The following is an edited version of my Big Agnes Horse Thief sleeping bag reviews tested here at BackpackGearTest.org that focuses on the Air Core Mummy sleeping pad. All information below can also be found in the Horse Thief review.

Below you'll find:

Big Agnes Shipping, Packaging, and Delivery Information
Big Agnes Air Core Mummy Weights and Measurements
Initial Impressions and Fit
Field Report
Testing Plan, Contact, and Background Information

1. Big Agnes Shipping, Packaging, and Delivery Information

On Friday afternoon, May 3rd, I received an e-mail from Brad Johnson at Big Agnes. It was a note stating that Big Agnes was eager to read our testing comments, and suggesting that we check out their website, www.bigagnes.com, for the most up-to-date information on the products we were going to be testing. Apparently the catalog lists specifications from pre-production models and there is a slight difference from the final products. I thought this was a pretty nice personal touch from a company that appears to work pretty hard to offer a small-shop image.

Not an hour later, I received a plain brown cardboard box package from UPS. In it was the following:

Big Agnes Horse Thief Sleeping Bag - size long, with stuff sack
Big Agnes Horse Thief logo cotton sleeping bag storage sack
Big Agnes Air Core Mummy Sleeping Pad - size long, with stuff sack and repair kit
Big Agnes Girdle compression harness
Packaging Slip / Receipt
Big Agnes 2002 Catalog

Attached to the Air Core Mummy Sleeping Pad was a full-color product information tag outlining features of the various Air Core pads.

Attached to the Horse Thief Sleeping Bag was a full-color product information tag outlining the features of the Divide Series of Big Agnes bags, a tag with instructions on how to insert the sleeping pad into the bag, a Big Agnes sticker, and a Big Agnes coupon for either $10 off a sleeping pad, a Big Agnes logo hat, or a Big Agnes logo t-shirt.

2. Big Agnes Air Core Mummy Weights and Measurements

I weighed and measured the products:

Big Agnes Air Core Mummy Sleeping Pad - size long: 1 pound 7 ounces (1 ounce over specification)
Big Agnes Air Core Pad stuff sack: 1 ounce
Big Agnes Air Core Pad repair kit: .5 ounce

It's refreshing to see a manufacturer list honest weights (listed weights were about 96% accurate, easily within normal fabric variance margins)

The Air Core Mummy measured as stated - 78" x 20"

3. Initial Impressions and Fit

The Air Core Mummy pad is basically a beefed up, mummy shaped, high-quality air mattress similar to the good old swimming pool inflatables. The first time it's blown up takes a little longer because the interior is stuck together after manufacturing and shipping. Big Agnes claims about a 2 minute inflation time. The first time took about 3 minutes, the second time just over 2. This is at a casual inflation rate that doesn't leave you dizzy. I imagine blowing this up at 12,000 feet could be a bit of a challenge. The pad is about 2.5" thick, easily the thickest and most comfortable pad I've been on. I'm an incurable side-sleeper that finds even Therma-rests miserable, so this pad should be an interesting test. Initial side-lying is encouraging - lots of cushion and no numb arms.

Inserting the pad into the sleeping bag is very simple and straightforward. I'm surprised by the amount of instructions Big Agnes provides on this - it's really quite simple. The mummy pad fits perfectly, but leaves enough room that you could probably squeeze a cut-to-fit foam pad in the sleeve as well. This is something I will likely have to do, as the pad has no insulation, is rated to 32*F and I plan to sleep on snow at least a few times during testing. Once the pad is sealed inside its sleeve, the bag is much like any other - double-slide zipper that can vent down around the knees and zips up to the top. No slipping off this pad, that's for sure.

After doing all the weighing, measuring, inflating, and measuring, it was time to climb into the bag. I have a 52" chest and wear an XXL in almost everything. I have plenty of room in my 68" girth 20*F down sleeping bag, so I figured I'd have room to toss and turn in the 70" girth Horse Thief. This is not the case. The girth of the Horse Thief is indeed about 70" - BEFORE you insert a 2.5" thick sleeping pad. This takes up a lot of space. Imagine taking your traditional sleeping bag, then putting your sleeping pad on the inside. It changes the fit significantly.

