Big Agnes Insulated Air Core Inflatable Sleeping Pad
Field Report

Product Information

Name: Big Agnes Insulated Air Core Inflatable Sleeping Pad
Model: 20x72x2.5 mummy pad
Maker: Big Agnes Inc.
http://www.bigagnes.com
Year of manufacture: 2004
Product Type: Insulated three-season backpacking air mattress
Options: None available
Ships with: Stuffsack; repair kit (patches, glue, valve and o-ring); hangtags; brochure
Size tested: 20x72x2.5
Measured dimensions (inflated): 19.5 x 71.5 x 2.5 inches (49.5 x 181.5 x 6.5 cm)
Measured dimensions (deflated, folded and rolled for storage): 9.5 x 4 inches (24 x 10 cm)
Specified weight (updated): 21 oz (595 g)
Measured weight: 18.6 oz (527 g)
Weight of stuffsack and repair kit: 1.0 oz (28 g)
Claimed low-temperature range: 15 deg. F (-9 deg. C)

Tester Information

Tester: Rick Dreher
Email: redbike64(at)hotmail(dot)com
Male
Height: 6 ft (1.83 meters)
Weight: 175 lb (79 kg, 12.5 stones)
Age: 50
Location: Northern California, USA
Years backpacking experience: 37
Backpacking skill level: Mid to advanced
Backpacking style: Lightweight, mostly alpine (see bio at end of report)

Report date: August 8, 2004

Introduction

“To sleep, perchance to dream; ay, there’s the rub.”

Hamlet certainly had his reasons to not sleep well but dang it, when I’ve hiked my rear off for a long day on the trail I think I’ve earned the right to a good, long night’s sleep. Instead, I frequently find myself waking several times during the night, often because of the hard, cold ground. To the backcountry we go with our pads and mattresses, promising ourselves that THIS TIME we’re going to sleep the sleep of the angels.

Sometimes we do, sometimes not.

Our tired bods need respite from that stony ground. Our weapons include simple foam pads, clever self-inflating pads of foam encased in airtight fabric, and the good old air mattress. I love air mattresses for their comfort but discovered early in my camping and hiking career that unless they’re paired with a foam pad they’re strictly a warm-weather option—in merely cool weather they can freeze me solid. The air contained in the mattress’s thick tubes conspires to rapidly suck away body heat on swirling convection currents and because the sleeping bag is flattened underneath me, it’s helpless to stop this evil heat drain.

Big Agnes had an idea: slap some manmade fiber insulation against the inside top of each tube and stop the heat vampires from their cruel deeds. Well, does it work?

General Product Description

Is it possible that this little black nylon stuffsack holds a full-length air mattress? Yup, it does. The Big Agnes REM Air Core Mummy Pad (BA Air Core) is fashioned of black 70D rip-stop nylon and folds small, small, small. Unfolding it there’s little hint that this isn’t a plain air mattress—where’s the insulation? Folding the fabric over in different spots and rubbing it together tells the tale: there’s a relatively thin layer of pile adhering to one side of the mattress on the inside, perhaps a quarter inch (6 mm) of the stuff.

The “stuff” is Primaloft Sport, a synthetic insulation I’ve run into once before as the fill in the Integral Designs Mummer liner bag I tested for BGT. For decades, folks have been blowing loose down into air mattresses and inflating them with air pumps to achieve an insulated mattress while keeping the down dry and fluffed—such mattresses are available commercially today. Big Agnes has taken a different approach by placing a layer of synthetic fiberfill on the air mattress’s sleeping side. The advantages of the synthetic approach over loose down are, in theory, that moisture from your breath won’t rob the insulation of its ability to keep you warm (eliminating the need for an air pump) and the insulation shouldn’t shift and redistribute itself, leaving cold spots. My soak-and-wring-dry experience with Primaloft Sport supports the notion that it can shed water; a few days in the hills should tell whether condensation from my breath inside the mattress has affected the pad’s warmth.

Summary

Success? Mostly.

My first few nights with the BA Air Core showed mostly strengths and a few weaknesses. The pad is comfortable, sooo comfortable: back sleeping, side sleeping, stomach sleeping are all significantly more comfy than on any backpacking foam pad or self-inflating pad I’ve used. When it comes to protecting us from the ground, thickness rules the day and the BA Air Core’s 2.5 in. (6.5 cm) of float trumps the competition. Warmth, however, has been a mixed bag--I’ve slept warmly on some nights and shivered on others.

