Sunday, June 28, 2015

All of Cesar's Ultralight Sleep Systems: From 20C to -16C and Everything in Between

Ye Olde Gear Closet

Seeing as I recently finished up my complete breakdown of all of my Ultralight shelters, and I'm also on summer vacation, I figured I should strike while the iron is hot and also write up another breakdown I've wanted to do for a while.  Regular readers will notice a pattern by now of me putting the finishing touches on all of my Ultralight backpacking gear wants/needs for year round use and under nearly all circumstances relevant to me.  My sleep systems have been no different.  So now that I've explored my backpacks and shelters, here is the last of the "Big 3" of backpacking.

This report is more straight forward, as there is pretty much a single factor that I use to determine what sleeping system I bring with me on a given trip: lowest temperatures predicted in weather forecasts.  Of course I take these forecasts with a grain of salt, because in addition to at times being inaccurate or there being a change in weather, temperatures way out in the woods can vary greatly depending on where one sets up camp.  I've written about the dreaded cold sink and cold snap plenty of times before (like here for example), and of course experienced outdoors enthusiasts will understand the importance of location when it comes to having a more comfortable/warmer campsite.  And also keep in mind that my temperature categorization is based on my own subjective comfort levels and what keeps me warm and snug.

I won't be doing any videos to accompany this report, because I think pictures suffice for one to see how a sleep system is like, and how one packs sleep systems can vary depending on several factors.  I personally like to pack my sleeping bags in slightly larger stuff sacks to help preserve their loft and take care of them, for example.  Others like to put their sleeping bags/quilts into compression sacks to get them as small as possible, yet others still don't use any stuff sacks at all for their bags and just stuff them into the bottom of their packs.  Sometimes I use my sleeping pads as the back "frame" of my frameless backpacks, other times I will roll them up, and I never use any stuff sacks for them.  So I won't include any stuff sack weights, though I tend to use silnylon stuff sacks for my sleeping bags that I bought from Zpacks several years ago when they still sold silnylon stuff sacks.

Also keep in mind that in addition to always taking with me a small foam pad for use as a sit/kneel/all around pad, where I live and do the grand majority of my backpacking trips also provides me with a wealth of natural materials to take advantage of should I need to.  However I rarely need to take advantage of these natural materials, but if there is ever an extreme cold sink/sap, I could of course make myself a thick sleeping nest of pine boughs, moss, grass, etc.  And I could also get a fire going.  But these sleep systems are intended to be used without needing to resort to these woodcrafty techniques, yet one factor to take into consideration that won't be covered here is clothing.

For each given trip I always make sure to have an effective clothing worn and packed clothing set.  Getting into this would further complicate things, and if you're reading this you probably already understand good layering techniques and such.  If not, just know that I can sleep in my base layers, down vest or jacket, wind jacket, etc.  I usually will take off my hiking pants and shirt at night at let them air out overnight and change into a base layer to sleep in, and wear whatever layers I think I will need for the night.  There is one exception to clothing that I will discuss in this review, which only gets used to sleep in (and briefly around camp) in very cold temperatures, and that will be seen shortly.

So let us begin from warmest conditions to coldest from 20C / 68F to -16C / 3F.  Anything warmer than a low of 20C / 68F is very rare here in Scandinavia, but I'd just take my least warm system if that were the case.  Anything colder than -16C / 3F and I am staying home with a mug of hot chocolate and a good book, though I feel quite confident that my warmest system (plus all my clothing) would keep me warm enough (though perhaps a bit chilled, but I'd survive) down to at least -20C / -4F in the event of a cold sap/sink.

20 to 17C (68 to 63F)

  • MYOG silk/Apex 2.5/Argon 67 sleeping bag (El Saco Verde), 285g / 10.1oz
  • Generic thin foam mat, 100g / 3.5oz
  • Total: 385g / 13.6oz

Not much to say about this set up.  Pretty simple.  Not the most comfortable sleeping mat to use say inside of a trail shelter, but sleeping on soft moss in the woods it works great.  In fact, I've slept without any sleeping pad at all on many occasions in the past in warmer weather (like on this trip, for example), and so long as you pick a good spot, it's can actually be quite comfy.

