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Review: Big Agnes Insulated AXL Pad || Very light & comfy, not very warm

My cowboy camp in upper Conness Creek on the Yosemite High Route in August. (My quilt was air-drying in a nearby bush.) Nighttime temps were normally in the high-30’s/low-40’s, and I found the Insulated AXL to be sufficiently warm.

Until last spring, Big Agnes had no sleeping pads in its line that interested me. The pads looked comfortable, but they were considerably heavier than my time-tested Therm-A-Rest NeoAir XLite ($170, 12 oz).

But with the AXL sleeping pad, Big Agnes caught my attention — its weight and thickness looked promising. The AXL comes in two flavors:

The listed prices and weights above are for the 20″ x 72″ mummy version. Both pads are also available in rectangular shapes: a wide AXL (25 x 72); and petite, regular, regular-wide, and long-wide Insulated AXL (20 x 66, 20 x 72, 25 x 72, and 25 x 78).

This year I have slept on the Insulated AXL (as a normal ground pad and as under-insulation in a hammock) for about 30 nights in southern Utah, the Colorado Rockies, and High Sierra. Big Agnes sent me two pads, and I loaned out the other to my wife and to guided clients for additional feedback.

Two thumbs up, Paul reports after a night on the Insulated AXL in Sequoia-Kings Canyon National Park in late-September, which is about its seasonal limit in the Mountain West.

Review: Big Agnes Insulated AXL Sleeping Pad

The Big Agnes Insulated AXL Air is a very lightweight and comfortable sleeping pad, and is best suited for weight-conscious backpackers who want quality sleep in the backcountry.

The 20″ x 72″ rectangular Insulated AXL specs at just 11.9 oz (although mine weighs 12.6 oz, or 12.9 oz with the included stuff sack). In its factory packaging, it’s about the size of a 1-liter bottle — although, it’s difficult (and not worth the time, IMO) to pack it that tightly again. I roll mine full-width, fold it in half, and keep it in a larger stuff sack.

When rolled tightly, the Insulated AXL is about he size of a 1-liter bottle.

Of the pads that compete with the Insulated AXL’s size and weight, none match its thickness (3.25 to 3.75 inches) or have over-sized outer tubes that help to cradle the sleeper — it’s a subtle feature, but helpful.

The Insulated AXL is reasonably quiet, avoiding the “potato chip bag” sensation of other leading pads. On my first trip out with it, on which I also used a new tent, it produced a sound similar to rubbing balloons together. But I have not noticed it since, leading me to think that it was the new pad, the new tent floor, or the combination of the two materials.

The Insulated AXL is appropriate for 3-season conditions, but not for shoulder seasons and definitely not for winter. Personally, I found the Insulated AXL to be amply warm in temperatures of 40+ (4+ C) and to be acceptable in temperatures of 30+ (0+ C) so long as I took other measures to maximize my nighttime warmth (e.g. bring a warm sleeping bag, pick a soft campsite, sleep in my insulated clothing, and eat and hydrate well before bed).

His and her pads inside a Big Agnes Tiger Wall 3. The Insulated AXL is normally quiet, but not on this trip in southern Utah — it sounded like two balloons being rubbed together. I’m uncertain the cause: new pads, a new tent, or a combination of the two.

Key specs

  • Rated to 32 degrees
  • 3.75-inch thick outer tubes, 3.25-inch inner
  • 20d high-tenacity rip-stop nylon top and bottom shell
  • Primaloft Silver synthetic insulation laminated to a Mylar sheet
  • Five SKU’s, varying with shape, length, and width
  • 10.6 to 15.9 oz, depending on the size
  • $160 to $250, depending on the size

My 20 x 72 Insulated AXL came in at 12.6 oz (+0.3 oz for the stuff sack), over its spec weight by 0.7 oz.

The competition

For those who prioritize pack weight and volume, the Insulated AXL is one of two 3-season pads that I can personally recommend, along with the aforementioned XLite.

On paper, other contenders include the:

Big Agnes Insulated AXL vs Therm-A-Rest NeoAir XLite

The Insulated AXL is more comfortable than the XLite. It’s thicker and has oversized outside tubes, and it’s quieter.

But the XLite is warmer. I do not hesitate in using the XLite on elk hunting trips in the Colorado Rockies in November, or even on winter trips when I must sleep on snow. I would not use the Insulated AXL beyond 3-season conditions.

If your backpacking season extends into colder months, the XLite may cover you completely. Whereas if you were to purchase the Insulated AXL, you’d need an additional cold-weather pad.

