Alternate back pads for MYOG arc packs

[Nick Smolinske]

I’ve been meaning to write about this for a while and a recent thread in the Gear forum sparked me to finally do it. These are two attempts at making alternate back pads for my MYOG packs using the arc blast frame.

The first option is very well tested with quite a few trips on it:

The pad is made with 3d mesh, 1/4″ foam and Xpac. The webbing that the cord ties into (actually folded over hypalon rather than webbing) is sewn ONLY to the xpac – not through the foam. The foam sticks out a bit on each side so that it’s wider than my shoulder blades.

The effect is a nice, comfy foam pad that doesn’t irritate my shoulder blades at all. It sits pretty much centered on the blades and the rest of the pack does not touch my back.

The second back pad I’ve made is for a prototype lightweight canyoneering pack, and it’s a very different style – back to mesh, but where the webbing is not continuous through the pad, but rather sewn onto each end. There are reinforcement patches to spread the load.

Then the edges of the pad taper down to another piece of webbing that goes behind the stays and gives the pad a curved edge. I tried to make it adjustable but that didn’t work well so I just found the right length through trial and error. Here’s a photo:

So far the pad is pretty comfy (one 4-day trip on it) but it remains to be seen how well it works in the long term. There are some potential failures, namely the mesh ripping or stretching along the lines of tension. But so far the reinforcement patches seem to be doing a good job of spreading the load. I used heavy duty polyester mesh so that should help with the stretching (and hopefully be durable enough for canyoneering).

That said, I’m going to hit that pack with the seam ripper, because I don’t like how I did the frame on it. It’s a rectangle made from Quest tent poles and 90 degree connectors. JB weld holds the connectors and the horizontal bars together to prevent frame twist. The vertical poles are cold set with about a 1.5″ deflection (tensioned to 2″ deflection with the back pad).

It’s my first time trying to put a piece of the frame across the back of the hip belt and I am not a fan of it, at least the design I came up with. My previous packs have had the bottom of the two stays not connected and that is much more comfortable. With the connected one I can feel the hipbelt changing the natural motion of my pelvis when it’s cinched tight. That is very disconcerting and possibly a recipe for an injury if I were to use it long term. So back to the drawing board on that design.

[Sam G]

On the first Pad setup, is this something that could be made to make with the stock zPacks backing, or does it only replace it? I do like that idea for sure.

[Nick Smolinske]

Sam,

My version is a replacement, but now that I think about it you could make a modification instead. As long as you have uncompressed foam about 1/4″ thick, running across the whole panel and overlapping off each end about half an inch, I think it will be as comfortable as what I made and probably easier to make.

Although how to attach it to the mesh in a secure way without sewing through the foam is an open question. I will leave that to someone else to figure out, I do not have the time.

[Nathan Meyerson]

Looking good Nick!

Hows that 16oz Hypalon holding up for the backpanel carbon bar attachments?

Been wanting to make one of these with some 1/2″ x 1/8″ Carbon Bar I have lying around.

I dig the floating waistbelt attachment on the D40 pack.

How is the liteskin pack waistbelt attached?

Are those low profile cam buckles or triglides tensioning the webbing on the more recent pack?

Been playing around hacking thrift store external frame packs to more modern (lower center of gravity) load haulers. Tons of fun and they carry great, but these packs are usually in the 3lb range.

Bummer you’re gonna shred that liteskin pack, I’m curious how that material would hold up canyoneering.

[Nick Smolinske]

Nathan,

The 16 oz hypalon is working pretty well. Although I have doubled it up and added wear patches of heavier fabrics at the very bottom and top of the stays – I was worried about wear on my original D40 pack, this is version 2.0.

The floating waistbelt is great, the LiteSkin pack has a very similar belt. On the D40 pack the belt is attached in two places, right at the bottom of each stay. Attached an inch or so above the bottom of the foam so the stays don’t dig into my butt. On the LiteSkin pack there’s a 5 or 6 inch wide strip of hypalon in the center, that runs from the hipbelt under the bottom of the frame and attaches to the pack. So the pack hangs off of that. But as I said above I’m not a big fan of the design. On the D40 pack you can see the bottom-most horizontal stay runs near the top of the hipbelt rather than near the bottom, and that seems to be enough to make a difference. Also the fact that the hipbelt is only attached in those two places may make for a more flexible and comfortable carry.

I won’t be shredding the entire pack, I’ll just remove the back panel and replace it with a new one to accommodate the new frame, once I work out the details and find the time. So it will still get a good canyoneering test. Although to be honest, I think 1000d cordura is a better choice unless you are really trying to go UL. Or D40. It remains to be seen how well LiteSkin holds up but I expect it to be ok, not great from what I’ve seen so far.

Which brings to mind the question of what “abrasion” really means. I do like the LiteSkin stuff, but it seems to me that the D40 is more abrasion resistant in practical terms. Despite the D40 having a lower abrasion result on the spec sheet. I suspect that D40 would be a better choice for canyoneering than LiteSkin, at about the same weight.

On the trampoline, the bottom of the mesh panel has triglides. The top has a ladder lock buckle. The webbing used is the venom dyneema webbing from RBTR – I wanted something that would not stretch at all when wet.

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