The Details

I’ve taken the BA Air Core into California’s Sierra Nevada in late spring and early summer for this test. All trips have been in fair weather, with clear skies and nighttime temperatures ranging from the high 30s to the mid-50s (3 to 14 C). Camp elevations have been between 8,000 and 9,500 ft (2,400 to 2,900 m). I’ve slept in a one-man single wall tent, under a tarp and in a bug bivy. My sleeping bags have been a Mont-Bell Alpine Down Hugger #5 and a Western Mountaineering Ultralight.

As with any air mattress, the key to maximum comfort on the BA Air Core is correct inflation, which involves some tweaking. Inflating the pad takes me about a dozen breaths (take your time at altitude unless you relish becoming staggeringly dizzy). I like to do this right after getting into camp to allow the insulation time to decompress. As evening arrives and the ambient air temp drops, the mattress droops some so I must add more air. Ideally, I’ve added enough air that once I go to bed, all I have to do is release air stepwise until the pad is “just right.” The valve opens and closes smoothly to aid this process but, If I let too much out, it’s then a wrestling match to get the pad out from under me, add air then get it back underneath. If I’m in the bivy I have to actually evacuate to perform this feat.

I use a clothes-filled cloth sack as a pillow, placing it between pad and sleeping bag hood. The sack can sometimes squirt out of place due to the slippery nylon used for both the pad and sleeping bag. The pillow will stay put underneath the pad but isn’t as comfortable there. The pad’s narrow foot end makes it fairly easy to slide my legs off, onto the ground. Fortunately I’ve not found myself doing this often enough that I’d prefer a larger, heavier rectangular pad. Finally, the Air Core will slide on a silnylon tent floor and it’s important to pick a level tent site to keep this from becoming a problem.

A sleeping system, pad/mattress included, is either warm enough or not. Especially for folks who’ve been shaving pack weight over time, we usually come to some point where we’ve gone too far and find ourselves shivering through an endless sleepless night. I may have hit this point the very first night I use the Air Core. In a relatively tiny backpack (2,400 ci/39 L) along with the pad I had the Mont-Bell sleeping bag and a bug bivy as my sleep system. The weather was nice enough that we chose not to pitch our tarp but even though the night was still, it got so cold that I put on pretty much all my clothing during the night and still slept little. The morning temp was under 40 F (3 C). Standard disclaimers about my metabolism on that day apply: it’s possible that somebody else using the same equipment in the same conditions would have been fine, but I was not. What I also cannot say is how much of my chilled state was from the sleeping bag (which, like the pad is rated for these temps) and how much was contributed by the pad. I did seem to be colder underneath than on top.

Other nights in other campsites I’ve used my WM bag which is considerably thicker than the Mont-Bell, and slept in a Tarptent or under a flat tarp. Temps stayed in the 40s and 50s (7 to 14 C) and I slept warm and well. I’ve not given up on the BA-MB combination because their combined bulk and weight are impressively small. But I suspect I have to limit their use to mid-season trips unless I perhaps combine the pair with a really warm garment, such as a fat down vest or jacket.

Design, Materials and Construction

As noted, the BA Air Core is an air mattress fashioned from coated, somewhat slippery rip-stop nylon fabric. The mattress has eight tubes running lengthwise; the between-tube seams have inner fabric baffles, i.e., they aren’t welded through directly to the other side. This test mummy-shaped Air Core might be described as coffin-shaped. If you were to start with a rectangle and lop off the head and lower leg ends at angles, you’d have the mummy pad’s basic shape. This lopping saves bulk and weight over a rectangular pad (also available). Of course it reduces sleeping room too. As I lay on my back, the plastic air valve is at the head end, to my right. This placement makes it convenient to release air for comfort without getting out of bed. The label side is the sleeping side—where the insulation is.

On first unrolling it’s difficult to find tactile evidence of any insulation in the Air Core, but after several minutes inflated, a pinch test of both mattress sides reveals the insulation’s presence on top. I initially didn’t think It would be possible to figure out what’s going on inside without dissection, but then discovered that by holding the Air Core to the sun I can see strips of Primaloft batting in each tube. They appear to be held in place by the baffle-to top surface seam on one side only. I’ll guess that each batting strip is about a quarter-inch (6 mm) thick.

The test pad is a surprising 2.4 oz (68 g) lighter than the Big Agnes specification (updated by BA since I received the test mattress).

A note on the Big Agnes bag and pad system: This and other BA mummy shaped pads will fit inside BA sleeping bags. To save weight, bulk and cost, BA bags dispense with insulation underneath, instead providing a fabric pad sleeve. In that role the test Air Core pad should fit inside a BA sleeping bag like a glove, but I regret to say I don’t have a BA bag with which to test the system. That Horse Thief bag sure looks interesting, too.