Warmth

When the Insulated AXL was first released, Big Agnes recommended a usable range of 15 to 35 degrees F (-9 to 2 C) on its website and product packaging. Based on my experience I believe these guidelines were generous, and unfortunately REI — which was the exclusive distributor of the AXL and Insulated AXL when it was first released — hyped expectations even more by advertising it simply as a 15-degree pad.

Customers were not pleased, and revenged their sleepless nights by giving the Insulated AXL many 1-star reviews.

Per the manufacturer website, currently the Insulated AXL is “rated to 32 degrees.” There is no discussion of how Big Agnes arrived at this number, or exactly what it means — i.e. Is 32 degrees a comfort limit, or a lower bound? And under what conditions (e.g. sleeping bag temperature rating, shelter type, ground surface composition) would this rating apply?

What is the R-value of the Insulated AXL?

Big Agnes does not publish (and, from what I can tell, does not test in-house) R-values, which is a precise measure of a pad’s resistance to conductive heat transfer. These values are useful in comparing the absolute and relative warmth of a sleeping pad.

Why? Len Zanni, a co-owner of Big Agnes, explained to me in an email that, “We believe [R-values] are still not consistent. Different brands use different testing methods. Until there is a standard (we’re involved in industry efforts here) we’re trying to guide users into the right pads using recommended season and a season spectrum guide (on product packaging).”

Why is the Insulated AXL not very warm?

To understand why the Insulated AXL is less warm than other pads, it’s useful to understand its construction. The pad is kind of built like a sandwich:

  • The bread: 20d high-tenacity rip-stop nylon; and,
  • The meat (or the vegies, for my Boulder readers): Primaloft Silver synthetic insulation laminated to a Mylar sheet.

Primaloft Silver is available in different weights (e.g. 30, 60, maybe 100 grams per square meter). Big Agnes will not share the insulation weight used in the Insulated AXL, which it considers proprietary information. But based on what I can feel and see, I suspect that the lightest version of Primaloft Silver was used. It could be quickly confirmed, using basic geometry formulas and knowing that there is a 1.0-ounce difference between the 20″ x 72″ mummy AXL and Insulated AXL (which are otherwise exactly the same).

Not only did it use a very lightweight insulation, but Big Agnes also had to:

  • Cut holes in the insulation, so that the bottom and top sheets could be quilted together; and,
  • Cut the insulation in two (one half insulates the upper body; the other half, the lower body), creating a gap between these sheets.

Big Agnes was also unable to attach the insulation to the edges of the pad, leaving an insulation-less gap around its perimeter.

With all of these holes and gaps, body-warmed air and ground-cooled air can circulate too easily, especially with active sleepers. Warmer pads more effectively trap air.

If Big Agnes could have produced a warmer pad without affecting the weight or price of the Insulated AXL, I’m sure that it would have. This is simply the cost of a 12-oz pad that is nearly four inches thick.

The Insulated AXL is widely reported to offer limited warmth. I speculate that there are two reasons: the use of a very lightweight/thin version of Primaloft Silver insulation (which is laminated to a Mylar sheet), and multiple holes in the insulation and Mylar that allow circulation within the pad of body-warmed and ground-cooled air.

Durability

My Insulated AXL has not yet sprung a leak. But I’m careful with it. YMMV.

A client managed to break the valve on one of my pads. I didn’t hear an explanation, but I bet it happened while rolling it up — if the valve flap is not in a “closed” position, it could get caught between the sheets and be torn off.

Thankfully, the damaged pad is still usable: I blow it up completely and cap it as quickly as I can. About 25 percent of the air is lost, but that’s still plenty — and, in fact, that level of inflation is just about perfect.

I did not get an explanation, but a client broke the valve on the left pad. Notice that the valve flap (it’s violet) is missing.

Inflation and deflation

It’s a chore to blow up the Insulated AXL, requiring about 20 strong exhales. That’s only a few breaths more than the XLite but it seems worse, because the valve allows for unrestricted inflation. The reducer on the XLite slows the process, helping to avoid light-headedness.

If you think backpacking is hard enough already, consider the Big Agnes PumpHouse Ultra ($35, 3 oz), which doubles as a stuff sack.

Deflation of the Insulated AXL is fast and easy: open the cap and press the valve flap. I do it while laying on the pad before I get up — the body weight helps to expel most of the air.

Buy now: Big Agnes Insulated AXL Sleeping Pad

Questions about the Insulated AXL, or have an experience to share? Please comment.


