_detail&item_id=65271&item_no=1&page_id=13&block_id=21

[Nenta WAKO, Dr.Eng.]

Scott,

Thank you for your comment.
I checked the photos of TNF Black Magic. It is similar to a rough concept.
And as you mentioned, the connector should be strong. In our product, the axis of the connector is made of hard steel. And the weight of the pad ASSY is about 300 grams.

Regarding your idea, connecting the hip belt with a single center strap might be a simple solution for only sewing. But its motion range should be precisely set with consideration of the fabric deformation.
And in my concept, the pack body should integrate thorax so that it doesn’t interrupt upper body motions, and the load distributes dynamic to the pelvis with an independent movement.

[Jason Brooks]

Doesn’t any kind of hipbelt impede your movement? I find relatively good support without impeding of movement by having runnig style shoulder straps that support off the ribcage. I guess that only works to a certain weight, though. Aarn Packs has one of the better designs incorporating a hipbelt by having pass through sliding shoulder straps which allow the load to rotate freely with your hips even though it is still weighting them down.

[Nenta WAKO, Dr.Eng.]

Jason,

I think if the hip belt connects the lumbar pad that I developed (not connects the pack body), the pelvic rotation was less interrupted. I don’t know about the structure about Aarn packs. But I think that the pack body should be integrated with thorax (not pelvis) in order to avoid the effect of the pack lean. And hip belt needs to absorb ±2cm of the sideway relative displacement.

[peter v]

that is a very interesting concept you have there. i am sure it is valid, and efficiency can be gained.
i use both a Aarn backpack with it’s extreme use of isolating elements, and a McHale pack, with it’s industrially severe structure. they both carry well in their intended ranges.

along the lines of the Aarn, with all it’s sliding parts,  and straps, and tubes, and channels, and all of the details that let it carry so joyously well, there is a cost. that cost is that one really needs to be aware when putting it on that everything is correct. it is for example, quite easy to toss an arm thru the wrong place, and thence be on the incorrect side of a strap. although super comfortable at lighter weights, the system is unworkable at higher weights over the course of a long trip.

Aarn has for several decades been working effectively towards greater efficiency by proper balancing loads front to back, and by allowing several areas of pack attachment to be zero-sum, so as one side may tighten, the opposite loosens.

for what it’s worth ; in light of my experience, your theory is correct on that some energy is consumed when the pack locks the torso in rotation. under enough load (expedition type loads) the locking will go so far as to change ones walking gait. so that might seem not ideal. however … it has also happened that when using a pack with a nice comfortable rotationaly isolated lumbar support, that situations occur where the mass of the pack decides that it wants to go off on it’s own, as if i had given it permission. those situations can be dangerous in a very immediate way. example ; rock hopping across a creek, the load shifts and throws off the aim of my leading foot. into the river i then go. possibly slipping off of a rock. it’s just not a safe experience.

i suspect the rotating belt would be very nice up to about 20 kilos, and after that it might increasingly become a liability. or perhaps the load-shifting is a combination of both the belt rotation coupled with the shoulder strap isolation system. i don’t know.

carrying efficiency is not perhaps so simple as it looks sometimes.

[Steve Thompson]

Dan McHale with his critical mass lumbar pad was probably first to provide lumber pad adjustability.  Had about 1/2″ range up and down, could tighter or loosen the tension, and could change the thickness.  Being able to adjust the lumbar pad independently of the hipbelt enables optimal loading/carrying the pack on the sacrum as we are all built just a little bit different.

[Author]

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