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Pack Dimension Question - Urgent
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Elisa Umpierre
(eliump) - MLife

Locale: Midwest
Pack Dimension Question - Urgent on 03/31/2014 08:58:40 MDT Print View

Hi everyone. Really looking for some input here. I'm in communications with Chris Zimmer right now to have a custom pack built for me. I initially ordered and received (in lightning speed, I might add) a custom hybrid-cuben ULA Circuit pack in a size small, but quickly determined that the 2400" cu inch main compartment does not have enough volume for me to carry my gear and 7 days of food. I'll be doing a cold weather (snow on the ground) hike, so I need to take my insulating layers along.

I'm considering a Zimmerbuilt pack dimension of 14" x 8.75" x 22" for a total of 2,695 cu inches (the roll top closure would be in addition to these dimensions). Like the Circuit, I'll have a front, expandable mesh pocket on the front of the pack, two side pockets, two hip belt pockets and one shoulder strap pocket as well. I'm really trying to avoid having the top of a fully loaded pack pressing into the back of my head with the least little head tilt back. Does anyone see a weight distribution or other problem with the pack as described? Thanks.


(I have an 18" torso)

David Chenault
(DaveC) - BPL Staff - F

Locale: Crown of the Continent
Re: Pack Dimension Question - Urgent on 03/31/2014 09:39:21 MDT Print View

"14" x 8.75" x 22" for a total of 2,695 cu inches"

Those dimensions may add up to 2700 on paper, but they'll make for a pack about the size of most makers 50-60 liter bags. Dimensionally it should be quite roomy.

14" is pretty wide. If you have a narrow torso/shoulders you might find it restricts arm movement. Depending on the suspension and back panel design, Chris might be able to taper to 10" up near your shoulders, while making the side panels wider to maintain the same overall circumference top to bottom. This will tend to make the bottom part wider but flatter (i.e. closer to your body), with the upper part a bit narrower and fatter. I like how this design carries, myself.

The head space issue will be a function of the load height, bag design, and how you load it. With a fairly large bag, odds are you'll be able to keep the bag from getting too tall. A lid or top strap will help compress and pull back the top when it does get huge.

Matt Dirksen
(NamelessWay) - MLife

Locale: Mid Atlantic
Re: Pack Dimension Question - Urgent on 03/31/2014 09:47:51 MDT Print View

Hi Elisa,

Your post raises a few questions/thoughts for me:
1) A 60 liter bag sounds like a good size, but you sure adding 5 extra liters to the pack size will ultimately make the difference you are looking for? (just making sure - that's all). Are there accessories you can attach to accommodate for the extra 5 liters instead? Is there a 60L bag nearby/on-hand/borrow that you can fill with your gear, just to make sure?

2) Since you are essentially re-designing the bag, are you designing for the "exception", or the "norm"? Is this 60L bag a better tool for you in the long run than the 40L?

3)Internal frames are very sensitive to where items go as much as what they are. Do you have a strategy for where things are going to go? To avoid the the "pressing" you describe, you could possilby distribute your "compressible" items more vertically, instead of all at the bottom. The only downside to this method is you run the risk of sending some of the heavier items further out away from the back (and creating more impact force on the shoulders & hips.) However, if these shift to the sides of the pack, the impact force may be reduced (like water in bottles in side pockets).

4) Don't forget that with a little creativity, one can "externalize" a lot of gear on an internal frame in a pinch, as long as the bag has some well-located straps & loops. A couple of stuff sacks with sewn in tieouts could be useful as well.

hope this helps.


Elisa Umpierre
(eliump) - MLife

Locale: Midwest
Pack Dimensions on 03/31/2014 10:14:43 MDT Print View

Thank you, both David and Matt, for your feedback.

David, I was wondering about the possibility of tapering as you described, but thought perhaps I was being odd with that possibility. Nice to see I wasn't so off when I came up with the idea initially. Tapering is something I'll ask Chris about.

Matt, as I suspect many of us on this site suffer from, I do believe I'm addicted to gear :-) I don't consider being so a bad thing, however. I can pay for it, I'm not out gambling, drugging or drinking my money away and learning about/buying/using cool gear is a great hobby.

I have several packs from a gigantic, ultra-heavy Dana Designs Terraplane all the way down to my small Gregory hydration pack. I did the 500 mile Camino de Santiago with the Dana (first time I ever got into and did a long distance hike back in 2003. The pack was very sound but WAY too heavy and big), 125 miles on my GoLite Infinity Pack (this is a 50 liter pack, but it took a beating on the AT and needed to be sent in for refurbishing. I sent the pack in on February 15th and have not yet received word as to when I'd get the pack back. The size was great and the pack was super comfortable, but I was hiking with another person so the tent (TT Squall) and cook set were split between us - and it was summer). I did the Tour du Mont Blanc using my REI Venturi 30L pack. Just right in every way for this trip.

Using the external pockets, I think I could make a 50L bag work for this trip (Thru hike of the Superior Hiking Trail to begin May 2nd). Northern MN just this morning got another 12"+ of snow dumped on top of a very deep snow base as it was. I'm sure I'll be hiking snowy trails, etc. The pack that Chris is building is specific to this trip, but, of course, I would love to be able to continue using it on other trips as well. Thanks again for your thoughtful replies.


Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Pack Dimensions on 03/31/2014 12:34:10 MDT Print View

When I think about over-snow travel, I think about cross country skis. Others may think about snowshoes or else just boots.

For cross country skiing, you want a backpack that is slightly narrow. Because of the way our arms swing, a narrow backpack causes less conflict.

Also, when some people specify a backpack volume, some refer to the total volume for the main compartment plus the external pockets. That can be a bit misleading.


Elisa Umpierre
(eliump) - MLife

Locale: Midwest
Answers to Posts on 03/31/2014 12:57:04 MDT Print View

Thanks Val and BG.

I don't think the snow cover on the trail will be consistent enough to use snow shoes or cc skis. Goog, God, I sure hope not. I'll either be using my WP Keen mids or my Hoke One One shoes with a gore-tex sock. Might have to add yak trax as well for some spots.

Yes. I've recently learned that the capacity of packs includes the outer pockets, etc. The cubic inches I want that are listed earlier is of the main compartment. The additional pockets will be exactly that - additional space.

Fortunately, my experience level to this point had my hybrid cuben 2400 Circuit weighing in at 15.5 pounds with EVERYTHING inside of it (including a 2 pound personal safety item many don't carry) except the food and a full water bottle. I don't need too much space to fit 7 days of primarily "add water" meals.

If anyone is curious, I'll post my gear list if you want.