Center zip sleeping bags?

[Joe S]

The Stoic Somnus 30 center zip bag seems like a great deal when Backcountry has it on sale. The ability to use it like a quilt when unzipped is a plus. But I also sometimes sleep on my stomach, not on my side, and would the zipper drive me crazy when using it in bag mode? Any folks have experience with this?

[Steven McAllister]

I have used a center zip bag(Exped Wallcreeper) and quite liked the zipper orientation once I got used to it. I am mostly a side and back sleeper, but occasional found the zipper underneath me from tossing and turning in the night.

I didn't find the center zip uncomfortable when I laid on it. The draft tube on mine seemed to cushion it enough, but can't speak for all bags.

I have used center zip and side zip bags for quilts and don't think the center zip is that much better for that use though.

My Wallcreeper worked especially well as a two person quilt and that is usually what I use it for.

[Jerry Adams]

I put the zipper on my hybrid bivy/quilt in the center which would be much the same as your bag

I think this is much better. You can open zip and push to both sides. Gives good ventilation. Keeps the open bag out of the dirt.

Theoretically, there's a cold spot at the top but I haven't noticed. It might help that I sleep wearing clothes under, so that cold spot is sort of averaged out.

I don't know why they don't put all zips in the center. I think maybe it's just convention. They put the zip on the side because that's how everyone does it.

[michael levi]

Twist the bag 90 degrees. Problem solved. It's more of a mental thing than a physical altercation.

[Roger Caffin]

I prefer a centre zip too. It makes for a better quilt design. I do not find having the zip under me when sleeping on my face to be even noticeable.

Cheers

[Jerry Adams]

I may be dense here, but I don't understand the comment about the zip under you from two people now

The zipper is on top of you

[Nico .]

I had one, a Golite Adrenaline sleeping bag, with the center zip. It's actually a great design for back and side sleepers as it reduces the chances of laying directly on the zipper.

My big gripe with the concept (or at least the Golite version) was that the center zip was really short, so you were limited in how much you could vent or open up the bag. Seems like the zipper only went down to about my waist. If it's cold enough to be in the bag, this isn't a big deal, but if the bag is a little too warm, there was no way to easily hang a leg out the side or open up the bag any more.

I ultimately switched to quilts full time and haven't looked back since. I like the increased venting options. I hang on the Golite bag as a loaner for friends.

[todd]

"I may be dense here, but I don't understand the comment about the zip under you from two people now"

Jerry: Some bags have the zipper on the bottom, ie: Zpacks.

[Kimberly Wersal]

Or, if you sleep on your stomach, the zipper is under you.

[Jerry Adams]

"Jerry: Some bags have the zipper on the bottom, ie: Zpacks."

ahhh

that seems weird

how do you open the zipper if you're sleeping on it?

[Roger Caffin]

> how do you open the zipper if you're sleeping on it?
Very very complex.
You roll onto your back.

Cheers

[Jerry Adams]

But if you roll on to your back, your back would then be on top of the zipper, and it would be difficult to manipulate the zipper with your hands behind your back

I guess you could sit up, open the zipper, then lay down

Seems like it would be easier if the zipper was on top

[Nick G]

I really like the center zip bag.

The only issue is, it's hard to find a center zip bivy to go with it, if you're into bivy sacks. Has anyone found one?

Borah tells me that a center zip bivy was impossibly awkward to get into, so they don't sell it–I can't imagine it being any different from a center zip bag, but they're the experts.

[michael levi]

I just thought i'd throw a picture of the Zpacks quantum bivy. BTW Nick, what center zip bag do you use?

I have a Stoic 30, I don't mind the center zip as it saves weight by the zipper being smaller. There are upsides and downsides to it. First the upside, it is lighter than a full side zip and warmer. Heat has less of a chance to escape from the foot area if theres no zipper. Downsides are venting options by the feet when its hot. In this case I unzip the center zip and put it on top of me like a quilt, and lay directly on my pad.

[Roger Caffin]

Hi Jerry

> But if you roll on to your back, your back would then be on top of the zipper
Huh????
No, when I roll over in a SB, the bag goes with me.

