Touring - A question on fleece liner bags

Do the inexpensive fleece liner bags (that are often sold as summer bags) get you another 10 degrees of warmth if used within your standard down or synthetic bag? Just wonder if it would be worth carrying one since we're going to be riding in an area that has some significant variability in temps at that time of year. Thanks for your input.

10 degress more? I doubt it. I'd wear thicker thermal undies and warmer socks + a hat and then maybe a down jacket/vest inside you bag for a better warmth bang for your buck than one of those fleece bags.

I think of my liner primarily as a way of keeping my sleeping bag cleaner. The liner can be washed easily, the bag, alas, not. I haven't noticed it keeping me any warmer.

Depends on the fleece thickness. They do make a difference-I've used them a couple times when car camping. They are bulky, but cheap, and there are sometimes only so many layers you can put on before they start restricting blood flow. Not a great solution, but not terrible if you want to avoid purchasing a whole 'nuther lower-rated bag.

I have one, and I think it would add ~10F. I've used mine alone as a summer bag, and it's nowhere near as warm as the lightest 3-season sleeping bag. Fleece is too porous, too much exchange with colder outside air.

A fleece sack is not that light - the same weight in clothing will accomplish the same thing, while being more versatile (uses besides sleeping only). Vik's advice on hat and down jacket would be my choice too. I'd throw in a fleece zip turtle neck pullover too - all those would weigh less than the usual 200 wt polarfleece liner bag.

I carry a fleece pullover & pants which I sleep in for added warmth. Of course they serve a dual purpose as wearing apparel.

people have used vapor barrier liners , to add some lower temperature capabilities
the theory is by not letting perspiratuin out the sweat doent cool you
or cause the bag to get damp from sweat and lose loft
and so not be as warm as a dry bag's insulation.
takes up virtually no space .. for the liner.

Other than that , wear more clothes in the bag seem practical

i have compound knit sweat pants on .. fleecy poly on the inside, slick nylon on the outside .
probably good PJ's in that situation.

Seems like a lot of weight to carry and without the versatility you'd get from carrying some extra clothes such as fleece pants or a sweater - things you could use both while sleeping and other times.

For extending the temperature range of my sleeping bag I do sometimes take a vapor barrier liner (VBL) - a very lightweight (a couple ounces) waterproof liner. Keeps you from losing heat through the evaporation of water from your skin during the night. But I only do this when it's below freezing - at warmer temperatures it would turn the bag into a sauna. Also has the benefit of keeping the down insulation completely dry so it works better and I find that I'm not as thirsty in the morning. Without the VBL my bag is comfortable down to about 30F and with it I've been comfortable to the low teens and slept fairly well down to 0F.

I've used a Sea to Summit liner and I would say it added 10 degrees. For 8 ounces about the size of a grapefruit I thought it was worth it. About $54 from REI.

Do the inexpensive fleece liner bags (that are often sold as summer bags) get you another 10 degrees of warmth if used within your standard down or synthetic bag? Just wonder if it would be worth carrying one since we're going to be riding in an area that has some significant variability in temps at that time of year. Thanks for your input.

Will a liner make a +10 bag into an effective 0 degree bag or a zero into a -10. Pretty close in my experience. I don't have a scale handy but I would be surprised if packing extra clothes to sleep in will weigh less than the fleece liners I've seen. Wearing extra clothes in the bag is a double edged sword. Too many clothes reduce the dry air in the sleeping bad and if you sweat you are seriously working against the bag. Long underwear and a toque should be enough if you have the right sleeping bag combinations until you find yourself sleeping in an igloo.

Hand in hand with the sleeping bag is a ground mat or air mattress. Having the right one for the conditions you'll be in will make the difference between being warm and being cold and stiff.

+1 on cleaner. A cleaner sleeping bag is a warmer sleeping bag.

Thanks for the responses. This is one that I was looking at, says adds 10 degrees at 15 oz.

http://www.rei.com/product/739503

I don't have a scale handy but I would be surprised if packing extra clothes to sleep in will weigh less than the fleece liners I've seen. Wearing extra clothes in the bag is a double edged sword. Too many clothes reduce the dry air in the sleeping bad and if you sweat you are seriously working against the bag. Long underwear and a toque should be enough if you have the right sleeping bag combinations until you find yourself sleeping in an igloo.

No one claimed that carrying some fleece clothing would be much different in weight from the fleece liner - but the clothes can also help keep you warm in the evening before you get into the sleeping bag and in the morning (when it's usually coldest) as you start to break camp. So it's good to have this clothing along anyway in cold weather and you may as well use it at night. Both the clothing and the liner will occupy space in the sleeping bag and in either case you may start to sweat if it makes you too warm - in that case you shouldn't use either supplement in the bag. OTOH, if you go with a vapor barrier liner then it's advisable to wear no or only minimal clothing inside the VBL. Any extra clothes (or fleece liner) can still be used but should be kept as a layer between the VBL and the sleeping bag. That keeps all the insulating material completely dry and effective.

BTW, an igloo is generally quite a mild temperature inside and shouldn't require any extra insulation if you have a reasonable sleeping bag. Igloos block the wind very effectively and the snow is a good insulator so the temperature inside is much warmer than it would be in a tent.