I'm in the process of looking for a sub-zero synthetic sleeping bag for some of my longer outings in cold, moist conditions. I do a lot of backpacking and mountaineering in NH and on numerous occasions I've lost the loft of my down bags.

I currently have a -40 down bag from EMS. I wouldn't have bought it accept for the extreme deal... picked it up for 99 bucks at a local EMS and I actually love the bag. I also have a 25 degree down bag that I use in the fall.

I'm having trouble finding a large selection of -20 synthetic bags though. Any recommendations?

I am also in the market for the same thing. And i also am having a hard time finding many options. Pretty much TNF has a decent bag at 4lbs, not bad for synthetic and $250? Not excited about TNF but at $250 who cares right.

I am pretty sure i am gonna go with a FF -20 down bag as i want the packability and weight as i am gonna carry a 30L pack all winter. I really wonder how low i can get with MY Peak XV and my Summerlight?

I've actually heard bad things about the warmth of TNF -20 bag. I think it's called the Tundra. Pretty poor reviews and I have a buddy that had to return the bag to REI as it did not live up to the temp rating at all. I've heard multiple people say it's more like a 10-20 degree bag.

Which I can't do up in the Whites in the winter.

Slightly heavier, but I've been looking at this:

http://www.mountainhardwear.com/Lamina%E2%84%A2--15-%28Long%29/OU8447_L,default,pd.html

Yeah the synthetic TNF -20 F bag is the Tundra. I looked at one (there is no way I would trust taking it in the middle of winter) and it is very heavy and lofted up less than my 2 lb, 20 F sleeping bag. Maybe at 10 F it would be OK, but it does not compress very well either.

I haven't used a Kelty Mistrail -20, but for $50 on sale and with decent reviews, it might be worth considering. Not lightweight, at ~6#, but I can't imagine any -20 synthetic could be less than 5+ pounds no matter what. I'd expect most to be ~6 if they were going to have enough insulation to work.

I'd also consider the MH Lamina -30 -- If you're looking at those temps, I'd want a little margin for error, and that might be a huge difference in comfort. At 5#, 9oz, it's a good weight for what it is.

The other thing I would think about is a two-bag system. A zero-degree synthetic over an ultralight down bag might give you the best of both worlds, and you probably already have an ultralight down bag you like. There are some zero-degree Primaloft bags that I'd consider very nice by the standards of synthetic bags.

Last consideration would be a zero-degree synthetic bag and an alpine-level full body suit or pants/jacket combo that would add 20+ degrees of warmth... that would also give you around-camp functionality... just think systems. I wish you well in your search.

I'll second the MH Lamina minus 15. It held up well for me in cold wet conditions living in the snow for a week, to include dips subzero. For a synthetic bag, it seemed to hit a sweet spot in terms of weight, price and performance. The minus 30 version seems to tip into the "too bulky" category, but if using a pulk it's a viable choice.

Edited by sgaioni on 10/18/2011 05:36:46 MDT.

I foolishly bought on sale two northface synthetic bags, weights seemed good, the Lynx and the orion, I think, rated at 40 degrees and 20 degrees respectively. Those ratings are not even remotely close to reality, could easily be 15 degrees off. The orion which even the sales guy at their outlet tried to steer me away from, I doubt is more than a 35 degree bag, at best, judging by its (lack of) loft. I should have checked the loft, but ordered the Lynx online trusting my reasonably good experiences with 1990s era northface gear. Northface used to be good, I have an old Cats Meow 20 degree, heavy but honestly rated at least. I could feel the Lynx fade out at around 50 to 55 degrees on a recent trip, and when it dropped below 50, I was having to start wearing clothes to keep warm enough. Fraud? I think so, especially given that Northface has sold properly rated bags not so long ago in their history.

I assume their other bags are as bad.

Edited by hhope on 10/17/2011 11:39:34 MDT.

I don't think that there is a synthetic bag to be found anywhere that will keep you warm at -20F and that also weighs less than six pounds. I have an Integral Designs 0F rated primaloft bag that I would trust to maybe 15 above, but it appears that ID no longer makes sleeping bags for the general public, although they still have some listed for government and military buyers.

