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

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Home Forums Campfire Editor’s Roundtable MontBell Ultra Light Super Spiral Down Hugger #3 Sleeping Bag Review

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    Addie Bedford
    BPL Member


    Locale: Montana
    BPL Member


    Locale: SE USA

    Yet another great review! A friend of mine sure loves his.

    James holden
    BPL Member


    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 …

    David Booth
    BPL Member


    Locale: Australia

    Great review Will, however I must take you to task. When will BPL admit the optimistic ratings of Sleeping bags in the US market? You say Montbell rate their bags "conservatively" at -1 C compared with the BPL loft estimate rating of -7C for 2.2 inches loft. You then say you needed extra clothing at below
    + 2 degrees. Not to mention you were already wearing a micro fleece etc. That is a whopping 9 degrees C difference to the BPL rating. So the Montbell rating is not conservative compared to real life, it is in fact optimistic by at least 3 degrees C.
    If I buy a 30 degree bag I dont expect to wear extra clothing to achieve that rating. The testing done for the european EN standard does not assume extra clothing and quotes a range of temperatures. It seems Marmot now adheres to this standard. I think all your reviews should state the EN standard for each bag and criticise manufacturers who dont provide this rating. This is the only way the consumer will ever get a true comparison.
    We dont want to know what extreme lower survival temperature clothed with your down jacket and booties. We want to find out which bag reaches its rated temperature honestly.
    I have reached the stage where I do not believe the US sleeping bag ratings except those who are willing to measure the bags against the EN standard.

    Also how can a bag 10oz of 800 down have the same rating as one with 10oz of 850plus down? I think the answer is that some manufacturers have real (or truly conservative) ratings and others are merely unmeasured claims.

    The Montbell bag would probably rate only average (as you said) in this group of sleeping bags when rated under the EN system. However it may well also be an above average sleeping bag in terms of value for money and for comfort. Thanks again Will.

    David Lisak


    Locale: Grand Canyon hiker

    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.

    Travis Leanna
    BPL Member


    Locale: Wisconsin

    I'm not an EN standard buff, but in response to David's post:

    >The testing done for the european EN standard does not assume extra clothing and quotes a range of temperatures.

    This quote is taken from Marmot's website regarding the testing standards:

    "For the EN test, a copper mannequin named Charlie is fitted with 20 sensors and a clothing layer (top, bottom, and socks) that provide a consistent thermal value."

    >You say Montbell rate their bags "conservatively" at -1 C compared with the BPL loft estimate rating of -7C for 2.2 inches loft.

    Keyword: "estimate." Simply measuring loft is not always conclusive, especially when you're dealing with construction techniques that you see in the Montbellbags which differ from standard sleeping bags.

    >Also how can a bag 10oz of 800 down have the same rating as one with 10oz of 850plus down?

    Yes, this seems odd. However, I again believe it has to do with the stretch system.

    Even the EN standards won't be "spot on" for some people. Those tests yield the current best way to consistently measure a bag's warmth, but due to the incredible variation between individuals and the weather conditions they encounter, it's simply impossible to test a bag in a lab and say with 100% certainty it will be warm enough for everyone in any condition down to its rated degree.

    I've experienced being cold on one night and warm on another in the same sleeping bag, and in almost identical conditions.

    James Marco
    BPL Member


    Locale: Finger Lakes

    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
    "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…

    Elliott Hollander
    BPL Member


    Locale: Georgia

    In response to eric's question, I own this bag and have used it in temps down to 21F. I definitely needed extra insulating clothing inside the bag at that temperature to stay warm (down pants, down socks, patagonia nano top). With this setup I was a touch too warm at 21F, and slightly adjusting the zipper/draw cord helped. That said, I have also been way too hot (sweating!) wearing insulating clothing in this bag at 30F. Overall I love the bag for it's lower wieght and soft material.

    Edit: NOTE: I have the Spiral Down Hugger #3, not the SUPER Spiral version – though as Will points out the only difference is zipper length and girth.

    Douglas Ray


    Locale: Pacific Northwest

    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.

    Kathy A Handyside
    BPL Member


    Locale: Southeastern Michigan

    Great review! Back in the '70s, when I first got into backpacking, I bought a Sierra Designs Cirrus sleeping bag. I have always found it to be very restrictive but that was the way all the mummy bags were. I'm a side sleeper and I move around when I sleep, so I never got a good night's sleep in my SD bag. When MontBell came out with their super stretch bags, I was so relieved! At last, I will be able to get a comfortable sleeping bag that will enable me to get a good night's sleep!

    As soon as I've finished saving up the money, I will be getting one of these bags.

    James Marco
    BPL Member


    Locale: Finger Lakes

    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.

    F. Thomas Matica


    Locale: Vancouver, WA

    Down bags are know for their longevity if properly cared for.
    I'm wondering about the elastic/stretchy cords or material in this and other bags of this type. This "bungy" element would seem to have a limited life, maybe also limiting the life of the bag. Could it dry(or otherwise)rot and then not perform sooner than the down or fabric? Is that an issue even if it does??? I don't know. Comments?????

    James Marco
    BPL Member


    Locale: Finger Lakes

    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…

    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…

    folecr r
    BPL Member


    I've used mine for spring/summer trips and have been comfortable in it down to the mid 30's. I used the Big Agnes insulated air mat which might be why the temperature rating worked for me.

    The fabric of my bag makes this horrendous crinkling noise! When I'm inside the bag and move around, it almost feels like I'm inside a bag of potato chips. The noise was loud enough that I actually woke up a couple times just because of it.

    Perhaps this is to do with the fact that I used it on the Big Agnes mat? Maybe others are using it with softer faced mats like the Z-Lite? I don't know.

    Great bag for spring/summer weather. Except for that noise.

    F. Thomas Matica


    Locale: Vancouver, WA

    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????

    James Marco
    BPL Member


    Locale: Finger Lakes

    According to one review, maybe it was on the MontBell web site(?), yes.

    I believe it is elasic monofiliment, not rubber. (My wife has had it in her beading supplies for a bit more than ten years. The neclace she made is still in good shape.) But, I am a little reluctant to take mine apart to confirm this.

    Monty Montana
    BPL Member


    Locale: Rocky Mountains

    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!

    John Devitt
    BPL Member


    Locale: Colorado

    I was worried about about the long term relilability of the elastic. I own a 1 generation #2 UL SS with 725fp. The elastic still works great. As far as the temp rating, I found it to be off. I am a cold sleeper and have the same results in my WM bags. I just account for this buy using a bag that will keep warm in the temp range I need it for. I had the box baffles removed and more 800 fp added to the bag. I now I a really comfortable bag with continous baffles and 7' double layer loft that weighs 2lb 7oz. This works for me, and the unexpected weather the mountains can throw at me. Thanks for the great review!


    Ginger Allman


    Locale: Ozarks

    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?

    Eric Osburn
    BPL Member


    Any more long term comments on the durability of the stretch material?

    Outdoor gear lab mentioned that their bag started puking down after a season of heavy use. Has anyone else had similar issues?

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