Big Agnes Zirkel sleeping bag and REM Air Core mummy pad report
- Big Agnes Zirkel sleeping bag and REM Air Core mummy pad
Web site: http://www.bigagnes.com/
Tester: Mara Factor
Test Locales: Medford, MA (north of Boston); Long Trail, VT; Trail Days in
Damascus, VA; and a couple of spots along the Appalachian Trail in NY and
Date: July 30, 2002
Background: I have been hiking and backpacking extensively since 1989.
Weekends frequently find me in the White Mountains of New Hampshire. Longer
trips I've taken include (but are not limited to) such diverse locations as
Copper Canyon, Mexico; Annapurnas, Nepal; Olympic Mountains, Washington;
Austrian Alps; Paria Canyon, UT and AZ; and a 1999 thruhike of the
Item(s): Big Agnes Zirkel sleeping bag and REM Air Core mummy pad - long
Acquired: May 2002 as an adjunct test to the ongoing Horse Thief test
Reputation: I became familiar with Big Agnes as a result of my participation
on the BackpackGearTest list. Big Agnes is one of the few sleeping bag and
pad manufacturers taking a lead with the concept of lightening bags by
eliminating the mostly useless insulation that traditionally gets compressed
under the hiker while sleeping.
Description: The Big Agnes sleep system comprises an integrated sleeping bag
and pad. The mummy shaped top bag has a sleeve on the bottom to accommodate
the mummy shaped pads offered by Big Agnes.
The Zirkel sleeping bag is a 20 degree bag. It has 775 fill down and a water
resistant, breathable Pertex shell. It is cut generously wide, has a draft
tube both at the zipper and at the bag/pad integration points, draft collar,
and a hood with built-in pillow case, drawstring and Velro closure.
I ordered the large to accommodate my height.
Two features I have not tested include the ability to mate right and left
zipped bags and the use of an additional fully integrated overbag rated to
40 degrees on its own.
The REM Air Core Mummy pad is a true air mattress with only enough internal
structure to keep the air in six long baffled columns. Unlike self-inflating
open cell foam pads, this pad requires you to blow up the pad. True to the
documentation, it is easily inflated in about two minutes. Firmness is
determined by how much air you blow in. Because there is no internal foam,
the pad packs suprisingly small. It is shaped to exactly fit into the mummy
shaped sleeve on the bottom of the Zirkel bag. Because it is essentially one
large air chamber, it only provides limited insulation from the ground.
Both the bag and pad came with heavy coated nylon stuff sacks. The stuff
sack for the pad includes a repair kit. The sleeping bag also comes with a
large cotton storage sack.
Cotton storage sack: 11.5 x 30", 4 oz.
Bag stuff sack: 8 x 15", 2 oz.
Bag: 2 lbs 8 oz., weight from web site: 2 lbs. 5 oz.
Pad stuff sack with repair kit: 5 x 11", 2 oz.
Pad: 1 lb 6.5 oz., from web site, 1 lb 6 oz.
Pad: 2.5" x 20" x 78" once inflated
Loft: 2.75 to 3.25" as measured with the highly scientific (NOT!) yardstick
and ruler method. This measurement was taken after a few weeks worth of use
and related stuffing and unstuffing. While at home, the bag has always been
stored in the storage sack.
Fit: While many lightweight backpackers tend to go with short sleeping pads
to save weight, given the integrated nature of the bag and the pad, it is
necessary that the matching pad and bag be used to optimize performance.
The 78" long bag and pad are generously cut for my frame and could easily
accommodate taller and/or larger people.
Comfort: As a large, side sleeping, woman, I've always needed the extra
thickness and padding of a full length Thermarest LE. With the REM air core
pad, I can easily get the necessary comfort to get a full night's sleep
while saving myself nearly a pound of weight.
Previously, I had also always used a synthetic fill bag. My first impression
of the 775 fill down was that of warmth and comfort. The down bag is much
softer and warmer than my ancient 20 degree Lite-lost (err, loft) bag I had
been using for years. My impression of the comfort of the down has not
changed during my field use of the bag.
Design observations: I have problems zipping the pad beyond the shoulder
area. This difficulty appears at the point where the zipper curves upward to
meet the hood. Even outside the bag, I have sometimes have difficulty
zipping the bag past this point. With extra effort, it zips properly, but on
cold nights, or with cold fingers encased in gloves or mittens, this may
prove frustrating. Because I only have this difficulty when the bag is
integrated with the pad, I am reasonably confident this has nothing to do
with the zipper and is just a stress point in the design.