Wear and Tear

The BA Air Core’s coated rip-stop exterior shows some minor scrapes. Dirt clings to the black fabric but wipes off easily. Inflation tests at home show the mattress slowly loses air overnight, implying a very slow leak, but dunk tests don’t reveal where. Without evidence of a fabric pinhole or failing seam I have to suspect the valve.

Visual inspection holding the inflated pad up to the sun reveals a problem: three of the batting strips have come loose for several inches at the pad’s head end; they now flop freely inside their respective inflated tubes. I don’t know whether this is a production problem or one that’s developed with use. I’ve learned to shake the inflated mattress, head end down, to coax them back in place before using the pad in hopes that they’ll stay put during the night. I can’t tell whether they cling to the tube tops or not; if not, they won’t provide warmth in those areas. Fortunately the affected area is a small proportion of the whole mattress.

Conclusions

The Big Agnes Insulated Air Core mattress fulfills most of its considerable promise of making backcountry sleep a very pleasurable experience. The comfort is undeniable, but I remain skeptical that it’s truly warm down to the temperatures Bag Agnes claims for it (to 15 deg F [-9 C]). My early test with a very light bag on a night much warmer than that leaves my original doubts in place.

Compared to my Therm-a-Rest backpacking pads and plain foam pads, the BA Air Core is much more comfortable while taking up less pack space. It’s lighter than the T-Rests, heavier than the foam pads. Without experiencing a single chilly night dedicated to trying each in turn—an experiment I’m unlikely to orchestrate—it’s not possible to reliably rank them for warmth. The crux of the temperature question is whether using the Air Core necessitates taking a heavier, bulkier sleeping bag than I would have otherwise, negating the pads obvious weight and bulk advantages over the options.

Despite my remaining reservations about warmth, considering its demonstrated comfort, ease of use, relative light weight and very compact packed form, the BA Air Core should get serious consideration for space in your gear closet and on the trail.

Long-Term Test Questions

* Will the BA Air Core mattress be reliably warm for me into the fall season? Could a small, thin torso-length foam pad (such as those used in some backpacks) extend its cold-weather range?

* Will the mattress continue to resist punctures, cuts and abrasion, and will the overnight air loss get any worse?

* Will the remaining insulation stay in place or will it continue to pull away from the seams?

Brief Backpacking Bio and Cold, Hard Ground Experience

When I first joined the Boy Scouts they neglected to tell me that some kind of mattress would be nice underneath my kapok sleeping bag. A couple of trips sleeping on the ground wearing every stitch of clothing--and my boots--convinced me to look around and see what the comfortable kids were sleeping on. A-ha, air mattresses!

So I got one. And still I froze, but the hard ground was far, far away, a definite improvement. I later learned the newspaper insulation trick and was a happy sleeper the rest of my Scouting career (in kapok), as long as we weren’t backpacking.

Backpacking first had me carrying an air mattress, then a mattress and ensolite foam pad, then just the pad (with some stops along the way for testing bubble wrap, space blankets and the like). The wooded Cascades and Olympics usually provided sleeping spots soft enough that an insulating pad was fine, plus I was a lot more…pliable then. The Therm-a-Rest came along after I’d switched to California’s Sierra Nevada where the elevations are manly and the rocks are too, and rocks are what I normally sleep on. Never mind the weight and bulk, the T-rest had me sleeping again. But never like those early days in the Northwest.

I learned camping and hiking in Boy Scouts, tramping the Washington Cascade foothills (lugging canvas pup tents, Trapper Nelson and BSA aluminum-canvas backpacks, kapok sleeping bags and always an axe). From these beginnings I eventually learned backpacking as a singular pursuit and found a home away from home in the Cascades and Olympics. Now living in northern California, most of my hiking is in the Sierra Nevada with trips ranging from overnight to weeklong excursions. I occasionally hike in the coastal ranges as well. I’ve been fairly successful shedding pounds and ounces from my pack the last three or four years. I’ve been doing this for several reasons: traveling easier and farther, freeing myself from as many trappings as I’m comfortable discarding, and extending the duration of my backpacking career. My total pack weight for three-day summer excursions, including food and water, is now roughly 25 pounds (12.5 kg), and a recent eight-day trip starting weight was a bit over 30 (14 kg).

My thanks to Big Agnes and BackpackGearTest for the opportunity to participate in the insulated Air Core Mummy Pad field test.

RTD 8.8.2004