Cheers

[Michael Cheifetz]

@jerry- a bit of confusion here. The OP was about sleeping bags with a top zipper in the middle (eg stoic, nunatak alpinist, golite adrenaline) in these cases the zip is on your chest… And if you roll to sleep on your stomach it is UNDER you
The Zpacks is a hybrid quilt where the zip is in the center of your back and you sleep on it that way

Re usability- I have 2 nunatak bags with center zips and love them. I made zips very short and indeed venting is an issue… But I usually sleep in temp ranges that are. It that wide and would rather have more bags and take the right one. Of course you can vent by wearing your puffy jacket and getting out of the bag slightly if it's really warm. I guess u could also have a short zip in foot box

[Jerry Adams]

Okay, I see now

When I roll around in a sleeping bag, it stays in place so the top stays on top

[Steven McAllister]

Re: "When I roll around in a sleeping bag, it stays in place so the top stays on top"

I have sleeping bag that you attach to the sleeping pad and because of this, it can stay in place like a quilt. It is snug fit so I don't use the tiedowns because they made me feel trapped. Mu tighter bags turn when I do.

For cold weather, I find that a sleeping bag that fits snug when I wear extra clothing inside is warmer, but will move with me when I flop from side to side and so the zipper never stay in one place.

[Nick G]

Michael–I use a Golite Adrenaline 1+ season bag. Thanks for picking that up about the Zpacks bivy–I sent a note to them to see about using less expensive fabrics to reduce cost. If anyone happens to have a used one for sale, let me know.

Basically, the upshot is that unless you custom make a bag that doesn't have any zipper at all, it will always be possible to roll over onto your zipper. I don't sleep on my stomach, so I can't say for sure, but I will say that its not an issue to leave the bag where it is and roll over on my side. You do get a face full of bag, but that's life in a mummy bag. I didn't like having a side zip bag because it was very painful to roll over onto, so that was a deciding factor. A center zip is, for most people, the most difficult kind of zipper to end up on top of.

[John Vance]

All of this is why I moved to quilts.

[Sam Farrington]

The manufacturers prefer side zips because that is where they put the seams.
They put the seams on the sides, because that is where it is cheapest to put them.
Side seams require only a simple sandwich, a very simple design, so cheaper.
A bag without side seams is warmer, but much more difficult to design and construct.

But without the side seams, and with a center zip and seam, the zipper is much easier to operate (at your chest), and less likely to get under you. Maybe it doesn't bother Roger, but I find it a PITA to have to roll about when barely awake to get at the #$%@ zip!
A side zipper is more likely to get under you because it is halfway there to begin with.

Agree that the center zip should be longer, all the way to the foot box, so a reverse slider there can be zipped upward for ventilation. The separating slider all the manufacturers use is not necessary, and is a @#$% to reconnect if it gets separated in the night. But the manufacturers put it there anyway so bags can be "mated," and have sex appeal.
And the manufacturers use heavier zips to minimize returns, making a full length zip quite heavy and a nonstarter.
Again, it is all about $$$.

If you want to keep the hood where it was designed to be in order to keep warm, you can't twist the side zip around to be on top.
So i live with it, because the MontBell spiral bag I use provides so much more warmth for weight, confort and other good features than the bags I used before.
Thank you Ray and BPL for cluing me in about the MontBell bags.

I use a bag rather than a quilt to get the most warmth for weight.
Someday (hopefully before the MontBell wears out) I will have the full center zip with the best featherweight DWR nylon, and the best synthetic, or down fill if the DWR down treatments prove out.
But I'll have to make it myself. It is not profitable for the industry to make.

[Mary D]

I grew up using a center zip sleeping bag. I also learned at an early age to take the bag with me when I turn over, so the zipper (and more important, the hood opening) stays where it started relative to my body. And yes, the zipper will be under me if I'm on my stomach, but I rarely sleep that way.

I agree about side zip bags being more awkward, but after many many years I've gotten used to it. I do like the full length zipper for ventilation.

[Roger Caffin]

Hi Sam

> Maybe it doesn't bother Roger, but I find it a PITA to have to roll about when barely awake
> to get at the #$%@ zip!
Well, it's been a long time since I used a SB instead of a quilt, even in winter.

As for taking the SB with you when you turn over, think large green (or colour to your preference) caterpillar.
And yes, taking the bag with you means your nose and mouth stay at the opening, with all the good moisture control that implies. (ie, don't breathe inside your bag or you will get condensation in the down.)

Cheers

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