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23 Responses to Review: Big Agnes Insulated AXL Pad || Very light & comfy, not very warm

  1. Hunter October 20, 2018 at 10:51 am #

    That’s my experience precisely…

    It really presents a challenge when choosing a sleeping pad quiver, especially when you regularly sleep in cold situations and use a quilt.

    I love my XTherm, but it’s overkill for a lot of trips. I’m a warm sleeper but the insulated AXL really can’t be used with nighttime lows in the high teens or 20s though, whereas an XLite can, all at the same weight.

    Most people don’t want to have to buy 3 pads, or even 2 pads, but you sort of have to with the AXL if you’re ever sleeping below freezing.

    I would be willing to wager that sales of the big Agnes insulated AXL will plummet when the NeoAir Uberlight comes out in the spring. The 3 ounce difference for a semi equivalent warmth is a big deal.

    I love the valve though… As well as the larger side tubes. If TAR could incorporate vertical tube’s with larger side tubes as well as that valve or something similar, it would have an unbeatable product in my opinion.

    • Kango October 20, 2018 at 6:30 pm #

      Well of course the Xtherm is overkill for most trips. That is a 4 season pad. You can pretty much sleep right ontop of snow with it.

    • seanion October 24, 2018 at 3:54 am #

      the 20×72 xtherm is only 15 oz, and it has a valve not requiring a proprietary valve adapter. i dont see how this axl can really compete besides being just a couple oz lighter

  2. Axel J October 20, 2018 at 1:07 pm #

    I have the uninsulated mummy AXL but unfortunately it developed a slow leak so BA had to replace it (great costumer service!). I found the location of the valve ideal for dialing in the comfort range of the pad, simply open the valve cover and press the flap to let air out to the desired comfort firmness while still lying on the pad. I also discovered that the valve flap can easily be temporally dislodged to allow the user to roll up the pad without constantly pressing the flap to allow the air to escape. This greatly speeds up the time it takes to deflate and stow the pad.

  3. Langleybackcountry October 20, 2018 at 1:47 pm #

    Re: Colder temps. Do you think it is insulated enough that the addition of a closed-cell pad (very common for sleeping on snow) would be sufficient for at least mild winter conditions (roughly 15F)?

    Re: Valve. I have the S2S Insulated Ultralight. I loooove the valve design. This is where Therm-a-Rest is losing the battle IMHO. You do not have to hold anything to release the air. I have determined that a good valve is worth an extra oz or to for me.

    Re: Competition The S2S is heavier, and only 2 in thick, but uses a 40d face fabric, so it feels really durable. It has a “balloon” creaking sound and some crinkle that has decreased over time. Better than my XTherm. I it would be quite comfortable if I were a back sleeper, but have found it to be just a little thin and my hip can contact. I mitigate it by using my small ensolite butt pad under my hip. I believe it is also getting a major update for next year.

    • seanion October 24, 2018 at 4:40 am #

      axl has a flush valve, thermarest xtherm has a raised one that makes it far easier to inflate with stuff or plastic bags, easy to deflate too. i cancelled my axl order and am looking at xtherm, for reasons including valve design

  4. Ben October 20, 2018 at 10:22 pm #

    The advantange of blowing ambient air into the pad with the PumpHouse Ultra is two-fold. The air in your lungs is both hot and humid. Blowing hot air into the pad means that it will lose some volume when that air cools down, meaning you will have to add another breath or two before bed to fully inflate it again. And blowing humid air into the pad, well… that humidity will condense as the air cools, and that condensation doesn’t really have any way to escape once it gets inside the pad.

  5. Edward October 21, 2018 at 5:20 pm #

    Still waiting for a manufacturer to sell a short wide (roughly 48” x 25” x 1.5”) pad.

    Haven’t seen one anywhere.

    Yes, there are short pads and wide pads, but no short wide.

    • JP October 22, 2018 at 8:41 am #

      Thermarest used to have a short/wide NeoAir Trekker, but hasn’t offered that in years. Some folks (John Abela @ hikelighter.com e.g.) have posted guides on shortening pads if that helps. My Short/Wide NeoAir Trekker weighs the same as my Regular/Regular NeoAir Trekker FWIW.

  6. seanion October 22, 2018 at 7:37 pm #

    i just bought one but NOW i see that the air valve is flush. YIKES. i never inflate pads with my breath, i don’t want humidity or microbe issues etc cropping up.

    does anyone know if i can effectively use a plastic bag to squeeze air in as i have for my other pads in the past? would i have to rig some kind of adapter?

    • Andrew Skurka October 22, 2018 at 7:47 pm #

      If you don’t want to blow it up manually, get the BA Pump House.

