Last summer, Sierra Designs introduced a new ultralight, 900 fill goose down, mummy style sleeping bag called the Cloud 15. Available in one color, a retro-looking cloud white, it weighs just 1 pound 12.3 ounces in the 78″ regular length, making it one of the lightest 15 degree bags available today. I’d never associated Sierra Designs with ultralight gear before learning about the Cloud 15, which seemed like a very positive development, if only because it indicated that such a large company was retooling its products to go after the lightweight backpacking market (see also Sierra Designs Mojo 2 Tent Review.)
Cloud 15 Features
When designing an ultralight sleeping bag from scratch there are a limited number of variables you can exploit to keep the weight down without impeding the utility of the product. These include using higher quality down, shortening zipper length, using lighter weight shell and liner fabrics, reducing the number of baffles to hold the down in place, and shrinking a bag’s shoulder, hip, and foot box girth to cut the amount of fabric and fill required.
Sierra Designs tweaked all of these variables when they designed the Cloud 15, coming up with a lighter weight and/or lower priced tag than other leading ultralight sleeping bags at the same temperature rating including the Montbell Super Spiral Down Hugger #1, Marmot Plasma 15, and the Western Mountaineering Apache MF. That’s pretty impressive for a company that’s just breaking into this segment of the lightweight market.
Let’s take a look at some of the Cloud’s features in more depth:
900 Fill Power Down
The Cloud 15 contains 18 ounces of 900 fill power goose down (see fill power) for insulation. This is really high-end stuff and there are very few manufacturers who use such high quality down. In addition to providing the best weight-to-warmth ratio available, the Cloud 15 compresses down really small in a stuff sack, taking up about 5 liters in this 8 liter sea-to-summit waterproof stuff sack (book and bottle included for scale.)
Super lightweight nylon shell and lining
The Cloud 15 uses 10 Denier nylon for it’s outer shell and inner liner. Denier is a measure of yarn thread size where higher deniers are tougher, heavier, and more abrasion resistant than smaller deniers. As a point of comparison, the lightest weight shell used on Western Mountaineering Sleeping bags is a 20 denier nylon, the Marmot Plasma uses a 10 denier nylon, and the Montbell Super Spiral Down Huggers use a 12 denier nylon, placing the Cloud 15 in good company with other comparable high end sleeping bags.
Low denier fabrics can’t take a lot of abuse, by children for instance. I am quite gentle with my sleeping bags, so the thinness of the shell is less worrisome to me, as long as the fabric and stitching on the sleeping bag has a good DWR treatment. That’s proven to be the case with the Cloud 15 this spring, which has weathered many nights of heavy rain and internal tent condensation without wetting out on me. As you can see here, water beads immediately on top of the fabric and doesn’t soak into it or into the seams between the baffles. That’s a feature I look at closely when evaluating down sleeping bags.
The Cloud 15 has a 40″ zipper to save weight and reduce the length of the draft tube (more weight savings) that is used to prevent drafts behind it. Unfortunately, the Cloud 15 zipper snags all of the time on the outer shell or draft tube lining. It’s easy to un-snag given the slipperiness of the 10 denier nylon, but will likely tear the shell or liner fabric one of these days. A better design would be to place a more robust piece of fabric on either side of the zipper to prevent such snags, like the ones used in Western Mountaineering bags.
The zipper on the Cloud 15 is also only availabel on the left hand side, a curious product limitation. I hate left hand zippers since I am right handed, and reaching across myself in the dark to unzip my sleeping bag is an unnatural motion for me. This a showstopper for me.
One of the hallmarks of a cooler weather sleeping bag is having a chest collar that prevents what is called the “bellows effect”, where you vent hot air around your chest and shoulders when you wiggle around in your bag. While the Cloud 15 chest collar of sorts, it’s really part of the mummy hood and not deep enough to have much effect. You can get around this by tying a sweater around your neck to trap the heat and stay warmer, but it would have been nice if the Cloud 15 included a beefier tube of down over the neck and sterum for this purpose.
Length Wise Baffling
The Cloud 15 comes with length-wise baffling which helps reduce the number of baffles needed to sew the bag and helps cut fabric weight. Unfortunately it also means that you can’t move down from the back of the bag, where is does little good since you’re lying on it, to the front of the bag. You can do this with sleeping bags that have continuous horizontal baffles, which makes them more flexible, in warmer and colder weather. Not a fatal flaw, but a limitation none the less.
Stretch Hugging Threads
Sierra Designs took a page from Montbell’s Super Spiral bags and included flexible stretch hugging thread in the Cloud 15 that conforms to your body shape and moves with you when you thrash around at night. This is a feature that appeals to many side sleepers because it means they can curl up in a fetal position and still maintain proper mummy hood positioning.
I didn’t find the stretchy threads particularly noticeable when I slept in the Cloud, and would rate it as a neutral feature for me, even though I am a side sleeper. If anything, the length-wise baffling makes the bag far more adaptable to violent night thrashing and corkscrew movements because the baffles run parallel to your body rather than perpendicular to it.
If there’s one area where the Cloud 15 really shines, it’s in its dimensions for tall and big people. The size regular bag is 78″ in length (recommended for 6 ft) with 62″/58″/40″ (shoulder/hip/foot) dimensions, while the size long is 84″ in length (recommended for 6 foot 6 inches) with 64″/60″/40″ (shoulder/hip/foot) dimensions. These bags are roomy!
Sierra Design’s Cloud 15 ultralight sleeping bag falls short on the expectations I have for a cooler weather, 15 degree sleeping bag. Despite some excellent high end features, including 900 fill power goose down insulation, the lack of a right handed zipper, frequent zipper snags, and a mediocre chest collar limit the appeal of this sleeping bag for my needs. Given the price of this bag, I’d rather pay a few more dollars and carry a few more ounces to get a more functional bag that suits my preferences. One area where this bag does shine is for tall and stout individuals with its roomy shoulder and hip dimensions, making it an attractive option for Jolly Green Giants.
- Highly compressible, highest warmth-to-weight ratio, 900 fill power goose down insulation
- Lightweight nylon shell fabric with excellent excellent water repellancy
- Only available with left-side zipper
- White exterior gets dirty quickly
- Zipper snags
- Poor chest collar
- Fits to: 6 ft / 183 cm
- Length: 78 in. / 198 cm
- Zipper Side: Left
- Shoulder girth: 62 in. / 157 cm
- Hip girth: 58 in. / 147 cm
- Footbox: 40 in. / 102 cm
- Fill weight: 18 oz / .5 kg
- Total weight: 1 lb 12 oz (1 lb 12.8 oz on the SectionHiker digital scale)
Disclosure: Sierra Designs provided Philip Werner (SectionHiker.com) with a sample Cloud 15 sleeping bag for this review.
Note: The Sierra Designs Cloud 15 has been replaced by the Sierra Designs Cal 13, which uses hydrophobic treated DriDown.
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