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Sleeping Bag Review – No 215 – September 2002

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Feathery cocoonsZipping into the finest lightweight down sleeping bags

A few years back, my friend Pete and I topped out on Andromeda Strain, a huge mixed alpine route in the Canadian Rockies. We were cold, tired, and unsure about how to get off the mountain. After wandering around by headlamp in the inky night for a few minutes, it soon became obvious that our safest option was to wait until dawn before heading down. No big deal, except that we had left our bivy gear at camp, hoping to sprint the route in a day.

We crawled into our packs, sat down on the ropes, and resigned ourselves to the fact that for the next 10 hours we were going to be absolutely freezing. Carrying bags would have slowed us down a bit, but with two feet of fresh snow on the route, we should have expected to be benighted. Immediately after that endless night of shivering five years ago,

I ponied up for a two-pound down bag, and have since been toasty warm on even the crummiest of forced bivies. Since coughing up the cash for my purchase, however, advancements in lighter shell material, smaller zippers, and loftier fill have vastly improved the warmth-to-weight ratio of the current crop of lightweight down bags, mandating that I start shopping for an upgrade.

First, I trimmed the crowded field down to encompass only the bags that met my climbing-specific needs. I wanted a down bag with a 15- to 20-degree Fahrenheit temperature range, weighing 2 pounds, 5 ounces or less, and offering a full- or three-quarter-length zipper.

This review excludes bags with synthetic insulation because down is warmer and more compressible for its weight than man-made fibers — crucial considerations for any alpinist. Down is also incredibly durable. Synthetic bags start to show degradation after just a few seasons of heavy use. Treat a down bag well, though, and it will last you 15 years. Plus, feather bags have a natural comfort range thanks to hairs on the down clusters that react to the outside temperature. When it’s cold, the hairs stiffen and loft increases. In warmer temps, the hairs relax. And let’s not forget about comfort! Nothing feels better than zipping yourself into a heap of feathers after a long day out. The only drawback to down is that it’s useless when wet (Synthetic fill retains some insulative value when wet, making it suitable for soggy environments). However, with today’s new shell materials you’d be hard pressed to thoroughly soak your bag unless something drastic happened — like an open bivy in the rain.

All of the bags tested use an advanced polyester or nylon shell that has been coated with a durable-water-repellent (DWR) treatment. A few of the bags opt for microfiber shells for their increased water and wind resistance, a result of packing the threads of the fabric so close together that the elements can’t sneak through. Feathered Friends goes one step further, using a relatively new fabric called Epic. Epic is unique because a permanent, water-resistant, silicone-based polymer encapsulates each fiber of the fabric, guaranteeing outstanding water and wind resistance for the life of the bag.

What about waterproof/breathable shell fabrics? They offer only a slightly higher degree of water protection than today’s new high-tech shells, cost significantly more, and are not nearly as breathable, tending to trap sweat in the down.

A great way to compare one bag’s potential warmth to another is via its fill weight, i.e. how much down is in the bag. Consider the size of the sacks you are comparing along with the quality of the down used. A bigger bag with the same fill weight as a smaller bag will not be as warm, just as a bag with considerably higher quality and lighter down may be warmer than a bag with heavier, low-quality down. So, as a general rule when choosing between similar-sized bags, the model with the highest fill weight should be the warmest.

Full-length zippers help to increase a bag’s versatility — if it’s unseasonably warm, you can turn your bag into a blanket, and when you feel claustrophobic, it’s easy to stick a foot out. Three-quarter-length zippers are an ounce or two lighter (ideal for the weight conscious) but tend to limit comfort, and can prevent you from zipping your bag into a mate’s.

Another key characteristic is open baffles. This lets you move the fill from the bottom of the bag to the top when you need more insulation, and vice-versa, thereby increasing the temperature range of the bag.

After crunching the numbers, a crew of testers and myself headed into the backcountry to see if the zippers ran smoothly or snagged, and if the hood was easy to use, especially in the middle of the night when the pee demon woke us with full bladders. We also checked to see if the bags had insulated neck collars. For some testers, this handy feature helped reduce heat loss from the top of the bag when the hood was partially open.

We did not attempt to answer the slippery question, “Which bag is the warmest?” An almost infinite number of variables would have to be accounted for in order to accurately judge the warmth of the six bags in this review. Eat a triple helping of pasta before hitting the rack and you might sweat all night long. Conversely, bedding down tired, hungry, and dehydrated will probably set you up for a cold night no matter what the bag’s rating. Instead, we tried to establish whether or not the manufacturer had rated the bag accurately. To the manufacturers’ credit, all the bags tested fell within their official temperature range.

Finally, I busted out the digital scale and weighed the stuff sacks. Most companies sell their sleeping bags with a standard mid-weight nylon sack, while a few others include an ultra-light rig. REI goes one step further and throws in a compression sack. It’s interesting to note that an ultra-light stuff sack saves one ounce over mid-weight sacks, and two ounces over a compression sack. The weights listed below are for the sleeping bags sans sacks.

The Test Results

Big Agnes Zirkel, $2792 pounds 4 ounces, fill weight 14 ounces.

