Zpacks

[Bob Gross]

It seems to me that Zpacks has picked up a bit of business in ultralightweight shelters and ultralightweight backpacks. What I do not hear or see is any discussion about their ultralightweight sleeping bags. Is there a reason for this, other than maybe they are just too new?

I own seven or eight sleeping bags already, but the "numbers" on the Zpacks (summer) bags look very good. They are not inexpensive.

–B.G.–

[Link .]

here is one discussion,still new so not real in depth

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=53421

[Dan @ Durston Gear]

The specs look quite good to me. I love the use of extremely light nylon (ie. 7D) in sleeping bags. It's the perfect application for these fabrics.

These bags look like good options to me, although EnLIGHTened equipment has some amazing prices on their nice stuff. That might be nabbing some sales.

I personally have come to love a quilt that you can open up all the way into a blanket. My new BillyGoat/Virga Outdoors quilt has this functionality, and I really like it when I'm in mild temperatures. Obviously when temps get close to the rating of the quilt then you want to button it up.

[Bob Gross]

EnLIGHTened equipment does not offer sleeping bags, so forget that one.

I would certainly hate to drop over $300 on a sleeping bag that was selected just by the numbers. That's why real user opinions can be good.

Up until now, for summer use I have a Mountain Hardwear Phantom 32, and it is OK for me. But then the Zpacks numbers would allow me to reduce a number of ounces…

–B.G.–

[Dale Caldwell]

I recently bought two bags from Joe and have only used them once but it was in cold temperatures. We didn't have thermometer, but the forecast called for an 18 degree low in lower elevations than we were in. I purchased a 20 deg with two extra ounces of down (trying to get to 15 deg) and a 30 deg with one extra ounce of down (~27 deg?). My girlfriend and I zipped them together to use as a quilt, though we ended up tucking what we could under us. Not having much body fat at all, I opted for the 15 deg side of the quilt. The beginning of the night was cold and I had to add clothes in the middle of the night. I did feel like most of the cold was attributed to the pad I was on. In these temperatures, it is hard to find a lightweight pad that will really keep you warm. After adding some clothes, I did sleep much more comfortably and my girlfriend said she stayed warm on the 27 deg side of the "quilt".

I usually don't want to hear how excited someone is about their new piece of gear when reading reviews from those who haven't put it to good use. Although my use is very minimal, I saw this post and wanted to put a good word in for this purchase. These bags are indeed ultralight, warm and are made well. FYI – I also got to try out my new exoskeleton zpack for the first time and LOVED it. I'm going to have to get a second job soon to support my desires for even more of Joe's goods! The solo-plus tent is next :)

[Bob Gross]

I'm halfway convinced that Zpacks sleeping bags are still very new, so there isn't a large customer base yet. Marketing logic suggests that Zpacks should run some promotional sale to get the ball rolling faster.

–B.G.–

[Jacob Blumenfeld]

I have purchased 2 sleeping bags from Joe, one right and another a left zipper with 2oz overfill. Both are the 20 degree bags, and can zip together. I have used them about 7 times since i got them a few months ago, and could not be more pleased. Lowest temp they have seen is the mid 20s under a tarp with 15 mph winds while using summer sleeping pads (neoair one night, zlite another). Was comfortable, but a little chilled on my butt and feet around 5 am, which is not a fault of the bags rating, but due to the sleeping pad. Down is very easy to shift around due to the continuous cuben internal baffles.

[Bob Gross]

So far, the owners/users of these bags seem to have fairly positive reports about them. Those with negative opinions seem to be the ones who simply prefer quilts or hammocks or another brand or something else… sight unseen.

–B.G.–

[Anthony Weston]

I love the zpacks exo.
I'll try and put up a review soon I've been using it for the last 7 or 8 months.
I've tried a fair number of packs.

The weights on the zpacks sleeping bags seem to be incredibly light (amount of fill and loft; seems off) when compared to the Tim Marshall quilts and Katabatic Alsek or Nunatak.

alsek 20 degree quilt has 12.4 oz of fill and 52 inch shoulder girth, 2.75 max loft

revelation 20 degree quilt has 12.4 of fill and 52 inch girth, 2.75 max loft

zpacks 20 degree 5'10" bag has 10.5 oz of fill and 56 inch girth, baffle height 2.25 but I ordered 3 oz of overfill so I have a bag with 13.5 oz of fill that weighs 2 oz less than the competition. The Feathered Friends humingbird is a 20 degree bag with 13.4 oz of fill but it has 5 inches of loft. The baffle height of 2.25 instead of 2.50 which maybe a drawback but I'm not sure if it will limit the loft to 4.5 or not? I'll be using it in 28 degree, dry Sierra weather at worst and I wanted to try the comfort of bag for some trips so I should be fine with this bag.

