This is my latest in a long line of home made External Pack Frames. This one uses a few parts from a Mountain Hardwear Harrier pack.

I made a new hip belt that is mostly foam stabilized with thin plastic sheet.

The shoulder straps are also new and made from a very strong and very special Cuben Fiber (6.25 ounces per sq yard) by itself. The shoulder strap system is very adjustable.

The Scandium tubes are from the Harrier Frame. They attach to the frame and the hip belt, transfer load to the hip belt and provide torsional compliance so the pack can move with your body. The Scandium tubes also offer vertical rigidity.

The modified Frame weighs 17.67 ounces. The stock Harrier frame weighted 55.65 ounces.

The stock Harrier pack bag at 3600 cubic inches weighs 34.86 ounces empty and I will make a new bag about the same size out of Cuben Fiber. The new Cuben Fiber Pack Bag will not have all the zippers and junk the old bag does but will connect to the frame the same way. That makes changing the size of the pack bag easy.

I am using the stock Harrier pack bag for testing the frame. The bag (with stuff in it) and frame weigh 21 pounds. I am walking 2 miles twice a day to test the frame. I will add weight over time till I get up around 30 pounds. I have carried this set-up for 10 miles so far. I have tweaked the setup a bit and it seems to be working well.

If this new frame and bag works out it might be used for something like a long AT hike next year.

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Ultralight Skunk Works is back in action (or at least making it public anyway). Bill, good to see you're up to your old tricks and haven't given up on either the external frame idea or a long AT hike.

Do the vertical elements have flex to them or are they rigid at that particular curvature? The Harrier frame is very unique looking. I had to research it a bit more to get a feel for what you had and hadn't done to it.

This particular design is a far cry from some of the more squar-ish externals I've seen you work on in the past. And it lacks the wacky whiffle ball hipbelt. Keep up the good work, I look forward to seeing the cuben bag and hearing the combined weight.

Hi Sam,

One of my problems with a long AT hike or any long hike has been the time between my Cancer follow-up exams. I have a bladder exam every three months forever but the goods news is no cancer in my bladder for a bit over two years now. The follow-up exams in my throat area have just gone to three months also. I just went over two years since all my treatment and the necessary surgery from the throat cancer was over. My next two exams are mid-January and both are on the same day. If all goes well on those two exams I will have three months till the next ones. I asked if I could stretch them to four plus months. There comments were lets see how my bladder looks in January first.

Frame question:
Q-1. Do the vertical elements have flex to them or are they rigid at that particular curvature?
A-1. The vertical elements do not flex. They are rigid or maybe a better way to say it is they are bent to the shape you see. The curved piece above the hip belt is also bent in the shape you see.

I have wanted a Harrier pack to play with since they came out. I was able to buy this one at a really good discount last December. I tried two version of a frame with straight tubes but that didn't work. I made the aluminum fittings for the side tubes a long time ago. Sometimes you just have to let something sit awhile and think about it. Last week I decided I was ready to give it another try using as much of the Harrier parts as I could. What you are looking at is really version three.


The "squar-ish externals" were driven by what I had to work with. They all worked but were never really were I wanted to go with this.

Watch what you say about "the wacky whiffle ball hipbelt". If you go back and read what I had to say you will see that it even made me laugh. It did however, prove the point I was trying to make.

Bill,

Your product line has grown increasingly sophisticated over the years, and this external rendition is no exception. I applaud your creativity and persistent development.

As a user of a McHale suspended K2 frame (heavy by UL standard and comfortable carrying considerable weight), I maintain a bias toward hip weight transfer and a relatively circulated, dry back while trail hiking. This frame looks quite comfortable.

I appreciate your ( and others, as documented in past forum discussions of external frames) effort to transfer weight toward the sides of the hips, and was struck (by comparison to a McHale) with the fastening of tube to belt. An old video from McHale Packs shows a frame member fastened to the belt via a heavy nylon tab sewn to and hanging from the bottom edge of the hip belt. I think this fastening mechanism was unique to the heavier CM series packs, and the frame/tab connection occurred more toward the back of the belt. There are obviously differences, and certainly more that I'm unaware of. Nevertheless, I was impressed by the tab, hanging from a belt that seemingly retained its flexibility in contacting and wrapping around the hips.

Given design issues between the CM line and your external, I can imagine frame/belt fastening differences, but I would be glad to send the explanatory video if Mchale no longer uses it, and/or if you have not seen it.