Summary: Are you a restless sleeper who always slips off your pad or feels annoyingly confined by the cut of most mummy bags? Well, the folks at Big Agnes feel your pain and design their line of top-notch bags with comfort in mind. Unless you’re a buffed out body builder, the Zirkel’s whopping 67.5 inches of shoulder girth provides all the room you’ll need. To keep you from rolling off your mat during a deep REM cycle, the Zirkel sports an innovative sleeve into which an inflatable pad can be inserted. Not only does this feature keep you and the pad connected, it also eliminates the need for wrap-around insulation. The system is foolproof, but does require using one of Big Agnes’ four mummy-shaped pads (an added expense ranging from $65 to $75) or cutting an ensolite pad to the proper dimensions. The full-length zipper was snag-proof, an insulated neck flap kept cold drafts at bay, the hood cinched down with ease, and the Pertex microfiber shell kept everything moisture-free. The Zirkel even has a pillow pocket built into the inside of the hood. It comes with a standard stuff sack.

Pros: Widest bag tested. Unique sleeve keeps you on the pad. Sewn-in pillow pouch.

Cons: Only Big Agnes pads or modified ensolite pad will fit in the bag’s sleeve.

Overall grade: A-

Feathered Friends Hummingbird, $3051 pound 12 ounces, fill weight 13.4 ouncesSummary: Over the last three decades, Feathered Friends has established itself as a maker of some of the finest down sleeping bags available. The Hummingbird is a testament to this legacy. Its skimpy weight belies its warmth, and its Epic shell had the best water and wind resistance in the review. The Hummingbird’s weight conscious three-quarter-length zipper — eight inches shorter than a full-length zip — stopped at my knees. Those looking to zip two bags together or ventilate the lower regions of the bag while sleeping should consider this limitation. The Hummingbird has open baffles for down manipulation, a snag-free zipper, a well-insulated hood, and comes with a standard stuff sack. The bag lacks a neck collar.

Pros: Epic shell, open baffles, lightest bag tested.

Cons: Three-quarter-length zipper limits versatility. No neck collar. Expensive.

Overall grade: A-

Moonstone 800 Lucid, $2601 pound 12.5 ounces, fill weight 14 ounces.

Summary: As the name implies, Moonstone’s 800 Lucid is almost transparent, thanks to the colorless Pertex X-Ray 1.1 fabric that allows you to literally look in and see the insulation. Apart from the fashion statement, the X-Ray fabric did a great job of reducing the bag’s weight and keeping moisture on the outside of the bag. The 800 Lucid also has open baffles for an extended temperature range and an anatomic hood, but doesn’t come with a neck collar. The 800 Lucid did suffer from a draft tube that kept getting caught under the zipper. Also, the stuff sack is too small, making it needlessly difficult to pack away the bag.

Pros: Open baffles. Nice hood. Trick shell fabric.

Cons: Zipper gets caught on outside of draft tube. Stuff sack barely big enough for bag.

Overall grade: B-

Mountainsmith Vision, $3002 pounds 3 ounces, fill weight 22 ounces.

Summary: Making a bag both light and warm is not an easy combination. Yet, Mountainsmith has accomplished exactly that with their Vision, stuffing it with 22 ounces of downy goodness — the most in the review — while still keeping the bag’s total weight in the two-pound range. Two secrets to the Vision’s great warmth-to-weight ratio are its super-light Dimension Polyant Airnet fabric and the use of a full-length, lightweight zipper. Open baffles and a lightweight stuff sack round out the package. The Vision’s sole downside is that the zipper tends to snag on the edge of the neck collar when completely sealing the bag.

Pros: Light compared to its fill weight. Open baffles.

Cons: Zipper snags on neck collar. Expensive.

Overall grade: A-

REI Sub Kilo+20, $2092 pounds 1 ounce, fill weight 14 ounces.

Summary: If you’re on a budget, look no further than REI’s Sub Kilo+20. It’s far and away the most affordable sleeping bag in this review, and an above average performer. The bottom half of the hood has an extra roll of down sewn into it and rests against your chin when the bag is sealed up. The Sub Kilo+20 comes with a compression sack — a surprising freebie considering the bag’s great price — and the Pertex nylon shell was a sound performer. Unfortunately, the Sub Kilo+20 was the only bag in the review with closed baffles, reducing the bag’s usable comfort range. Also, the zipper had an annoying tendency to snag on the inside of the draft tube, which lacked adequately stiff zipper guards.

Pros: Great price. Comfy hood opening. Comes with compression bag.

Cons: Closed baffles. Zipper gets caught on draft tube stiffeners.

Overall grade: C+

Western Mountaineering Apache Super MF, $3352 pounds 5 ounces, fill weight 19oz

Summary: Western Mountaineering has been making down bags for 30 years and it shows. The Apache’s full-length zipper (which never got hung up on the draft tube) and open baffles allowed for easy temperature regulation. The hood design was the most comfortable one we tested. Even when the hood was cinched up tight and only my nose was sticking out, I could still wiggle my head back and forth, and didn’t feel suffocated. The generous insulation in the hood and neck collar helps make this bag cozy and warm. Western Mountaineering’s proprietary microfiber did a great job of keeping condensation from affecting the down. A standard stuff sack is included. The only drawback to the Apache is its stiff price, which at $335 was the highest in the review.

Pros: Impeccable workmanship. Most comfortable hood of review. Open baffles.

Cons: Expensive.

Overall grade: A

More information

Big Agnes:877-554-8975,

Feathered Friends:206-292-6292,




Western Mountaineering:408-287-8944,