Sierra Designs Vapor 15 Sleeping Bag Review

A very thorough review. However, I'm a side-sleeper and a restless sleeper. I need a bag that has some flex to avoid feeling like I'm being held hostage in my sleeping bag. If this bag had the Sierra Designs flex, I might consider it. I will continue to save up for a Mont Bell Super Spiral down hugger bag instead.

Something seems to have gone awry with your metric conversions: a centimetre is approximately 2.54 cm therefore;

5'10" = 177.8 cm (usually rounded to 178 cm, not 180/1.8m)

6' = 182.88 cm (usually rounded to 183 cm, not 180/1.8m)

6'2" = 187.96 cm (usually rounded to 188 cm, not 190/1.9m)

"I have not personally tested any of the other 10-20 F (-12 to -7 C) rated bags in the table above, so I can’t compare them other than by the numbers. One main difference is the Vapor 15 has a half-length zipper, while the others all have a full-length zipper"

The WM Versalite also has a half-length zipper.

Thanks for the excellent review, Will. It's great to see another manufacturer moving further in the direction of ultralight, high quality gear.

In discussions of bag length, I don't think I've ever seen acknowledgment of the importance of foot length, and ankle extension. A person with a longer foot, and a looser ankle, will have an overall body length considerably longer, when lying on their back, then someone with a shorter foot or a "stiffer" ankle. So in a shorter bag, a longer-footed person will more easily have the feeling that the bag is too short, as they feel their toes pressing agains the foot of the bag, and their head against the hood. I've never done the research, but I'll bet the difference between a stiff-ankled size 9 foot and a loose ankled size 11 foot could be easily two inches.

Another thing to note, though I haven't seen the Vapor, is that the Marmot helium is, as I remember, generously cut (i.e, large cross-sectional diameter), and the vapor looks more compact, judging from the photos. So the average down density per square inch of bag surface, which is, I think, more important than the total down in a bag, might favor the Vapor.

The zipper on the WM Versalite is definitely full-length, as it is on all their bags other than the Highlite. Considering the Vapor 15 is essentially the same price ($440 for the SD, $455 for the WM) I believe the Versalite is a much better value. It's performance is legendary in this community.

Yup, Versalite has a full length zip. I believe it's an MSRP of $440 though for regular length. Of course, you're far more likely to find a deal on the SD bag for what that's worth.