Field Report:As I mentioned in my initial report, the girth of the Horse Thief is indeed about 70" - BEFORE you insert a 2.5" thick sleeping pad. This takes up a lot of space. Imagine taking your traditional sleeping bag, then putting your sleeping pad on the inside. It changes the fit significantly. This characteristic has not changed, and has actually become a bit of an annoyance. I now prefer to sleep on top of the sleeping pad and not take advantage of the pad sleeve that makes the Big Agnes System unique. I don't slide off of the pad and now I'm not so restricted by the one-piece system. If you're a side sleeper who curls up in the fetal position often, the Big Agnes System makes this difficult. You will have better luck simply sleeping on top of the pad.

The Air Core Mummy pad is easily the thickest and most comfortable pad I've ever slept on. As a hardcore side sleeper, I can't say enough good things about this pad. It packs up to nothing, it's amazingly cushy, very light for its thickness and I've not been cold on it yet (the Air Core has no foam inside, and therefore little theoretical insulation value). It does take a bit of experimenting to find the right inflation level, but once you do, it's like sleeping on air. To truly test the comfort, I experimented at home a few nights, switching mid sleep between my Sealy bed mattress and my Air Core. I slept as good on the Air Core as I did in bed. At this point, if the cold becomes a problem, I'll carry a thin foam pad to put under the Air Core. I've never carried two pads in my life, but the comfort I get from the Air Core is worth it. I'd still come in well under 2 pounds, and I know I'll be able to go hard the next day after a good night's sleep. I have a finicky lower back, so good sleep is important. The Air Core is simply the best backpacking mattress I've ever slept on.

So far, I'm really impressed by the Big Agnes products. I really like the Horsethief Bag and the Air Core Mattress, although I'm not so sure about the two products combined - the Big Agnes "System". I'm finding the bag inside the sleeve too restricting and too drafty. I've had much better luck just laying on top of the pad. The bag has sufficient coverage to wrap around me without gaps. If I eventually find this is the way I'll always use it, I could cut off one layer of fabric on the bottom (eliminating the sleeve and leaving just a bottom layer of nylon). This would save a couple of ounces.

Testing Plan: I will be testing the Air Core Mummy over the coming months primarily in the North Cascades. I went skiing yesterday (May 4th), and it's snowing today, so we've had quite a winter in the Northwest. This will give me an opportunity to test on snow and in low-elevation areas until the high country opens up in August and September. I'll primarily be using this setup in a tent, but may try it out under a tarp. I will definitely try to push the limits of the temperature rating of both the bag and pad.

Contact and Background:

Product Information, www.bigagnes.com

Review by Curt Peterson, e-curt@attbi.com

Background Information

I live in Seattle and do the vast majority of my outdoor activities in Washington State. During the summer I head to the backcountry at least every other week, averaging 5 or 6 multi-day trips in July and August. In the fall and early winter, I usually do a couple dayhikes a month and probably one overnight per month. In the winter, I ski 1 to 2 days per week, and backpack in the Central Washington steppe 1 to 2 times over the season. Spring and early summer I usually climb, most often on the Cascade volcanoes. I usually go to the coast in Olympic National Park at least once a year, and summit at least one big volcano a year, so the range of locations that I test gear is pretty broad. I also do a 3 mile walk each day with my dog, no matter what the conditions are, and I often evaluate gear during that time.

I wear an XXL in most outdoor clothing. Tall sizes if they are available - which they rarely are. I'm 6'3", about 270 pounds. I played football in college, so I've been pretty active my entire life. Finding quality gear for really big folks can be quite a challenge - most manufacturers don't really make products for large people. Clothing and sleeping bags tend to be the big challenges.

I have been camping and backpacking my entire life. First in Utah as a child, in Minnesota until I finished college, and here in Washington ever since. I served on the Product Test Committee for Seattle's biggest outdoor gear retailer for a two-year term in the mid-90s, then guided backpacking tours with my wife in Olympic National Park for a few summers. I've been interested in the most recent shift to lightweight thinking for the past couple of years and really enjoy checking out new ideas and approaches to backpacking.

Read more reviews of Big Agnes gear
Read more gear reviews by Curt Peterson

Big Agnes Air Core Mummy Sleeping Pad

All material on this site is the exclusive property of BackpackGearTest.org.
BackpackGearTest software copyright David Anderson