Help with decision on MontBell Super Spiral Burrow

I am looking for a very unrestricting sleeping bag and Mont Bell ones seem to be good candidates due to using specific stitch design and stretchy thread.
I am wondering how strongly this stretchy thread will squeeze me.
If I get into the bag wearing puffy jacket and pants, will the thread in the bag exert too much pressure and compress the clothing I am wearing thus eliminating its insulating value?
Or is it just a gentle pressure that will not eliminate loft in clothing I am wearing?
I am trying to decide between a large semi-rectangular (or even rectangular) bag in which I will have plenty of space and be able to put to good use my puffy clothing as temperature dictates, and Mont Bell, the advantage of Mont Bell is lighter weight, but the pressure of thread would negate any advantages if that stretchy thread decreases loft of my cloths.
Does anyone have some experience with this bag and could say if I should stay away from it considering my predicament?

I have one and its not that tight on me (and I'm a big fella). I have moved on to a quilt so I have a lightly used Mont Bell Ultra Light Super Spiral Down Hugger #3 Long Left Zipper for sale

I am curious about a couple of things. Why would you want to wear a jacket inside the bag? What temperatures are you trying to sleep in?

I never use a bag in three season conditions because I found them to be too constricting. For temperatures down to the mid 20s (f) I use a quilt and don't require additional insulation. Some quilt users will get to 0 before switching to bags (there are 0 degree quilts).

Too many layers can be self defeating. If you bundle up so much that it restricts your own blood flow, you'll have trouble staying warm.

Hi Lori,

The reason for wearing the jacket inside the bag is to make the most use of every item I carry with me, I want as little dead weight as possible. Temperature could be around -10C.
Since I need an insulating jacket to carry with me anyway, I would rather get a lighter sleeping bag and augment its temperature rating with clothing.
I am eying 40F rated synthetic Montbell, and it seems to be a good candidate if it is not going to reduce the loft of my clothing. With this approach I can go down to much lower temperature using lightweight bag. It would not be too many layers, and far from restricting blood flow.
I tried sleeping a couple of times without any bag at all, just a good insulating pad and synthetic insulation cloths and loved it, with a light bag on top of that I would be in heaven.

Unless you have the metabolism of a polar bear, I don't see this working out. I have used my parka over my bag, not in it and that works fairly well, but not to compensate for a 25 degree temp differential. -10C is +14. I do not see how a +40 bag and parka will work at that temperature differential unless you have a parka like mine (or similar) which is a TNF Baltoro (new model renamed Himalayan) which is a $600 down parka designed for sub zero temps. I have used a -5C (+23F) bag in temps down to around -10C with an MEC overbag or my parka on top wearing Capilene midweight base layer top and bottom and been warm and I am a cold sleeper. My parka weighs as much or more as a lot of sleeping bags.

I've never used a quilt, so I will defer to those who have. Ray Jardine makes inexpensive quilt kits and he has used them for years in cold weather. All the info is on his website (www.ray-way.com). I think a few of the members here may have one.

Tom,

My experience tells me it would work. The nights I mentioned, spent in my lofty clothes and without sleeping bag, were quite cold, I cannot say for sure how cold but certainly below 0C since the water in bottles I had inside of tent froze.
I was getting somewhat cold during early morning hours, especially my feet as they were not properly insulated (just some thick wool socks).
If I had a light sleeping bag to crawl into with all my clothes on I would be quite comfortable.
It all makes sense to me, there is much thinner layer of air you have to keep warm when wearing properly sized insulating clothes (puffy jacket and pants, socks, gloves) in comparison to sleeping just in a bag with some midweight clothing. Quilt would not work for me, I move a lot during the night, and I would keep losing warm air as I toss around.
There is one more advantage to this approach I have, I also tried one of those extremely light emergency bags with reflective surface, those weight nothing and work incredibly well, the only problem is condensation inside, so if it gets extremely cold I could put bag inside it, the condensation would wet the bag and not my clothes. Such contraption would let me sleep in even colder environment.

I'm a latecomer to the thread, but for what you're suggesting (based on your later responses), you might want to look at the Western Mountaineering Mitylite bag. It's semi-rectangular, hoodless, and has two zippers (side and bottom) so you can unzip it to use like a quilt, but still leave the bottom zipper closed to make a footbox. It's a 40 degree bag, but I think it's conservatively rated. Sleeping in longjohns (top and bottom), down booties, down hooded jacket, down pants and maybe down mittens, on a Thermarest Prolite 4 pad (3/4 length), in my backyard, I stayed warm to about 15 or 20 degrees - at which point I got chilly and went inside. I can't remember if I was zipped into the bag or using it quilt-style, with the edges tucked in pretty good.

The quilt is for me, precisely because I move so much. I hated being trapped and wrapped up in a sleeping bag trying to get out. With quilts I'm able to tuck back in and hardly need to any more - since I sleep so well with them I only wake up a few times in the night.

The other half of any sleeping system (for ground sleepers) has to be a good insulated pad. If you don't have one that would be why you are cold sleeping in just the jacket and pants. The insulation underneath will compress and leave you cold no matter what you use.

I don't know what emergency blanket will keep you comfortably warm below freezing - never met one warm enough to even be part of my usual sleep system. But a vapor barrier is a different sort of approach and I'd only consider it in subzero temps, which I won't do if I can help it.

Well. all I can say is try it out and see what happens. I personally don't like the idea of sleeping in my clothes, but if that works for you, then go for it. One thing I don't like about your idea is the possibility of getting the inside of my bag any dirtier than it would otherwise with just me and my base layer inside it. I've tried sleeping with a jacket on and find it really annoying since I tend to thrash about a bit before I fall asleep.

There really is no one answer that is perfect for everyone, unless, of course, you are Douglas Adams, in which case the answer is "42." And yes, I will explain that to anyone who asks.

So, I take it that you consider one of the ten essentials to be your towel?

Merry Christmas, Tom.

I crawled into a MontBell spiral bag wearing my winter shirt, pants and socks at the store and was surprised to find it roomy enough to allow for my tossing and turning. The bag was not oversized. Sometimes I need to get up in a hurry at night and check on the llamas so I sleep in tight fitting undergarments, but never in a loose fitting jacket. During the coldest weather I drape my down jacket over the bag.

I was considering replacement of my Sierra Designs Rip Van Winkle which has elastic around the knees. I did not replace it and that is my only experience with the MontBell.