When using a conventional bag and pad, if you want to sit up, the pad stays
on the ground and the bag stays with you and keeps you cozy. With the Zirkel
the pad either comes up with you and pulls back against you or you have to
unzip the bag and sit up without the bag.
Similarly, I like to stretch my back by pulling my knees to my chest. With
the incorporated pad, I can no longer do this. The Zirkel is roomy enough
that some people with short legs may still be able to do this back stretch.
With my long legs (38" inseam), the pad would have to bend with my legs and
that just does not work.
As a side sleeper, I'm used to taking the bag with me as I turn from side to
side. Among other things, this always ensures that the opening stays in
front of my mouth and nose. With the Big Agnes, the bag stays in place and I
turn inside the bag. Not unexpectedly, this may be a problem on colder
nights. When discussing this, I always joke about my not yet figuring out
how I can breathe through my ear. Sure enough, if it's cold and I close the
hood, there's no way for my mouth and nose to stay at the opening. For
temperatures around freezing, so far I've been able to get away with wearing
a thick hat or balaclava so that I do not have to tightly close the hood.
Time will tell if this will work down to the full range of the Zirkel bag.
The built-in pillow case left me skeptical at first. Initially, I put my
fleece jacket in it. I pulled the fleece jacket out almost immediately as I
preferred the soft fleece against my face and did not like the fact that the
pillow was "tied down".
Later, in the interest of lightening my load and making it smaller, I
switched to a synthetic filled jacket instead of fleece. Unlike with fleece,
the slippery nature of the shell material is not conducive to folding the
jacket into a nice pillow that stays properly folded. In this case, the
built-in pillow case allows me to stuff the jacket in the sleeve and
prevents it from sliding out of the sleeping bag while I sleep.
Unfortunately, I find that while the jacket fills the pillow sleeve nicely,
once stuffed, the hood no longer fits around both my face and pillow. While
this is not an issue in warmer temperatures, in marginal temperatures, this
may prevent me from using the jacket as a pillow in order to use the hood as
effectively as possible.
For lightweight packing, I found the pad adequate for providing a barrier
along the back of my lightweight backpack. Even though it does not provide
as much support or padding as a stiff closed cell foam pad or even a
self-inflating open cell foam pad (full-length Thermarest LE), it is
adequate for smoothing out any pressure points other gear items might have
formed as they got packed in my backpack.
Temperature observations: While the Zirkel is rated to 20 degrees, the REM
Air Core pad is only rated to 32 degrees. Brad, at Big Agnes, made sure I
was aware of this "mismatch" and suggested I consider one of the Big Agnes
self-inflating pads with temperature ratings well below freezing. I declined
knowing that would have eliminated the weight savings I was seeking. My
intention, knowing many closed cell pads weigh less than a pound, is to try
using a thin closed cell pad in conjunction with the REM Air Core pad to
extend the temperature range of the pad to match the bag rating and still
weigh less than my Thermarest.
At Trail Days, I was camping in my Nomad tent. We had everything from warm
days in the 70s to wet rainy nights, to nights where the temperatures dipped
below freezing, even at ground level, as evidenced by the frost on the grass
early in the morning.
On the coldest night at Trail Days, I crawled into my bag wearing just a
light shirt and underwear. While my legs were still comfortable, my hips and
butt, where they pressed against the bag as I lay on my side, got cold very
quickly. I pulled on some light fleece lined Lycra bike tights and was warm
for the rest of the night. The tights were not necessary on the warmer
Each morning, I woke up to a tent coated with condensation. Given the
thickness of the pad and the length of the sleeping bag, both the head and
foot portion of the bag came into contact with the wet tent walls. The
Pertex fabric did a great job of repelling the water. This test alleviated
most of my concerns about using a down sleeping bag in environments along
the east coast that are typically wet and humid.
Camping under the stars at the RPH shelter in New York on a cold night on my
way home from Trail Days, I assumed I would wake up to some condensation on
the exterior of the bag itself. That ended up not being the case. I did wake
up cold early in the morning and could tell I was cold from the lack of
insulation beneath me. I pulled my old rectangular closed cell foam pad out
and put it inside the Zirkel so that I was sleeping on top of that and the
REM Air Core pad. It made the bag a little more tight fitting, but
immediately solved the insulation problem.
I anticipate doing a bit of testing to find a thinner closed cell foam pad
that I can cut to shape and put in the sleeve with the REM Air Core pad to
extend the Zirkel system to 20 degrees or so.