Anyway, I took the plunge; my contract at work got extended. I ordered a zpacks 20 degree bag with an extra 3 oz of fill for a 19.8 oz bag. I'll let you know what I think when it comes in. The fabric on a bag can make a big difference in warmth. Zpacks is a zipped bag, the others are quilts so less drafts. The amount of room in a bag and the way it's cut also affect the warmth. But in the End Loft maybe the deciding factor on weather this is a 20 degree bag or not.

The zpacks EXO backpack is a 12 oz backpack and it really can carry 30lbs or more comfortably, let you know what I think of the zpacks sleeping bags, as I take it out colder weather.

[Bob Gross]

Lots of people get concerned about sleeping bag length and girth and all that, but I don't. I fit well within the regular-regular dimensions.

I understand how Zpacks sleeping bags shave an ounce here or there off the weight to get a low total. However, since my existing bag is about 23 ounces, there isn't much point in me getting a Zpacks and then overfilling it.

–B.G.–

[USA Duane Hall]

Anthony, that's good to know the EXO can carry 30 lbs. although I am more worried about volume with my bulky stuff.

Duane

[Jacob Blumenfeld]

I find the Zpacks bags to be perfect for me as far as roominess (I am 5ft 6 145lbs). Not too constricting, I can easily sleep on my side in it. Still snug enough to be very efficient at heat retention. I usually use it like a quilt opened up anyways unless it is very cold out.

I do like how the stuff sack he provides with it is a cuben/water proof dry sack. Just requires a few minutes of seam sealing then it is fully waterproof. My bag (5ft10 model + 2 oz overfill) weighs in at 20.50 oz with the cuben dry sack.

I think anybody looking for a hoodless sleeping bag, with the specified dimensions, would be very pleased with Joe's product.

[Anthony Weston]

I expect the sleeping bag from zpacks will be the best sleeping bag I've ever owned, excluding quilts I own. Previously I had a very breathable 2007 Marmot Helium, 1/2 zip that weighed 33 oz.

I came across an interesting article on bpl that has a chart listing 2.2 inches of loft on top of the sleeper equals a 20 degree bag.

http://www.backpackinglight.com/cgi-bin/backpackinglight/bpl_sleeping_bag_position_statement.html

I'm a cold sleeper, a bag that I think is just right, might be too warm for someone else under the same conditions.

However I also think it's fair to ask will I be warmer in this bag or this quilt, if one has more loft than the other.

And like all things in backpacking, it's a tradeoff; maybe it's not as warm but if it's more comfortable than a quilt and I get a better nights sleep than it maybe become my goto bag and I just know to wear my down vest to bed when needed.
And I agree Joe makes excellent products.

[Dan @ Durston Gear]

As per the research of R. Nisley, we've learned in the past year or two that the warmth of a down sleeping bag isn't entirely correlated with loft. Nisley has shown down can be compressed moderately (ie. 2-3x) and not really lose it's effectiveness. Down compressed 2x might only have half the loft, but since it's now a higher density, it's nearly twice as warm per inch of loft, so the total warmth is hardly affected. This holds true until a surprisingly high amount of compression, so even down compressed 3-4 times is still going to have most of it's uncompressed insulating value. It's true that it's most efficient to have down not compressed at all, but it's almost as good to have it moderately compressed.

So one sleeping bag with 3" of loft could be much warmer than another sleeping bag with 3" of loft, if the one sleeping bag has a lot more down packed in there. BPL's position statement on loft and warmth is quite outdated, and really not that useful for determining warmth

Ultimately warmth almost entirely comes down to how much down is in the bag, divided by the size of the bag. While it's not 100% perfect, simply looking at the amount and quality of down in the bag is the best way to make a quick judgement on it's warmth.

Before you can really compare how much down is in two sleeping bags/quilts, you need to consider how big the bag is. Zpacks sleeping bags fall in between quilts and normal bags, because they have a little more girth than a normal quilt, but still no hood like a sleeping bag. So to be just as warm as a normal quilt, they need a little more down (since it's spread over more area).

With that in mind, we can observe that Zpacks puts 7.3oz of high quality down in their regular sized 30F bag, while Katabatic Gear puts 9.5oz in their 30F Palisade quilt. Considering that the Zpacks bag spreads that down over more area (56" wide vs. 52" wide for the Palisade), we can conclude that the Katabatic 30F quilt is easily warmer than the Zpacks 30F bag.

If you expand these comparisons to include other quilts and brands, you'll see the Zpacks bags typically have less down than other options. The GoLite 3-Season quilt uses 12.5oz of down to get its 20F rating and Katabatic puts 12.4oz in it's 22F rated Alsek quilt, yet Zpacks puts only 10.5oz of down in their 20F 'bag' even though it divides that down over more surface area than the other two options.

