I went for a mini tour this weekend, 3 days in upstate new york. It was fairly chilly at night, probably in the low fifties. I was using a Mountain Hardware 20 degree synthetic bag, and I was a bit hot. I didn't like how I would sort of stick to the nylon of the bag, or the nylon of the pad.

I'm going on an 8 month trip through South America and I was thinking of picking up a bag liner. I figure in the hot weather I can use the liner only, and when I'm up in the andes I can combine the two bags for super cold weather.

What have peoples experiences been with bag liners, and in what temperature ranges have they been useful? Does the layering idea work?

Also, I'm using a neoair pad underneath.

I've used the Sea 2 Summit Thermolite Liner (https://www.seatosummit.com/products/display/24) with my Ultralamina 32 in down to -10C (~15F) and it worked OK. This was of course well beyond the limitations of the bag, or even the bag and liner combined. I think the liners should work fine by themselves, and as long as they're used within a 10 to 15F range of your bag, should do fine there as well.

Layering does in fact work, and many bring liners just because they don't like the feeling of nylon.

I sewed an old cotton bedsheet into a bag liner for inside my 20 degree sleeping quilt. I've stayed warm on 10 degree nights. I use it on it's own when the night temps are above 60. The layering effect is real, typically ~5 degrees more of warmth, and less chance of coming across a pocket of cold air inside your bag while shifting around in the night.

I enjoy the feel of cotton more than nylon. A liner, whether silk or cotton is much easier to wash than a sleeping bag. The liner kept my sleeping quilt pretty clean over my last 6 month tour. This meant that my quilt retained it's loft better over that time. Less dirt, less washing means a longer lifespan for my sleeping quilt.

I don't use a tent so I sized my cotton liner so I could pull it up over my head. This increased warmth, kept the bugs out and my breath passed through easily.

I've used a liner with by sleeping bags for a long time. I use a Moonstone liner that has a mylar reflective center and nylon cover, it can extend the comfort range by 10 degrees, at least. It's very light and compact, so takes very little space for packing. It is part of my regular gear list, almost never go camping without it.

I also tried the Sea to Summit Thermolite Liner this year and was impressed with the extra warmth. I was able to move well in the sleeping bag without getting bound up like I have with cotton before. I think it is well worth the extra 8 oz. and grapefruit size space it takes up.

I make mine out of poly flannel.Nice and soft,quick dry.

Thanks for the feedback. I've been looking at those Sea to Summit bags.

The manufacturers usually claim the liner adds 10 degrees of warmth. I was thinking of moving from a 15 degree bag with no liner to a 30 degree bag with a liner. It seems more flexible to me, and obviously the 30 degree bag would be lighter.

I sleep cold I have to add about 10 degrees to a bag's rating to get real world results. I primarily use an older Cat's Meow flannel lined bag with a silk liner and I am good down to around the 25*f mark. FWIW the Cat's Meow is rated to 20.

Aaron

I bought a silk sleeping bag liner in Vietnam for $4. I don't know if it adds much warmth because I have not used it in cold weather. I don't really like the feeling of silk, though this stuff is probably pretty cheap! I am going to switch to cotton or flannel.

1- i use silk liner too, +/- $15 usd (eBay), and can add about 10 deg F comfort
2- i always carry a "space blanket". it has worked very well, but holds moisture with heat
3- i have a sleeping bag outer shell making 3 season bag to 4 season (different topic :-)

the silk liner is good during warm summer rides too, used on top of sleep-bag, and an easy wash!

stay comfortable!
t

I use a silk liner because it's easier to wash than a down sleeping bag and it feels good. It supposedly will extend the comfort range of the bag to a somewhat lower temperature, but I've never tried.

I actually have a coolmax travel blanket kicking around that is pretty much the same thing. I think I am going to try that for an overnighter in a couple of weeks and see how it goes.

After nearly 3 years of full-time touring through temperature extremes, I think I've finally figured out the perfect combination. I used to have a very warm sleeping bag - I loved it in the cold, but sweated way too much in the heat. Then I got a summer bag and was fine in moderate temps, but still sweated when it was hot and froze when it was cold. now - I've got it figured out! I still have my lightweight summer bag, but needed more. I went down to the fabric store and bought a couple of meters of lightweight fleece material and sewed it into a sleeping bag. I used the sleeping bag/fleece bag combo going over a 15,000 foot pass in southern Peru in the middle of winter (temps down to around 5 or 10 degrees) and was fine! I also picked up a small alpaca shawl and wrap that around my head and neck on cold nights - toasty! What I really like about this set up is that the fleece is thick enough to use as a light blanket - a sheet doesn't do it for me unless it's really, really hot. I can use the fleece in grungy hotels rather than using their blankets, and can use it in my tent most nights. If I get cold with just the fleece, I can generally just throw my sleeping bag over it like a blanket. And the fleece is much easier to wash than my sleeping bag. So - for what it's worth, that's what I suggest for South America. the combination of a summer sleeping bag and the lightweight fleece won't weigh any more than a winter bag and won't take up any more space - but it's infintely more flexible!! Here in S. America you'll go through lots of temperature extremes, so the flexibility is wonderful.

Argghhhh!! What happened to my paragraphs in that last post? It wasn't supposed to be one great big run-on paragraph.

Thanks Nancy, that's really helpful advice. I never planned for a tour with the temperature extremes that I am going to see in South America, so it's been a challenge.

By summer bag are you talking about a 30 degree bag, or something even lighter?

I'm not sure what rating my bag has - I picked it up in the bargain basement of an outdoor shop up in Canada. I suspect it's probably something like 30 degrees or some such thing.

Cool. I'm going to try out a liner with the 20 degree bag I have now and see how it goes. I might switch to a lighter bag if it feels like overkill.