16 to 12C (61 to 54F)

  • El Saco Verde, 285g / 10.1oz
  • Nemo Zor (size short), 270g / 9.5oz
  • Total: 555g / 19.6g

Again, not much to give commentary on here.  Will add layers if needed, like a wind shirt over my base layer top, down vest, sleep socks, etc.

11 to 6C (52 to 43F)

  • Zpacks 40 sleeping bag (wide/long), 415g / 14.6oz
  • Nemo Zor (size short), 270g / 9.5oz
  • Total: 685g / 24.2oz

You can read more about my two Zpacks sleeping bags here.  Otherwise, not much to add here either.  Here clothing is more of a factor as temps go down, where I usually will wear a long sleeve synthetic shirt over my base layers, then down vest and/or wind shirt as needed.

5 to 2C (41 to 36F)

  • Zpacks 40 sleeping bag, 415g / 14.6oz
  • Thermarest Neoair Xlite (size regular), 350g / 12.3oz
  • Total: 765g / 27oz

I've owned and used an Xlite for a few years now and love it.  However recently I had it replaced because the lamination was coming off on the inside, and was sent a new pad because this is covered under the limited warranty.  I was happy to find that the new pad was also slightly lighter than my old one.  Sleep socks, gloves, beanie hat, and the hood of my wind shirt get good use along with the rest of my normal layers.

1 to -3C (34 to 27F)

  • Zpacks 40 bag, 415g / 14.6oz
  • SOL Escape Lite bivy, 148g / 5.2oz
  • Xlite, 350g / 12.3oz
  • Total: 913g / 32.2oz

The SOL Escape Lite bivy I bought recently on a whim while I was killing some time at a camping/outdoors store while waiting for a bus.  It was relatively cheap and pretty light, so I thought I would put it to the test in a head-to-head comparison with El Saco Verde (see:above).  If you've read up on my MYOG summer bag, you will know that I had intended to use it as an overbag for my Zpacks 40 bag for more warmth and to keep the down drier, and I did use it to that end.  I tested out my creation on one section hike vs. the Escape Lite bivy on another section hike, both of which had similar temperatures.  To my surprise, the SOL bivy added about the same amount of warmth as my MYOG bag, plus much roomier and of course lighter.  

Yet I wouldn't use the SOL bivy on its own as a sleeping bag, but that's just a personal preference issue I have with the fabric.  My Saco Verde's interior is silk, so it's very comfy, plus more durable and easier to clean than the SOL bivy.  Sure, it's a 135g / 4.8oz difference between the two, but if it's warm enough to use El Saco Verde, I am already at or close to SUL base weights, so call it a SUL luxury I suppose.  However as a great way to extend the warmth of my sleeping bags and also keep them drier, plus block drafts/wind, I think this is a great addition to my gear closet.

Clothing gets more involved at these temps.  My base layers switch from silk to merino wool, and an extra layer of clothing worn is added, along with warmer hat, gloves, etc.

-4 to -7C (25 to 19F)

  • Zpacks 20 sleeping bag (wide/x-long), 610g / 21.5oz
  • Thermarest Neoair Xtherm (size regular), 465g / 16.4oz
  • Total: 1075g / 37.9oz

Now things are really starting to get frosty.  My down vest gets replaced by my down jacket, and naturally layers added and warmer options are also replaced with clothing accessories.  If you've been paying attention, you can probably guess what comes next...

-8 to -12C (18 to 10F)

  • Zpacks 20 bag, 610g / 21.5oz
  • Xtherm, 465g / 16.4oz
  • SOL bivy, 148g / 5.2oz
  • Total: 1223g / 43.1oz

There is enough space in the SOL bivy for my 20 bag to fit just fine, so next winter I will get to test out this combination.  If it works as well as it did with my other sleeping bag, I'm confident it will work well with this one too.  And of course at these temps, continue to add warmer layers and such.  Next stop is the lower limit of my sleeping systems.

-13 to -16C (9 to 3F)

  • Zpacks 20 bag, 610g / 21.5oz
  • Xtherm, 465g / 16.4oz
  • SOL bivy, 148g / 5.2oz
  • Generic thin foam mat, 100g / 3.5oz
  • Cuben down pants, 145g / 5.1oz
  • Total: 1468g / 51.8oz

Now we're talking serious cold.  If it gets this cold next winter (which it didn't last winter), this is the set up I plan on taking.  I am thinking that I might put the foam mat inside of the SOL bivy if there is room, because I think it would offer more warmth/insulation than having it under or on top of my pad.  If/when I try this out, I will give an update here, as I normally do with my long-term gear use.  Otherwise I can put it on top or under the air pad, and the addition of my down pants along with the rest of my warmest clothing complete this sleep system.  If it was right at, or if I was worried that it would go slightly below -16C / 3F, then I could also take El Saco Verde and use it as a sleeping bag liner.  I don't think I will have to do that very often, though.

