Lightest 20F Synthetic Bag?

"Well… apparently you haven't taken your research to REI… or even read the previous posts in this thread. From earlier in this thread: "REI sells their synthetic Lumen bag with advertised weight of 2 lb 8oz (40oz) for regular length."

Nope, just ignored it actually. If you do your research properly, you'd try to note not only manufacturer specifications but also users' reviews, and here Lumen may appear to be overweight to 2lb 10oz. Which if true, would bring it in line with Hyperlamina.

Which doesn't mean the latter is not (or could not be) underrated – see earlier post on manufacturing process using synthetic fill. Yet coupled with the fact that Lumen doesn't seem to be ever recommended, I chose to stay clear in light of alternatives available. (Not a gear snob rather unwillingness to throw money away for no good reason!)

Monkey…
I see you like to quibble and argue:

"If you do your research properly, you'd try to note not only manufacturer specifications but also users' reviews, and here Lumen may appear to be overweight to 2lb 10oz."

Fact is you missed a viable option but stated results as though they were complete. And if YOU did you 'research' properly you would note that "reviews" by consumers are suspect at best. And the bags that you recommended could well be 2 0z heavier that specs state… in fact, it is quite common.

billy

^ Whatever works for you sir!

If you are serious about backpacking and weight you need to learn this:

A good quality DOWN not SYN. sleeping bag / quilt is the single most important item you will ever buy.

Down is much warmer, lasts a lifetime without loosing warmth, lighter weight, and packs smaller. If your worried about getting it wet get a Event dry sack for a few extra ounces.

I agree with Michael.
"A good quality DOWN not SYN. sleeping bag / quilt is the single most important item you will ever buy.

Down is much warmer, lasts a lifetime without loosing warmth, lighter weight, and packs smaller. If your worried about getting it wet get a Event dry sack for a few extra ounces."

Where does good quality start? Well, around 800 fill (US measurement, in EU it would be 700 fill.) Well stitched, good baffles & evenly filled, good zipper & guard.

Warmer? Well, "warmer" for the weight. Really, it is only a better insulator.

It compresses a heck of a lot smaller, maybe 1/3 to 1/4 the size of an equivalent synthetic.

Finally, it lasts at least 20 years. This is with proper maintenance. Never wash it with regular detergent. Use a down soap. Do not store them stuffed. Best is hung. Second best is in a large stuff sack usually supplied with the bag. Do not store them damp/wet or compressed.

Cost? Well, Down is the cheapest option. Over the 20 year life time, you take the initial $500 devided by 20 years and you get around $40/year. Synthetics last about 2 years. So you need 10 bags to maintain the 20F rating or around $1000. This is around $100 per year.

Weight? A typical down 20F bag is around 2pounds. A typical 20F synthetic is 3.5 pounds. Or down weighs about 60% of the synthetic for similar "warmth."

A sleeping bag will be your single most expensive purchase, on average. Yes, Cuben shelters can cost more, but these are more geared to SUL than UL or Light weight packers. Going with a quilt can save more, but you said you didn't want a quilt. Do it once and do it correctly. For the next 20 years you will save weight, be warmer, and be cheaper.

The only down side is getting your bag wet. Down handles being damp, OK. Wet, it looses a lot of insulating value. Synthetics are better if you sleep in the rain with no cover or in a mud puddle.

"Finally, it lasts at least 20 years. This is with proper maintenance."

"Synthetics last about 2 years."

What is the source of this data? I'm curious, as we decided to go with synthetic partly because of wet climate, but also reading reviews that suggest that down performance is not very good long-term. For example reading Christine:

"Over the years I expanded and bought more and more WM bags for warmer and colder conditions still believing in the UL mantra that down is always better because it is lighter than synthetic. But once I started hiking outside the relatively dry Western US I quickly learned about the disadvantages of down. In damp conditions down clumps and loses its warming abilities. Long term use adds to the problem as body oils also make the feathers clump. Despite washing the bags with down soap the problem persisted. I found down to become very unreliable. Any foggy night or wet tent wall would deteriorate its warming abilities and I never knew when I would be able to dry the bag again. It took me a long time but after several years of frustration with down I started using synthetic. The big downside of synthetic is its higher weight. But I could compensate it by changing from a full sleeping bag to a quilt. This was a big step and I was very nervous how my new setup would work out. I first tried it on a hike across the UK where the climate is so damp that I knew I would almost certainly encounter problems with down. The new synthetic quilt worked out so well that I have never used a down bag again. Synthetic is so much more reliable than down. No matter how much you abuse it, it will still keep you warm. Touching wet tent walls, condensating breath and foggy nights were not a problem any more. Even if I could not air the quilt for several days or even a couple of weeks, it still kept me warm. I also could not see that the synthetic insulation was deteriorating from being compressed every day. And now I honestly wonder why synthetic is not more popular."