      FWIW, I NEVER inflate mine in any other way than lung-power. I think there is some mold inside my 6 year-old XLite, but it has no effect on its warmth at all.

    • seanion October 22, 2018 at 7:47 pm #

      BTW i do know that there is a $35 / 3 oz option made by big agnes but i don’t feel i should have to use their proprietary solution for something like this.

      • J Ramos October 23, 2018 at 10:42 pm #

        The Exped flat adapter fits these Big Agnes valves (a bit tightly but it does fit and seal). That gives more inflation bag options/brands than just what Big Agnes offers. The Schnozzle will mate with it as does the Sea To Summit bag and their little jetstream accordion thing.

        http://www.backcountryedge.com/backpacking-and-camping-gear/sleeping-pads/exped-flatvalve-adapter.html

        I’m able to store my pads inflated at home after a trip so I still inflate by mouth but it’s important to get that moisture out of there as soon as you can. Extended contact with moisture and/or the presence of mold can deteriorate the coatings on the fabric and cause both delamination and those warranty-claim mystery unfindable unfixable air leaks. I’ve also heard a couple of people share their stories online of Therm-A-Rest X-Lite pads that were punctured many times by small ice crystals inside the pad after rolling them up.

        • seanion October 24, 2018 at 4:33 am #

          appreciate the info. right now i feel like the xtherm might be the best choice. 15 oz for 20×72, has a much more accessible valve design, and insulates FAR better

          • Dan Timmerman November 4, 2018 at 5:30 pm #

            Interesting tidbit about BA pad valves…..a normal soda bottle cap like you’d find on a 2L bottle or whatever fit in perfectly. Cut the top off a bottle, drill a large hole in the cap, screw them together with your bag of choice sandwiched between, punch a hole in that and you have a cheap/easy/available anywhere pump bag.

          • langleybackcountry November 6, 2018 at 11:38 am #

            Seems like filling the bag would be an issue, unless you are sacrificing a bag by putting a hole in it, in which case, why not just get a pump sack? I also can’t see threading the cap on with the bag fabric. Maybe I am missing something?

          • seanion November 6, 2018 at 11:59 am #

            just scoop the bag into the air to fill it in 2 seconds, then put it over the protruding valve and clench fingers around it to get a seal with one hand, and squeeze / push the bag with the other. as the bag gets empty, shut the valve if necessary so you can get another scoop of air without deflating. the longer and narrower the bag, the better. a typical usable one is maybe a single gram, takes up almost no space, and is essentially free

          • seanion November 6, 2018 at 12:09 pm #

            Dan Timmerman yes interesting.. and now i get what langleybackcountry was asking. in that case i’d just use the bottle’s cap and neck to make a protruding valve

  7. Fred October 23, 2018 at 5:31 pm #

    Any comments on the comparison between using it in the hammock vs on the ground? Warmer, colder?

    • Andrew Skurka October 23, 2018 at 9:49 pm #

      It’s too conditions-dependent to say one way or the other. If you find a really soft spot, you can push the AXL pretty low without it being a problem. A hard, thermally conductive site, not so much.

      Similarly, if it’s a calm night, the lad is reasonably warm. If windy, not so much.

      Overall, I’d say that it’s similar.

  8. Karl November 6, 2018 at 7:07 pm #

    Is it just me or has anyone else discovered that these big fat air mattresses are really a pain to inflate after 30 mile days (or 10 mile days for that matter) and that they actually aren’t really that comfortable, either. I did a Sierra pack trip with a really expensive, very thick and highly touted air mattress last summer; I got hypoxia blowing the thing up and my hips started aching about 2.00 am every night for a week. On the next Sierra trip I brought my old Thermarest ‘Prolite 3’ short inflatable pad. It inflated in seconds and my hips never ached. I may be singular here, but that is my experience. I think the air mattress thing is a fad… kind of like foam insulation in sleeping bags (circa 1974). But if it costs an arm and a leg and looks comfy we will buy it. Anyone want an Exped air mattress? You need the VO max of Greg LeMond to inflate the sucker!

    • Andrew Skurka November 7, 2018 at 10:18 am #

      The volume of air required for these pads is not insignificant. The BA pad is 20 breaths, versus 13 for the XLite.

      I don’t think air pads are a fad. But I also don’t think you’ll see a lot of significant improvement in the category either — the AXL and UberLight are against the current limits of material strength. Maybe we’ll see a DCF version within a few years, which might save a few more ounces.

  9. PhilM November 9, 2018 at 4:47 pm #

    If you use a pack liner like a trash compactor bag, you can pretty easily create an inflator that takes one or two light breaths.

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