That wraps up my final complete breakdown for my Ultralight big 3 categories of gear.  Should anything change, as well as any reflections on further testing in the field I think are important, I will be sure to write additional updates in the future.

As always the same old disclaimer: still not sponsored and still don't get any gear for free.  And actually I've turned down a few offers, now that my blog seems to be picking up some steam.  Thanks to all my readers, especially any regulars and those of you that have shared my posts and videos and such.  And as usual, please feel free to ask questions or give feedback in the comment section below, especially those of you that have experience with year round backpacking and have dialed in sleep systems.

Enjoy the summer while it lasts, for all of us in the northern hemisphere!

Update 07/07/2015: Fixed up some minor formatting and typos, added some minor details on coldest sleep system.

Update 19/10/2015: Fixed up some more formatting issues I missed last time, re-worded a few sentences for cohesion. 


  1. The SOL Bivvy looks like a brilliant idea. I'm going to try it this winter here in New Orleans. We have rather mild winters this far south but a 40F quilt isn't quite enough traveling just a little north.

    1. Yeah, I have really been happy with the results of using my Zpacks 40 with the SOL. Saves me having to buy a 30 bag, or even a 10 bag if it pairs well with my Zpacks 20 bag (which I think it will). Just this past weekend (check out my latest post for trip report) I went out and used my 40 bag with the SOL bivy and it worked great. I was toasty warm--I mean, like not a chill at all the whole night--and it was around 2C/35F outside, plus I slept in a trail shelter right on the banks of the lake (so high humidity too). No condensation on the inside on the sleeping bag or bivy either.

      Hope this combo can work for you down south. I used to live in Alabama and would go into Louisiana often. Beautiful nature! I loved the lakes and swamps all covered in green, and all the vines and such all over.

      Let me know how it works out for you, and happy trails!

    2. My 3 season bag is a factory overfilled Western mountaineering down bag good to 20 F. The pad is a Thermarest Prolite.

      My winter bag is an LL Bean -20 down bag with Down Tek DWR. The pad is a Thermarest Trail Pro. If absurdly cold (-30 F. or lower) I'll add a Thermarest Ridgeline closed cell foam pad.

  2. Hi Cesar. Is the minimalist Escape Bivy you use made out of the same material as the previous ~8 oz. Escape Bivy with the Zipper?

    I recently used a ~50 degree down envelope bag (sideways, quilt-style) inside my Escape Bivy on a night that went down to around 40 degrees. I woke up an hour or two after first falling asleep, and there was a fair amount of condensation between my sleeping bag and the Bivy.

    You mention that this hasn't been an issue for you? I'm just curious what I'm doing wrong. Might be a little too late at this point because I cut the top half of my Bivy completely off, so it would only cover my legs. I'm hoping that will be enough to cut condensation, and give that extra boost of warmth to my lower half that I was looking for (it's only about 2.5 oz. now, so this might have been a good decision regardless).

    1. Howdy! I am not sure if they are exactly the same material, but they have to be either the same or quite similar. On the package of the bivy I remember that it said that the Escape Lite was two "check marks" vs. three for the regular escape. Could be marketing to get people more concerned about durability to buy the regular, could be that the Lite is slightly thinner--not sure.

      But yeah, I never had any issues with condensation. I plan on giving updates on this combo as I get more good use out of it. If you already cut yours up, I am guessing that it will solve the issue of condensation.

      Happy trails to you.

  3. BTW, for winter I recommend a "nose-covering" balaclava or face mask and balaclava. A cold nose makes one unconsciously put their face into the bag, making it damp.

    1. Thanks for the feedback. Yeah a balaclava or a buff is a great addition to winter kit. I have both, but usually the merino wool buff is enough. All my sleeping bags are hoodless, so I don't have the problem of putting my face in my bag. One of the pros of going with a quilt or hoodless bag. Happy trails!