Montbell Seamless Down Sleeping Bags

I have an older, rectangular-baffled Down Hugger bag, the version from before they did the spiral baffles. The elastic makes for a much more comfortable bag for the amount of warmth, and I like that the baffles are smaller to keep down from shifting to the sides, but there are definitely cold spots. I use the bag for car camping and sometimes as a comforter on my bed at home when I want to sleep with the windows open in the fall/spring. I don’t trust it below freezing.

I agree that durability is going to be a big concern, but also I would wonder if the sticky thread is really catching all the down, or if the thread becomes less sticky with repeated use or repeated compression/washing. I like the innovation, though. Very Japanese.

At first blush it seems like a solution in search of a problem. A small weight savings for less down, but at a price greater than a comparable Western Mountaineerign bag? That’s not a trade I’ll make for an unproven concept…

It’s a new technology, so being an early adopter could be a risk. But if it works, then there are definitely benefits to it. Lighter, smaller packed size, and no down-shifting are all big positives to me.

Montbell is usually up-front in describing their product limitations and what customer expectations should be. They actually tell certain categories of buyers not to buy their Peak rain shell.

Specs say it is “air tight”

How could one stuff it in a bag if that is the case?

I think that it is only the outer shell is airtight

no baffles- that might be nice….It might help it be warmer with less down since the thickness would be uniform.

Lighter, smaller packed size, and no down-shifting are all big positives to me.

Color me skeptical.

I’ve never found “down shifting” an issue. I think it’s a largely a theoretical “problem” in search of an answer. Also, how Montbell achieves its lighter weight isn’t necessarily through its build technology or materials, but by using less down.

From Montbell:

By designing the sleeping bag in this way we’re able to reduce the amount of down used in the sleeping bag while maintaining the same thermal profile. This reduces some weight and provides a better value to our customers.

So Montbell has saved money in its design by simplifying the sewing, and by reducing down content, yet are offering these bags at a higher price than an equivalent sewn in the USA from Western Mountaineering or Feathered Friends.

None of this adds up…

I’m a big Mon-Bell fan overall though I’ve never used one of their bags.  I appreciate the innovation (at least the attempt at it – we probably won’t know the long term success for several years) but those prices are outrageously high.  I’m with bradmacmt – I’d just get a WM bag.

I used to recommend Mon-Bell for budget “(high-end(ish) bags, I guess I can’t do that anymore.

It’s clear that Montbell says this technique allows the same level of warmth to be achieved with less down, and therefore, less weight.

It’s also clear that this technique must be expensive (at least for now). So even though Montbell might save some money by using less down and not having to sew baffles, the cost of this technique still drives a higher price. Also, we all know that saving weight does not always equal saving money.

@mocs123: Montbell still has all their normal down bags available – it’s not like these are the only models they’ll be selling.

Also, we all know that saving weight does not always equal saving money.

I agree this “can” be true… but does this mean you would buy one John?

I’m happy with my MYOG quilt for cold weather, but I am considering buying the 38F #5 seamless down bag when it comes out. I’ve had issues with cold-spots and down-shifting in warm-weather quilts, so this could be an ideal use-case of the technology and a good way to test it. I was planning on sewing my own warm-weather quilt this summer, and was debating on down vs synthetic.

I did send Montbell an email asking about the long-term durability of their “spider yarn”.

Thanks for the considered response John, and I’ll be curious to know what Montbell’s response is. As you describe it, the #5 might just be ideal for your needs.

It seems to me that while you may be able to reduce weight a bit this way and ensure greater uniformity in temperature – the lack of baffles likely means that you lose the ability to modulate the bag’s temperature. With most bags, shifting the down in the baffles allows you to dial in the right warmth for your situation, allowing for comfort in a wider range of conditions.

I used a Montbell Super Stretch Down Hugger 40F for more than a decade as my primary bag. Those bags are incomparable, in my opinion, to conventional sleeping bags. I could roll around, cross my legs, curl into a ball, flop out a leg, and all was allowed by the elastic baffle system that also easily accomodated worn insulation, allowing me to use this bag down into the 20s With my camp clothing inside. There is nothing else on the market that offers this function and comfort.

But that bag finally wore out and looking at the previous generation of Montbell bags, the Spiral Stretch Down HuggerS, I realized that UL had passed Montbell by. My 40F bag weighed 17 ounces, but to move to a 30F Down Hugger (to compensate for age-slowed metabolism) would weigh cost 7 ounces!  The previous gen Spiral Stretch down Hugger weighed 24 ounces while a EE Enigma 30F weighs 17 ounces in 7D shell and liner fabric.

