The Big Agnes Lost Ranger is a 15 degree, down, sleeping bag. While the bag falls into the “classic” series that Big Agnes offers, there’s really nothing traditional about. First, it includes the fancy new DownTek technology, which adds a water repellent compound to the down feathers. Secondly, the sleeping bag has no insulation on the bottom of the bag, instead relying on your sleeping pad for insulation. The idea is that flattened insulation under your body weight no longer insulates, as there is no air left trapped to keep warm. Does it work? Let’s see.
About the bag
The bag weighs in at around 2lb, 11oz for the regular size. Shoulder girth falls in at a room 70”, and the hip girth is an unusually spacious 66”. Retail is 239.95 for the regular, and 259.95 for the long. Left and right zippers are available. The bag comes complete with a pillow pocket, and internal attachment points for sleeping bag liners. Include with the bag is a mesh storage sack, and a quality stuff sack.
What I liked
This thing, it’s comfy, and not just comfy for a sleeping bag. This thing provided several of the best nights sleep I’ve had, period. It’s like sliding into a soft bed of air, wrapped in warmth, especially when paired with the Insulated Q Core SL. The materials are silky, and feel amazing against the skin. It’s pretty light for it’s roomy size. The bag is made wide and deep which allows you to toss and turn inside the bag, while leaving the sleeping bag in place. It’s one of the roomiest bags I’ve ever tested. The sleeping pad actually slides inside the bag, which ensures that you never slide off, and you don’t have to worry about cold spots when you change positions. Surprisingly, having the sleeping pad (Insulated Q Core SL was tested with this) on the bottom increases the warmth of the bag in our tests, despite having no down on the bottom of the bag. The way the sleeping bag wraps around the sleeping bag eliminates any drafts. Huge fluffy draft collars snuggle up with you to keep any air from coming in or out. The zippers slide gracefully with little effort. Despite the 15 degree rating, I’ve used it all the way up into the 50’s and stayed comfortable, without getting too hot or sweating. Finally, the Downtek seems to work. On a particularly muggy night the tent became saturated with moisture on the inside, and soaked the foot of my bag. Normally, the down would be flattened a bit, but it held it’s loft like a champ, and dried quickly. Extra perk, you can zip two of these sleeping bags together (right and left zip) for a little cuddle action.
What I didn’t like
The sleeping only has a zipper on one side, without a partial zip on the other. So you can’t turn towards the zipper side without having some sleeping bag in your face. Probably closer to about a 20 or 25 degree bag if you like to be super warm at night. It has to be paired with a sleeping pad to function properly. Otherwise, you’ll have a cold back.
overall
There really is very little to complain about with this bag, and I was being picky. The wide comfort range of temperatures for this bag, about 25 to 55 fahrenheit, makes it a formidable 3-4 season bag. It’s light, and decently affordable for a quality down bag. The comfort can’t be matched, especially if you’re a flip flopper like myself. I fell in love with the pad inside the bag design.
Recommended without question.
TreeLineBackpacker 
I have a BA sleeping bag, not this one, but similar in pretty much everything except that it’s not down.
The sleeve that the air mat goes into is wonderful! No matter how much you toss and turn, you never roll off the pad. I’ll never use a sleeping bag without this feature again. Pretty easy to get it in there, and the way it’s made guarantees you’ll have the mat in the right place. I upgraded to a Thermarest Antares that has the same feature, but I don’t think it’s as well done.
And the roomy interior of the sleeping bag is really, really nice. I still use mine for car camping, and when I do I feel a lot more like I’m in bed at home than like I’m out in the wild lands sleeping on dirt.
The Antares is getting a lot of attention these days, I may have to check that one out myself. I don’t know if BA is the first to come up with the pad in sleeve design, but it certainly works. It would be hard to go back.
I shivered so much I woke myself up….we were in a BA tent with four people and a dog…lots of heat. My new Lost Ranger was roomy enough and I loved the pad comfort. It was 30 most of the night dropping to 28 at 3am. I know this because I was freezing. I had coldspots along the pad insert that I filled with a polar fleece. The hood system was hard to close for a side or stomach sleeper and I wish I had brought my 30+ year old TNF bag to switch into at 3 am!.
I love the design, the weight and even the build but it won’t work even in Arizona’s mild spring or fall…..at best a 40 degree bag.
That’s quite unusual. What sleeping pad were you using under it? If you’re using a non-insulated sleeping pad, you’ll be cold all night. These are designed to use that insulation.
If you have too much room in your sleeping bag, this can also cause you to get cold in the night. Your body can only heat up a very small amount of air. So, while a roomy sleeping bag is good for some, if you’re a cold sleeper, and particularly small, this one might not be your best option.