Jam2 Pack: Sleeping Pad as Frame?

Jane,
I can't commment on the BA memory foam pad as I don't have direct experience with the pad but it doesn't look like it will work well with the Jam2. First off, according to the Big Agnes website it is apparently called the Sleeping Giant…beware of using any product labeled 'giant' in conjunction with backpacking. This thing adds almost 3 pounds to your pack weight! That better be one comfortable pad to add that much weight to your back all day long- you'll need it. As an open-cell pad, I don't envision it will add much stability to your Jam2. I would guess it will be nearly impossible to compact the pad down enough to get it into a pad pocket. If you're using it with a 1" or 1.5" self-inflating pad, you might be able to use the self-inflating pad in your Jam2 but I personally find that a closed cell pad works better as a frame than self-inflaters like the Prolite.

I'd suggest a combination of Big Agnes Clearview pad (15oz in full 72 inch length) combined with a closed cell pad like Gossamer Gear's Nightlight torso pad (3.5 oz.). I use the GG Nightlight as the frame for my pack and it works well. It will also serve as decent torso insulation when used on top of the BA Clearview pad, giving you a system that weighs only 18.5 ounces, provides a sturdy 'virtual pack frame', and provides a full 72" pad length with 2.5" inches of cushioning. This system should also cost about the same as the memory foam pad by itself.

Russell,

In my case, I have the Large Size Jam2, based on the many comments on the BPL forums that GoLite seems to run half to one size too small vs. what their recommendations.

I am only 5'6", but I have a torso length of something like 18". (I am not a big guy by any means).

I could not imagine using a smaller pack.

I agree with you that the fit is very important above all else and I have been very happy with my Gregory Z55, which fits me perfectly.

My observation is that the Jam2 does not have the pack strap on the shoulders that pulls the top of the back back towards the upper back- hence why it hangs off my shoulders.

My friend has a Granite Gear Vapor Trail and I noticed that his does the same thing to a lesser extent than the Jam2.

Perhaps the torso length is still and issue with the Jam2, even in the large size.

I find that I have to loosen the shoulder straps so that the load is firmly on my hips and not my shoulders.

Granted, I was carrying about 26 lbs, which is the upper limit of what it can carry.

Despite what the GoLite website says, anything over 27 lbs, I would rather carry my "heavier" Z55.

Just some observations on my limited experience trying to transition to a frameless backpack.

-Tony

Tony,

First, a disclaimer- I've never used or worn the Jam2.

Second, I'd trust the manufacturer's sizing recommendations. The Jam2 large is made to fit torso lengths of 19.5" and up. It seems to me that if the pack is falling away from your shoulder blades that having a pack which is 'too tall' for you would just exacerbate this problem by giving the pack too much slack as it sits on your back, pushing it up higher on your back when the hip belt is cinched up tightly in its proper location.

I haven't read the comments you have about the Jam2 being too small but if your pack isn't fitting right, maybe those comments are off-base, at least where your ideal pack fit is concerned. Just a thought. I'd give the medium a shot if you can…

I got a Z Rest to go with mine. It has a lot of miles on it. I use a 3/4" foam pad cut to shape when I take the hammock. I knkow some folks use election signs and cut them to shape. I tried that, but it weighed the same as the foam pad and I could not muli-use the sign. The foam pad is a sit pad when hammocking. I did some mods to my jam2 and I love that pack.

Russell,

Actually, I think that if the torso length of the Jam2 was "longer" I would have less of a problem.

I am finding that because the pack is not resting fully on my hips, I need to loosen up the shoulder straps to allow the pack to slide back away from my shoulder blades.

I think that if the pack was longer/taller, it would rest fully on my hips and I would not have to slacken the shoulder straps.

Anyone else out there have this issue or is this just normal for a frameless pack?

P.S. Ben: I tried folding my thermarest pad up in an L shape and it did solve the problem of the pack crimping in the midback area. The only issue that I am finding is that the pack is hanging off my shoulder blades by about 4 to 5 inches. I have hiked 18 miles over 3 days using it like this. It is not uncomfortable, but it certainly is different from what I am used to with my Z55 and having the whole pack glued to my back securely.

-Tony

Tony:

As a comparison, below is a photo of Joe Valesko — owner of Z Pack — modeling his own product:

As you can tell, the top part of the pack actually leans back away from him — something you never see with the more rigid internal frames fitted with top load lifters. OTOH, you can also see that the rest of the pack hugs closely to his back, and the thin webbing waistbelt actually do hlep to transfer weight onto the hips.

If in doubt, load up your pack completely, put it on, adjust everything, then take two photos — side and back profiles — and post. I bet Jam 2 users will be better able to assess and advise.

Tony, A frameless pack will never carry the same a a framed pack. You can transfer alot of weight to the hips but you will always have some on the shoulders. It can be very effective and comfortable , especially if the weight is kept under 20 lbs. How you load the stuff in the pack will also have a great impact on a frameless pack. Experiment w/ your heavy and light items in various locations to see what feels best. I like to put some semi-light stuff on the bottom (like clothes bag) then the heavy dense (food bag) close to the small of my back ,then lighter stuff above. In my Jam I actually found it more comfortable when I removed the foam frame sheet and used my 3 times folded over Montbell 35" inflatable pad as the frame sheet next to my back. I slightly inflate it to help keep it rigid. Works like a charm!

Russell, thanks for the suggestion. Sorry for the lag in reply-time. The weight does sound awfully more manageable, as does the packability. At the end of the day I just want to be sure I sleep well and the choices and combo possibilities seem endless! The budget, however, never seems to be. (sigh)

Had to edit – I just picked up two BA Clearview pads at BackCountry.com for $9.95 each! The last two in stock. Woo hoo! Budget AND backbone should be happy. Thanks again Russell.