Edited by kidcobalt on 10/17/2011 11:59:15 MDT.

My thoughts on synthetics are mainly based on using a pair of ALPS Mountaineering Slick Rock bags... primaloft insulation, 0-degree rated. I've been warm and toasty in them close to zero degrees (it was 5 degrees when I woke up in the morning, unsure if it got colder during the night), but that was with a coolmax liner and wearing a synthetic insulating layer, softshell pants and jacket and a fleece hat... so nothing too extreme. That bag weighs just under (62.5 oz) 4# in the regular length, a little over (67.5 oz) in the long.

My wife slept fine in hers as well, in a similar setup. We were each using a POE Eco Thermo 6 with a Z-Lite on top, so we weren't losing heat to the ground.

I would trust the Slick Rock bags down to about 10 degrees without a liner and with minimal extra clothing. With down pants/jacket/hat/socks, I'd trust it down to it's 0-degree rating for comfort, and I think you could survive colder than that.

I'm guessing other Primaloft bags should provide good comfort/warmth, but I'm not sure on who makes Primaloft bags at sub-zero temps.

It's not a -20F bag, but this guy has great things to say about his MH Lamina 45 bag; maybe the design and insulation make for a winner in the colder models too:

http://www.hikeabovetheclouds.com/lamina-45-review/

I've got the TNF Tundra, and I think it is a legitimate choice in this range.

I've spent many happy nights in it, probably not to -20F but certainly a good many in the -5 to -10 range. I live in northern Vermont and I spend lots of winter time here as well as in the Adirondacks and the Whites.

You have to be a little bit skeptical of people's reviews of any winter bag, since lots of people don't know how to sleep in the cold. Do you put a hot water bottle at your feet? Do you use 2 inches of insulation underneath? Do you use a VBL liner? Do you use the draft collar and the hood as they are meant to be used? If you know how to use it, this bag is fine. If you don't, no bag will keep you happy at 20 below.

It's big, but it compresses to a plausibly packable size, and for its bulk it's not actually all that heavy.

Dude- long trips, cold as hell- VBLs all the way.

if its your loft you loose, at those temps, its your sweat. Well... you said snow cave too....

VBL + Bivy
0deg bag

The jump from -5 to -20 is a big one.

I do know how to sleep in the cold and was at -31 F last winter. I plan to hit -40 (or lower) this winter if possible.

Water bottles and VPL's are all good and well but should never be "needed" to make a bags stated temp range.

wow you think only 5 deg from 0? hmm

Well I was kinda getting at that, from his post, its not the temps its the loss of loft over the trip. So I was trying to solve the actual problem rather than compensating for it with a huge bag.


---it looks like he's already using a big ol bag. maybe keep that bag and VBL bivy up to keep it dry.

Edited by WoodenWizard on 10/17/2011 17:03:11 MDT.

steve,

have you considered using a VBL and a light synth quilt/overbag over yr down bag in winter

as everyone and their cat knows ... im a proponent of using synth bags and puffies in more moderate, ie rainy, conditions

but in winter the weight savings of down and the lower bulk are quite high

a synth overquilt would protect decently from outside and inside condensation, and a vbl would stop the body vapor from getting the bag damp ...

With Tim Marshall's enLIGHTened equipment back up and running, I'd recommend talking with him about a piece of custom gear. The cuben fiber Climashield Apex quilts he makes have the best weight/warmth ratio of any synthetic solution I know of, and I think he's also very good about custom gear.

He doesn't have any synthetic bags listed below 15-degree ratings, but extrapolating from what is there, it looks like a theoretical cuben fiber -20 synthetic quilt could weigh close to 4#, which would easily be your best possible weight for those temps.

I'd contact Tim and see what he recommends and how much a custom bag would cost.

Well maybe I shouldnta posted... Never slept in a snow cave... are they that humid? even at -something degrees?

+ 1 on the -30 degree lamina.

I own this bag and it is generously sized, so you can wear layers and bring in gear to warm up with you. I have used it down to -14 F and hope to go lower this winter.
In My search last year for a good bag, It was a toss up between this and the north face dark star -40. Both are good bags.

Enjoy,

Dave