Field Report: Big Agnes REM Insulated Air Core Pad--Rick
- Big Agnes Insulated Air Core Inflatable Sleeping Pad
Name: Big Agnes Insulated Air Core Inflatable Sleeping Pad
Model: 20x72x2.5 mummy pad
Maker: Big Agnes Inc.
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);
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: 20 oz (567 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: Rick Dreher
Height: 6 ft (1.83 meters)
Weight: 175 lb (79 kg, 12.5 stones)
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 date: August 1, 2004
"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 optionin 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 mattresswhere'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
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 fluffedsuch
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.
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.
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
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 already 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 (rectangular ones are
also available) can be described as coffin-shaped, with the head and
lower leg areas lopped off at angles to reduce size and weight. The
plastic inflation valve is at the head end, to the sleeper's right.
It's placed conveniently to allow air to be released to adjust
comfort without getting out of bed. The label side is the sleeping
sidewhere 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 1.4 oz (40 g) lighter than the Big
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
Visual inspection holding the inflated pad up to the sun reveals a
problem: three of the batting strips have come loose several inches
at the pad's head end, and now flop around inside their respective
inflated tubes. I have no way of knowing whether this is a
production problem or one that's developed with use. I've learned to
shake the mattress, head end down, to coax them back in place before
setting it on the ground 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 any warmth in those areas.
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 [-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 turnan experiment I'm unlikely to orchestrateit'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 than. 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
My thanks to Big Agnes and BackpackGearTest for the opportunity to
participate in the insulated Air Core Mummy Pad field test.