But now Montbell has a 30F bag that also weighs 17 oz, with similarly light fabrics, and it has a hood. Switching back to Montbell I would gain in comfort, eliminate drafts, have even greater versatility (it too could be worn like a quilt in warm weather, and is much wider…could thrown over dog, etc.) and not worry that additional worn insulation would result in exceeding the quilt’s girth and breaking the tenuous little virtual seal between the quilt edge and the cold.

For me, if it’s durable, the price is probably fair value. Nothing from Western Mountaineering is going to be as comfortable as Down Hugger at equivalent weight. If you haven’t slept in one of these bags it might be hard to see that.

But that Spider Yarn sounds pretty dubious to me. I asked Montbell for the patient # and they’ve not replied, but it appears to be this one: https://patentimages.storage.googleapis.com/d6/0f/c3/5dcc3699b9e0c0/US9380893.pdf

This thread isn’t about the old Montbell stretch bags, it’s about the new technology and construction found in Montbell’s newest bag.

John

I’ve had issues with cold-spots and down-shifting in warm-weather quilts

This is where an Apex synthetic might do the trick for you.

I can’t see Apex making much sense for a cold-weather quilt – simply too bulky and heavy compared to high-quality down.

But as you say, for a lightweight quilt there really isn’t enough down to stay in place within the baffles. Apex solves that cheaply and simply, and because it’s more efficient for this application I’m not even sure there’s a weight penalty.

The Montbell would be a much more expensive and untried solution, seems to me.

Brad, ah, you wrote: “At first blush it seems like a solution in search of a problem. A small weight savings for less down, but at a price greater than a comparable Western Mountaineerign bag? That’s not a trade I’ll make for an unproven concept…”

Problem: Montbell stretchy bags are awesome (and not comparable to conventional bags like those by WM) because they are so stretchy and commodious, but they became too heavy in comparison to ultralight quilts in recent years.

Potential solution: This new Montbell bag, the subject of this thread, that maintains the stretchy, accommodating qualities of the original Super Stretch bags, but at weights that again make Montbell bags ultralight.

Anyone have an opinion on that patent, particularly with regards to potential for durability?

Geoff, looking at these new Montbell bags, with their smooth, seamless exteriors, my mind too went to Apex. But a comparable Apex bag would weigh nearly twice as much, and would not offer the stretch quality.

Notice the instructions for washing. It sounds like the spider filaments inside the new bags are relatively fragile and require special care. Durability, one of the huge advantages of a down bag, remains to be seen.

Montbell has not responded to my email on the durability question – might ask again in a couple weeks. They’ve responded to every email I’ve sent in the past within 1 business day, so it’s possible it fell through given the current world situation.

That said, if they’ve already had hikers use these bags for hundreds of nights, or have done accelerated fatigue tests, that would be good to know.

did montbell ever get back to you?

I use an older spiral-stitched elastic down-hugger for colder weather camping (when I don’t use a quilt), mainly because of comfort. I think it has a 15 degree rating and it’s not terribly light (it is the 800-fill version). Because of my lower back problems, I need to have a small pillow between my legs (lying on side) or under my knees (lying on back), and I shift positions frequently. A standard mummy bag that pins my knees together becomes uncomfortable very quickly for me. The MB bag is a good compromise for me, and if this newer version saves some weight, I would definitely consider it if I replace my old one at some point. I’ll be following this thread for any first-hand experiences.

No, Montbell never responded and I never made a purchase as a result. If I remember my wording correctly, it was a simple question about the longevity of the spider yarn from repeated stuffing/unstuffing.

I haven’t found any real user reviews of these bags either. Only reviews from magazines, which mean essentially nothing.

This thread isn’t about the old Montbell stretch bags, it’s about the new technology and construction found in Montbell’s newest bag.

Right, but several people have said “why not just get a WM or FF bag?”. The point is, those bags — as great as they are — do not have the stretch function. This does. This means that if we are discussing *this bag*, then the only really meaningful comparison is with other super stretch bags. Is it worth the extra money to get this new technology, or should you just get an (old) stretch bag with baffles?

Do you need a ‘stretch’ bag anyhow? Most walkers sleep happily without one.
Who wants to sleep in a straight jacket anyhow? I prefer a loose quilt.

Cheers