I'm not saying this to bash Zpacks. I love their stuff and I think their quality and materials is awesome. I just mention in the hope that people will largely ignore temperature ratings and instead focus on how much down they are getting.

[Dustin Short]

Dan, this is only a partially correct. Loft is still the deciding factor in warmth.

The insulation properties of down do indeed increase as you compress it (up to the roughly 2.5X point) but this is still on an insulation/thickness measurement. Unfortunately the clo/oz does not scale appropriately. Richard was absolutely correct in his conclusions except he got caught up in maximizing numbers and forgot what the main objective is…increasing performance on a per weight basis. Perfectly reasonable distraction when you get absorbed by a data set. I'd have to look up all the data again (which won't happen, I spent too much time the first time I got involved in the debate) but I think the max-min intersection of clo/inch and clo/oz was pretty dang close to fully lofted.

That said, there are benefits to overfilling such as preventing the down from shifting and potentially stabilizing loft collapse due to moisture gains. What's the magic number on these issues is beyond me since no one's done the research and I don't have the time, desire, or funds to experiment myself. But the standard 30-50% should be a decent overengineering rule of thumb that doesn't degrade performance too much from optimal.

[Bob Gross]

One thing to consider is what happens when a down sleeping bag gets compressed, and then you introduce a lot of moisture (hopefully, unintentionally). When the down particles are compressed, the moisture will migrate through the particles quicker, and that leads to a big mess (the cold wet sponge). When the down particles are completely uncompressed, the moisture will not migrate so quickly, and there is still more air in between. Now, most of us do not plan on our sleeping bag getting that wet. But, in a worst-case scenario, I would opt for the light and airy uncompressed down. Most of us do plan on compressing and uncompressing our sleeping bag periodically, because that is normal use.

I have one down bag with a Goretex-like shell. It gets really interesting with moisture.

–B.G.–

[Dan @ Durston Gear]

"Loft is still the deciding factor in warmth…..Richard was absolutely correct in his conclusions except he got caught up in maximizing numbers and forgot what the main objective is…increasing performance on a per weight basis…I think the max-min intersection of clo/inch and clo/oz was pretty dang close to fully lofted."

It's true that it's most efficient to have the down completely uncompressed, but the main new thing Nisley showed it's still ~98% as efficient if it's way over stuffed. So the principal take-away point for the non-science geeks is there's not much point in worrying about compression/loft/density/overstuffing. The average person shouldn't lose sight of the main factor (how much down there is) and get distracted by less correlated measures of warmth like loft.

Bottom line is that the amount of loft tells you a lot less about how warm the bag is, then the amount of down.

[Tim Zen]

d

[Bob Gross]

"I am not sure about having the zipper on your back."

That's why I would opt for the custom side zipper with draft tube.

"It does not seem to have a hood like my Summerlite."

It doesn't have any hood.

–B.G.–

[Richard Nisley]

Dustin,

You are correct that the complete sleeping bag/quilt's clo/total system oz is what an UL backpacker should be concerned with… it stays the same over the linear portion of the areal density curve.

I first explained this in my post titled and dated Re: Re: question for Richard… on 10/13/2008 21:13:15 MDT; see http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=16189&startat=20

[Tim Zen]

d

[Rusty Beaver]

For those who have a Zpacks bag, a few questions on the neck closure. Is it a bungee or standard flat nylon? I assume the cordlock is on the top, by the chin. Is that correct?

Also, what is the foot box like? From the pics on Zpack's site, the bag looks flat all the way through, from neck to feet.

As a side note, I'm thinking one of these bags with the zipper on center top, with a draft tube, would suit me well.

Would love to see some pics of people in these bags.

[Michael Cheifetz]

Rusty
If top center zip is what you are after take a look at the nunatak alpinist as well (i have a custom one with 4oz overfill and cinch cord footbox)

[Rusty Beaver]

Thanks, Michael. I have leered at that bag before….and it looks really, really good. However, my small pocketbook can't justify Nunatak's prices. I'm also thinking that combining a hoodless bag with separate hood might work better for my sleeping habits. But yeah, there's no doubt about it. The Alpinist is one sexy beast!

[Richard Lyon]

Bob,

Would you be interested in my Valandre Mirage – (Quote from Gear Swap) "Size Long, silver Pertex Quantumc fabric with left quarter-zip. Rated to 25 F. No storage bag or stuff sack. Bought on this forum, moderate use, good condition. 23.9 oz $200 plus shipping"

I can send pictures if you like.

Richard

[Author]

Posts