On the Long Trail, I experienced everything from warm, dry nights to cold,
wet nights and did a bit of experimenting. I used the system in the
conventional sense with the pad inserted into the sleeve on a warm night and
found myself either too hot or too cold � and sometimes at the same time. I
ended up pulling on light tights so that I could keep body parts exposed
without getting bitten by mosquitoes or black flies.
On another warm night, I did not put the pad in the sleeve and was free to
use the bag more as an unzipped quilt and ended up with the "bottom,"
uninsulated, layers on top of me. As the night got cooler, I shifted the bag
so the down was on top of me. This works well to prevent overheating in the
20 degree bag on a warm night.
On one marginal night, I left the pad out of the sleeve and ended up having
a night with some cold blasts as I shifted and opened up some gaps between
the down bag and the pad. I recommend using the integrated pad and bag as
designed on marginal nights.
On the cooler nights, using the bag and pad as intended, the bag stayed
One night, I woke up to a violent wind driven rain blowing directly into the
shelter. As I was alone in the shelter and the shell of the bag was getting
wet, I moved to the back of the shelter and went back to sleep. The bag was
dry by the time I got up in the morning.
The little slit on the pocket for the pad near the head so you can add or
remove air from the pad without having to take the pad out of its sleeve. It
may be a small feature but I really like it.
The Pertex shell is soft to the touch and appears to breathe well and
effectively repel tent wall condensation and spray from wind-blown rain.
The pad is plenty cushy, even for heavier bony side sleepers.
I miss not being able to sit up while still in the bag.
There is no way to effectively keep the hood tight around your face while
you are sleeping on your side. This forces you to either breathe into the
bag (not recommended as it introduces moisture into the down) or loosen the
hood and make do - possibly with a balaclava.
While I don't believe this should be a major concern for anyone, the long
length of the (large) system may not fit well in some of the smaller, older
shelters along the AT where the sleeping shelf in the shelter may only by 6'
Summary: The REM Air Core pad has become my pad of choice for hiking in
temperatures above freezing. Coming from an already fairly luxurious
full-length Thermarest LE, I find I sleep equally well on the REM Air Core
pad. The weight savings (15 oz.) over the Thermarest makes the pad an
attractive option for those hiking in warm weather.
[I am providing the following information as a service to those that would
otherwise be curious. According to their web site, Big Agnes does not
recommend the REM Air Core pads for use in temperatures below freezing.]
I believe with a thin closed cell foam pad, cut to size, the REM Air Core
pad may prove to be a lighter option than my full-length Thermarest LE for
cool spring and fall hiking with limited nights in the 20 to 32 degree
I do NOT recommend the REM Air Core Pad for winter hiking in very low
temperatures. I have serious concerns about ice buildup in the pad due to
the introduction of warm moist air into the pad each time it is inflated. I
do expect moisture to accumulate in the pad over time and use of a pad with
such a buildup in such cold temperatures could result in damaging ice
forming inside the pad. Additionally, ice buildup could prevent the pad from
inflating properly should moisture build up and then freeze after deflation.
Recommendations for Big Agnes' consideration:
Use Pertex or sylnylon stuff sacks. Both would be lightweight, water
Head and toe pad pockets and a hip strap may be enough to hold the pad in
place and save the weight of the full-sized sheet of fabric.
Questions for other REM Air Core pad users:
Are there any "tricks" to deflate the pad? I find I have to press air out
from the bottom of the pad, and fold sections up until I reach the head
area. The I unfold and fold lengthwise once, and then widthwise twice to
make a "pad" the appropriate size for back protection in my backpack.
Also, according to the Big Agnes web site, you can leave the pad in the bag
sleeve and put both into the sleeping bag stuff sack. While the sleeping bag
stuff sack seems to have plenty of room for both the bag and the fully
deflated pad, I have not been able to get enough air out of the pad while it
is still in the sleeve to make this work. Are there any tricks for this
While I probably will not be stuffing the pad with the bag, I am curious how
that works and would like to successfully try it at least once.
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- Nice report Mara--as usual. I'm in the market for a new lighter weight bag
and have been leaning toward a Big Agnes. Your report has given me some
additional things to think about--especially the problems you noted with the
----- Original Message -----
From: "Mara Factor" <m_factor@...>
Sent: Wednesday, July 31, 2002 2:38 PM
Subject: [BackpackGearTest] Big Agnes Zirkel sleeping bag and REM Air Core
mummy pad report
> Big Agnes Zirkel sleeping bag and REM Air Core mummy pad
> Web site: http://www.bigagnes.com/
> Tester: Mara Factor