I currently have a Marmot 15F Helium and Marmot 40F Arete sleeping bag. What I've experienced in my 3 season treks so far is that I have roasted in the 15F bag and been too nervous on just taking the 40F bag fearing lower temps.

I just bought the Marmot 30F Hydrogen as a go between, and I am in the process of developing a sleep system that I could use for a wide range of temps.

My setup would be:
30F Hydrogen
Neo Air full length pad
Hexamid tent

Clothing:
short sleeve shirt
long sleeve shirt
Montbell down jacket (12 oz jacket no hood)
Capilene 2 bottoms
REI convertible pants
Frogg Togg tops and bottoms
Mountain hardware powerstretch gloves and balaclava
Goosefeet down socks over my normal running socks

It seems like with all this clothing and protection, I can extend the 30F bag down to be comfy below 20F. I wore all this in my house, and I needed to get out within minutes from overheating.

Looking for input on this system I'm trying to develop to keep me comfy from temps below 20 to above 70.

Thanks, Jeremy

One I have a similar system that I can use from about 45 degrees to about 20 degrees.

My bag is a 32F rated Nunatak quilt. I sleep warm so I can't really get much above 45 degrees in it, even with venting.

So my system is, for 45-30F:

Nunatak quilt, 32F
TiGoat bivy if sleeping under a tarp, no bivy if sleeping under fully enclosed shelter.
NeoAir small
1/8" closed cell foam pad sized to fit Neoair
backpack stuff with rain jacket under feet.
Synthetic insulation hoody (if if might rain) or Montbell UL Down Parka
Railrider pants
Merino Hoody
Golite Rain pants, if a few more degrees warmth is necessary
Mountain Hardwear Butter liner gloves.
Midweight (2oz) merino sleep socks.


For 30-20F

Nunatak quilt, 32F
Tigoat Bivy
NeoAir Small
Full length (70") trimmed to fit Ridgerest
backpack under feet.
Synthetic insulation hoody (if if might rain) or Montbell UL Down Parka
Railrider pants
Merino Hoody
Golite Rain pants, if a few more degrees warmth is necessary
Mountain Hardwear powerstretch tights or synthetic insulation pants
Mountain Hardwear Butter liner gloves.
Merino balaclava
Sleep socks
Feathered Friends Down booties(liners only if no snow)

I've been pretty comfortable with those two set-ups in the temperature ranges described. Ideally, I'd have a 40F bag(check), 30F(check) 20F bag(nope) 10F bag(nope) and 0F bag(nope, but I split the difference on the last two with a 5F bag)
on down, but that's a big investment. For the near term, I find a system of splitting the difference and working with stuff I'm already bringing to be a decent compromise.

I'd think below 30F, you'd want to add some sort of thin CCF pad along with the NeoAir as well, but otherwise, as a compromise system, it looks okay.

My thought is that if you are comfortable to 30F with the Hydrogen without the you down jacket and goose feet, then adding them in should give you that last 10F.

My system for similar goals isn't too far from yours. Hexamid as shelter. When I am expecting it to be below 40F I bring a MLD superlight bivy with DWR top to protect against drafts. Insulation is 2nd generation Nunatak Ghost (5in rather than the 10in between baffles if the 1st generation, but lacks the 3rd generation footbox), full length NeoAir XTherm pad. I typically am wearing modest weight wool socks, nylon hiking pants, light-weight long sleeve powerdry shirt, polar buff over head which gets me down to 30F. As it warms up the buff isn't worn, the light weight powerdry gets replaces with feather-weight top, and I am venting the quilt. When it's 15-30F I add a WM Flash Vest, a Downworks Down Bakalava, and Powerstretch gloves.

Below that... well, if it is surprise and I am not out for too many days then my head is inside the quilt. if expected to be <15F then I switch to a WM Versalite that I can sleep down to 0F wearing light base + hat.

--Mark

For me the important part that many miss is to have a clean and dry first layer (as well as a clean body) when you stop moving about in the evening and particularly when going to sleep.
So for example your feet will be warmer (if clean...) with the Goose Feet and without socks than having dirty sweaty socks on with the Goose Feet on top.
Try that at home...
In my case the 32f rated Summerlite works down to around 20f with a WM Flash top and bottom (total weight in down about the same as the 20f rated Ultralite) having under that a merino T and merino pants as well as coolmax socs and merino hat and liner gloves.
After an hour or so usualy the gloves and sometime the hat comes off and I open up the jacket, at around 4AM they go back on.(that is at around 20f)

Franco

I had the same bag and pad (have since gone to a quilt) and w/ base layer top, Cap 3 bottoms (my insulated bottoms for around camp), MB Exlight jacket, balaclava and gloves- I've been comfortable to about mid 20's (that was w/ a 1/8" ccf pad in addition to the neo)

you have a more insulated jacket and down booties, so you should be warmer yet

I will suggest adding a 1/8" ccf pad to the neoair for when temps could dip below freezing, right around freezing is pretty close to the limit of the original neoair imo

I believe that a 10F temp diference between bags is going a bit overboard. I usually use a neoair as a pad. Coupled with a Nightlite pad this gives me about an R4.6 below me. I use a Nightlight as a frame in my packs.

For bags, I have just two. A 40F and a 0f. Together, these are good for about -15F or so. I am comfortable sleeping to 60F in the 40F bag. With two layers of long johns (tops and bottoms), two wool socks and a down jacket, I have been down to 24F comfortably. Any lower and I would have brought the 0F bag.

Basically, I would have been lighter with a specific bag to 20F than adding all the cloths. but really, I only added one set for warmth... I carry one set for those times they are needed on the trail, and, to help keep the bag clean, anyway.

With sleep systems one of the keys I have found is to make sure there are no weak links. This means that you need the right quilt or bag, mat, head wear, socks and sleep clothes. Get any of these wrong and the whole system can be compromised. On a recent trip on the first night it was far too warm for me to use my Goosefeet down socks, so I just used my camping socks and all was well. On the second night it was much colder, but I started off with my hiking socks again. By now they were much sweatier and damper and I was soon feeling not just cold feet, but cool over. I switched to the Goosefeet down socks and within a few minutes I was warm all over and had a good night.

Thanks for all the replys. Guess there is only 1 way to test it out, and that's to use it. Will keep the 1/8" CCF pad in mind.