Field test by Mara Factor

Big Agnes Zirkel sleeping bag and REM Air Core mummy pad

Web site: http://www.bigagnes.com/

Tester: Mara Factor
Gender: Female
Height: 6’1"
Weight: 195
Inseam: 38"
Age: 36
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 PA.
Date: July 30, 2002
Email: m_factor@hotmail.com

Web: http://friends.backcountry.net/m_factor

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 Appalachian Trail.

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.

Specifications:
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.

Field use:

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 nights.

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 uniformly warmer.

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.

Pluses:

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.

Minuses:

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' deep.

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 range.

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 resistant options.
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 "problem?"

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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Reviews > Sleep Gear > Sleeping Bags > Big Agnes Zirkel 20 degree bag > Field test by Mara Factor

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