And in particular on durability of down vs synthetic:

"I have been using Western Mountaineering sleeping bags for the first half of my outdoor career and depending on the climate I was alternating between the Summerlite, the Ultralite, the Versalite and the Puma. Generally speaking the bags are high quality and very durable. … After about half a year of constant use the down in the bag will start clumping and thus reduce the warming capacity of the bag. Washing will restore part of the loft, but still it is my experience that no matter how and how often you wash the bags, after one year of constant use they will have reduced loft so much that the original temperature rating will not be achieved any more. After 2 years of constant use the down has so much deteriorated that the bag is practically useless and even washing will not restore it any more..
After a lot of problems with clumping down due to extended use and/or humid conditions I have now changed to synthetic quilts. I am using a BPL 240 quilt for 3 seasons and a Enlightened Prodigy 20 for colder temperatures. I have used both quilts for around 300 nights without any significant deterioration of loft or any other substantial defects. I realise that about every outdoor book and forum will tell you differently, but in my personal experience synthetic is much more durable than down. "

Synthetics are better if you sleep in the rain with no cover or in a mud puddle.

For whatever reasons, Billy wants a 20F synthetic bag. He's researched it well, knows himself and his needs and is no doubt familiar with the weather conditions in the area where he plans to use it. He's been on BPL plenty long enough to have read and participated in the back-and-forth debates numerous times.

I love my UL down gear (EE quilt, Montbell UL jackets, etc) but synthetics do have their place.

Last fall I was down in WV for a trip (Seneca Creek/Spruce Knob) which featured the most rain I have seen on a trip in quite a few years. It was also the maiden trip for my Duomid.

It rained a few inches over 3 days and the relative humidity was above 90% for most of the time. Even with plenty of ventilation there was a bunch of condensation inside the mid, and when raindrops fell on the outside of the tent they created a constant little mist inside. Everything inside the tent got damp.

I was extremely glad to have been using my EE Prodigy synthetic in that instance (and having a fleece jacket as well!). I'm convinced that taking along a down quilt or bag would have been a disaster in that super-saturated environment.

Well, I have no hard data but living in a damp climate and using my down bag in it for years without any problem, I know from experience that my down bag just works in those conditions (and sometimes even worse). I still have a synthetic bag (a Cat's Meow with Polarguard 3D) and while the original rating was 20 or even 15°F, it is now more likely ± 50°F. The down bag was originaly rated ± 32°F and based on my experience it still has that rating.

I don't know. I have never had a bag for more than 22 years, so I cannot say. But, I know my down bags are in good shape and easily hit their rated temp after 16 years. There is little to no degradation of the down. I use my bag about 60nights per year and usually dry them when I get back, if not wash them…usually after two weeks of use. I have been using them the same way since they were new. Usually with a set of long johns, maybe a down jacket if it is below 32.

I used to buy new synthetic bags every two years with the family. My wife insisted that we buy zip-together bags. They would loose loft and start getting flat despite always storing them hung up. 'Corse, one time we brought in some brandy and I ended up sleeping in a lake, I froze…another story… Anyway, below 40F, my feet would always get cold.

No research, just more than 40 years of camping experience…

I have a Mountain Hardware Ultralamina 15. I'm not sure how old it is, but I would guess about 5 years. I bought it used, but it was lightly used and maybe a year old at the time. Despite the "15" in the name, mine is EN rated at 19 degrees, so it's a 20 degree bag to me.

Now, after a few years of use (certainly less than 100 nights, but a better guess is 50-60 nights) it has lost a lot of loft in the foot area. The insulation there feels denser and less fluffy than it should be, and there is space between the insulation and the shell fabric. Maybe it de-ultra-laminated?

I have not washed it yet (ever), but it's not visibly dirty or smelly. I usually use it with a liner or clean clothes, or sometimes dirty clothes. I plan to wash it soon, but I don't expect it to make a full recovery.

Now when I use it I'm cold in 40 degree weather unless I wear a down jacket and socks inside. I bought a Marmot Hydrogen (30 degree) a couple years ago, and even then the Hydrogen was slightly warmer and more lofty than the Ultralamina.

I need to replace it with a down bag before this fall/winter.