Planning a fast and light cold weather adventure? The Mountain Hardwear Mtn Speed 32 employs a new type of nylon to become the lightest sleeping bag capable of keeping you warm in freezing weather.

What's It Supposed to Do? This is a down-filled sleeping bag designed for people who are traveling fast and light in the backcountry during colder temperatures. It was designed in collaboration with Ueli Steck, a world-class speed climber, for use as an emergency bag on his high altitude climbs. Something light enough that it wouldn't slow him down during his fast vertical ascents, but warm enough it could save his life in extreme weather.

With its 32° temperature rating, its 15.7 oz weight makes it the lightest full-featured sleeping bag in its class. "Full-featured" means it has a hood, drawstring, zipper and zipper baffle. All the stuff you take for granted that helps a sleeping bag actually keep you warm.

The Mtn. Speed's slim shape reduces weight while maintaining comfort and warmth.

How's It Supposed To Do It? There are a combination of factors at play that contribute to the Mtn. Speed's amazing warmth-to-weight ratio. First, its shell is made from Mountain Hardwear's revolutionary Ghost Whisperer fabric — the lightest nylon commercially available. Ghost Whisperer fabric is windproof, down-proof, and water resistant. The Mtn. Speed uses 850-fill power, water-resistant down. Additionally, the bag uses a ½-length #3 YKK zipper in order to save weight.


The Mtn. Speed utilizes a 1/2-length #3 YKK zipper.

How Does It Perform? This bag is light! It weighs 50 percent less than other "lightweight" sleeping bags with comparable temperature ratings and fill-power. It's lighter than a lot of down jackets. It's also incredibly compact. The Mtn. Speed packs into a 1.5 liter stuff sack. This factor alone revolutionizes the way that you can pack, because it takes up so little space.


We put it to use in sleeping in the High Sierra when temperatures dropped near its rating and we did not get cold (keep in mind, everyone sleeps differently.) When we summited Whitney at 3am on July 4th, temperatures on the summit were near 20°. Combined with our layers, the bag was invaluable for keeping warm.


See that material hugging the zipper? It constantly gets in the way.

My biggest issue with the Mtn. Speed was with the zipper. Not the length or the size (the Sea to Summit Spark SP1 has a shorter ⅓-length #3 YKK zipper that's great), but with the material underneath it (pictured.) It constantly snagged unless the two sides of the zipper were aligned perfectly straight. Once it snagged, it could become difficult to unsnag. This was especially frustrating after a long day of climbing or being on the trail.


Some buyer reviews have complained about the lack of down filling. When you first pull out the bag, it does appear rather thinly filled — there were a couple of darker spots in the unit I tested which could signify less-insulated areas. However, once the bag had time to loft, it became very full and said dark spots were no longer present. Anytime you're unpacking a down sleeping bag from its stuff sack for use, give it a minute-long shake to help those feathers spread out.

The Mtn. Speed packs down into a 1.5L stuff sack.

Adventure Ready? When you're counting ounces, whether for an ultralight backpacking or climbing objective, lightening your "Big Three" (Shelter, Pack, Sleeping System) is one of the quickest ways to shed weight. No other 32° sleeping bag on the market can compare to the warmth-to-weight ratio of the Mtn. Speed. As with any sleeping bag, when temperatures drop lower than the temperature rating, you can extend that by wearing base layers, hats, gloves, and insulating layers to bed. Using that technique, this bag gains even more versatility in cold weather while remaining incredibly light and compact. I can't wait to take it snow camping.


Mountain Hardwear Mtn. Speed 32 — $480

Photos: Chris Brinlee Jr.

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