MontBell Ultra Light Super Spiral Down Hugger #3 Sleeping Bag Review

that would be absolutely wonderful … but 20F ????

note that the valandre mirage ha 2.6 in of measured loft by BPL …. which according to the chart would give 10F … yet we know that the mirage is en-lower limit comfort rated to -1C or 30F …

id love to know if anyone has taken this MB to 20F without resorting to additional insulating jackets … and be comfortable …

I've used the MB Spiral (long) on several spring and late fall trips into the Grand Canyon, with night time temps dropping no further than the low 40's. I am a midrange sleeper in terms of warmth. Used to be a warm sleeper, am less so as I age.
I've found that once the temp gets down to mid-40s I start thinking about adding layers when using the MB bag. By the low 40s I have added my MB down liner jacket. That makes me a trifle too warm, but I would otherwise be too cold.
I personally don't mind this. I always carry the liner jacket, so it doesn't cost me to have to wear it. However, I have to agree that the 30 degree rating of this bag is very optimistic. I too assume that if a bag is rated at 30 degrees, that means that one can sleep comfortably at that temp without adding extra layers of down.

If Montbell is using the EN_13537 standard then they are also likely using European measurments for fill power. This means that 800 is about the same as 850+ in US terms.

The EN ratings are normally done with some sort of clothing on.

Quoted from http://www.prima-outdoor.com/european-standard/
"Temperature model (dummy)
Temperature model in sleeping bag must occupy such inner volume in sleeping bag that is typical for adult lying on back. Dummy must be 1.5 to 2 m high and its surface must be 1.5 to 2 m2.

During the test, dummy is dressed in two-piece clothing with specific thermal insulation of material Rct = 0.049 m2K/W ± 10 % and in socks getting to knees with specific thermal insulation of material Rct = 0.054 m2K/W ± 10 %. Face of dummy is covered with face-mask.

Let’s assume that tested subject can perfectly take advantage of sleeping bag by adjusting its position and minimizing thermal loss, that he knows limiting factors of sleeping bag against that he can protect himself. "
end quote

So, it can be argued that the numbers are optomistic, since this is a fairly good base/sleeping layer.

I also stumbled across this. Makes for interesting reading…
http://www.snowfox.ru/images/stories/sleep%2520well_pt1_e.pdf
jdm

I am intrigued by the difference in loft between this bag and the Spiral stretch bag. Does anyone want to speculate as to how this bag with the same amount of down has 2.2in of loft vs. 1.9 for the lighter bag?

I think the length difference could be a deciding factor for some. I am 5'11'' and would be not quite ideal for the lighter bag unless I went to the long size. The "super spiral stretch" in regular is the same weight as the "spiral stretch" in long, so it might be a better choice for some people.

There are small differences in down feathers. For example, Eider is considered best and rates a full 900, BUT it only lofts to 800. It is just a better insulator than goose down. Down feathers among species will vary. Average age of the bird. Average weight, amount of fat in the diet, average years temperature, etc. These all effect the down for that year. Usually not that much, but, if you are looking at 700-750 fill down (EN measurements,) you can notice it. This is about 80 points or so. Soo, if one large batch is labled at 750, it can actually be between 670 and 800 (the max by european measurements.) Fill and loft make up the largest part of a bags warmth, but there are other things going on.

For example(not the only one): Oils in the feathers can vary, causing an ounce of 750 fill to be warmer than an ounce of 800 outside of a lab. The 800 cluster looses too much because it is too fragile to suport itself with humid air. An oilier cluster in the 750 does not degrade in the same humidity. (Just one example, the next batch may be different.) Soo, depending on where you hike, you might be better off with a so-called lower fill number. The smart camper knows the difference.

There are simply too many variables to say anything about two individual bags that differ by .3" of loft. Well within expected variability simply due to storage differences. Maybe one bag was under the other, as an example.

BTW, I have an older UL Super Stretch Down Hugger 0. I find that the length is very generous for me at 5'9". Warmth is good to 10F (the coldest I have had it out to.)It is rated to 6'.

But, I believe the author should check with MontBell before saying an "850+" fill upgrade would be good. It may not be possible if they are using the Euro system, as I think they are. It will just encourage them to start playing games with advertising numbers again. Other than that, a really good review.

Thomas
Good Question. I have the same concerns. With my main concern being the internal friction between the threads and the shell fabric opening seam holes, leaking water & down.

I believe it will take longer than the 4 years I have had one to find out…everything seems solid as of this morning…I just checked…

Kathy
Yeah, me too. This bag easily does it for my bad disks and constant tossing and turning.Plenty of room. BTW-You can slip a 60"-70" sleeping pad inside, giving you some extra room. Check out the widths:
From the Montbell site:
Inside Shoulder Girth: 53”~75”
Inside Knee Girth: 44”~62”
I won't say what it does to lofting at max width, though. But a standard 20" leaves *some* room.

LOTS of ROOM…

Addendum: I wonder if these bags do, indeed, have some form of elastic or does the stretch come from just the angled bias of the fabric????? Does anyone know???? If so, then the issue of drying or rotting stretch elements would not be. Comments, if any????

Hi Thomas! About ten years age I acquired the original UL SS Down Hugger #5. It's stuffed with 725 fill power gray goose down, weighs 1 lb 2 oz, and MB lists a usable temperture rating of 35.5 to 52F. All four seasons have seen this bag in use, albeit in winter I have to add insulating layers, including a z-rest on top of my neoair pad, which allowed me to be comfortable to about 27F. The main reason it's so versatile is that this particular bag has no zipper! This innovative feature allows the elastic to snug-up all artound one's body with no heat loss due to convection through a zipper. It's just too bad that MB dropped this feature IMHO.

Anyway, to answer your question, after all these years and nights out in all sorts of weather, the elastic has not shown one iota of degradation. In fact, it will probably outlast me!

I have the Super Spiral Down Hugger #0 and I love it beyond measure. I am a large woman with bust and hip measurements of 48". I'm 5'7" tall. A regular mummy bag was far too restrictive and became stretched tight over my hips if I laid on my side. Most bags literally were like a mummy wrapping on me!

But this bag has incredible stretch. I never feel restricted and I can even sit up cross legged while zipped up cozily in my bag. I sit up in my bag to drink my coffee. Recently I spent a rainy cold day in the tent, propped up in my thermarest chair, cozy warm in my bag.

You'd think this means there is extra air space in the bag. Quite the contrary. The soft fabric falls gently around your body, closing up any air gaps and making a soft warm cocoon.

I can't speak for the temp ratings on either bag, as I've not even come close to 0 degrees with mine. But I can speak about the sizing. An if you're plus sized, then Montbell's Super Spiral series is one of the few options out there for you. This bag truly gives the stretch and room that large people need.

I like it so much, in fact that I am looking to get another one (either the #3 or #5) as a spring/fall/cold summer nights bag. Anyone have any input on either of those?