Nice work, Bill.

Hi "skots",

Thanks for the nice comments.

I agree with you about the McHale Packs. I really like his packs but as you said they are heavy. As a Super Ultra Light hiker I just don't need a pack made to carry a lot of weight. I do think I would buy one of the smaller "Summit" packs like Ryan is wearing in a few of his trip photos if he ever decided to sell that pack again and if was a bit on the light side. McHale has developed many great ideas in his pack systems and I am sure they carry well with a heavy load. I have never seen the video you talk about and don't think I ever saw the fastening mechanism you are referring to. I would like to see the video.

The way I attached the tubes to my hip belt is more or less a direct copy of how Mountain Hardwear did it for the Harrier pack. My hip belt fittings are a lot lighter and I did add something that I think makes it a bit more adjustable.

Bill, what an elegant design you've created. Thanks for sharing this with us.

Looking at your hipbelt, I'm curious about the material. Is that a closed cell foam? How do you expect it to wear with the daily friction against your clothes?

Thanks.

Hi Phil,

Yes, it is from a blue sleeping pad. I have used this material on other hip belts and shoulder straps before without any problems. It has a slick surface and I have never noticed a friction problem with the sleeping pad material.
All the connection points have something to reinforce them on both sides and the outside reinforcing material goes almost the full length of the hip belt. It is clear and hard to notice. If I have any problems I would just move the clear material to the inside of the hip belt.

I am putting 4 miles a day on the frame with 21 pounds in the pack so time will tell on the wear question. The weight will go up in the pack over time till I get up to about 30 pounds. I don't think I would ever need to carry that much weight unless I was carrying a lot of food or water.

Bill, that is very interesting using the blue sleeping pad as a hipbelt pad. Every single pack (of a dozen or more) that I've owned has nylon fabric on the hipbelt padding. I enjoy seeing your fresh look at even the little details. I would not have expected a foam sleeping pad to have that much durability. Hope you enjoy that pack greatly on your upcoming AT walk.

Bill,

What's the value in the cuben fiber straps in terms of it's weight to strength ratio compared with other more common materials from a price standpoint? So, strength to weight to price of the cuben compared to say dyneema?

Hi Sam,
I am not sure how to answer your question. I have a bit of Dyneema from three difference places. Some of what Thru-Hiker was selling, some of what OWF was selling and the third was from Quest and they called it "Spectra Ripstop.

I didn't use my Dyneema / Spectra Ripstop because I didn't think it would be strong enough to work the way I used the Cuben.

The Cuben product that I used for my shoulder straps is a lot stronger than any of the above three. I tried to call Cuben today but was unable to talk to Chris and ask about availability of this product. I have had mine for a long time. I think the price at the time I got mine was something like $32 a yard. To me this stuff looks more like full spectra. I know it is really strong

This morning I got lucky and made what I think is my last adjustment to the Scandium Tube / Hip Belt spacing. I found that "sweet spot" just at the perfect place in the small of my back for the hip belt. My 2 mile walk was so great I walked 3 times today. I will try and continue to walk 3 times each day.

All parts of the frame are holding up well so far. Makes me want to go for a 8 to 10 day hike and see how it works on the trail.

Thursday I will start working on the new Cuben Pack Bag. It will be about as large as the Mountain Hardwear Bag so I don't have to compress my insulated things a lot. I will probability end up making 2 bags for this frame. The second bag will be a bit smaller for a warmer weather gear list.

Bill,

I’ve been unable to locate my copy of the video that I referred to above, but I did find that copies are still available here http://www.mchalepacks.com/video/index.htm for a token fee.

While perusing the site, I also found a picture of the belt/frame fastening http://www.mchalepacks.com/ultralight/Detail%20Hi%20Rez%20Pages/Used%20Pack%20Buying%20Guide.htm that I was attempting to describe. I believe that the two interior bolts/rivets in the photo represent the frame/belt fastening, and that the lettering is written near the bottom of the belt interior, at the back center. From these two fasteners the belt is free to conform to the wearer. I have no idea about belt construction or how /if the nylon tab is fastened or reinforced beyond the visible stitching, but considering the pack’s weight capacities, the method appears awash in simplicity.

At any rate, I’m glad to read of your progress in fine-tuning your pack, and look forward to completion of the bag.