Big Agnes Flume UL 30 Degree Sleeping Bag – 850 DownTek Fill

Big Agnes Flume UL 30 Degree Sleeping Bag is an ultra-lightweight technical mummy-style bag for ounce-counters, hikers, mountaineers, and backpackers with 850 DownTek treated down fill.

Key features & benefits

What this is about

Here you have a technical and ultra-lightweight sleeping bag and this you realize when you see its weight of 1 lb 6 oz (624 g) for the size R. You will be able to compare this with some of its competitors, there is a comparison table below. So if you are puzzled with the letter UL in the name of this bag, now you know, they mean ‘ultralight’.

They have managed to build it so lightweight by trimming its size so you have a typical mummy-style design, but you will also notice that it has a very short zipper to save the weight, see the picture. Such a shape together with some extra features effectively increases its thermal value.

Who is it for

Seasons-wise, this bag is suitable for temperatures as low as 30 F (-1 C). I have seen at some places they mention EN rating, but I have checked at the manufacturer’s site and have not found such a piece of information. So I cannot confirm such information, and without such an extra rating, I would take those numbers above cautiously and add some 10 degrees or so for comfort. But clearly, this is a bag suitable for most situations in a 3-season use.

But in view of its short zipper, it may not be perfect for situations where you want to swing your feet or legs out. So it is better suited for a cooler environment than as a typical summer bag.

Weight-wise, this is where this bag shines. I already mentioned the weight above, so it is quite extraordinary. This makes it a perfect item for backpackers and ounce-counters.

Size-wise, they build this bag in R and L sizes, see the numbers in the specifications below, so this is a model for men. The two sizes fit 6 ft (183 cm) and 6 ft 6 inches (198 cm), respectively. Note that they also have the Big Agnes Hitchens UL 20 bag which is officially unisex, with the S size as well.

Regarding the packed size, the declared numbers are in the specifications below. But this is not what you have unless you order a stuff sack with compressions straps. In this case, this is an ultra-packable sleeping bag.

Materials & construction

The insulation

Here you have Big Agnes’ DownTek which is an 850 fill water-repellent down insulation. So this explains its weight and great packability, but also its high price as this is top-quality insulation. In view of its excellent warmth-to-weight ratio, this is a bag for backpackers and thru-hikers, and also for mountaineers.

The natural down, when used in sleeping bags and jackets, is susceptible to moisture and it loses its insulation properties when wet. So they use a proprietary technology to increase down’s water-repellency and to add anti-microbial protection.

You have a body-mapped baffle construction with structures that trap the heat closer to your body and this all optimizes the bag’s thermal efficiency. This eliminates cold spots and reduces weight. This design is what they call the Insotect Flow construction.

But this thermal efficiency is also helped with its 3D anti-snag draft tube that runs along the 40 inches zipper (shown below) and prevents heat loss. The foot box is particularly ergonomic and it provides more loft and warmth.

The fabric

I have only seen statements about the high tenacity and ultralight shell fabric, but have not been able to find some numbers about its denier value to show. But this is a soft and pleasant nylon rip-stop with a water-repellent finish. You also have a nylon rip-stop lining inside.

Other features

• The hood is insulated and contoured.
• Included are a mesh storage sack and nylon stuff sack.
• Note that you have integrated internal loops for a liner that is sold separately.
• Exterior loops for hanging when drying or for storage.
• The zipper is the best quality 40 inches (102 cm) YKK #5.
• It can be zipped in with another bag to create a double bag structure.

Please see more in this video:

Specifications

• Type: mummy-style sleeping bag.
• Best use: backpacking, hiking, mountaineering, travel.
• Sizes: regular (R) & long (L).
• Weight:
  – R: 1 lb 6 oz (624 g).
  – L: 1 lb 8 oz (680 g).
• Fill weight:
  – R: 12 oz (340 g).
  – L: 14 oz (397 g).
• Compressed size:
  – R: 7 x 5.5 in (18 x 14 cm).
  – L: 8 x 5.5 in (20 x 14 cm).
• Stuff sack size (R, L): 15 x 7.5 in (38 x 19 cm).
• Fits:
  – R: 6 ft (183 cm).
  – L: 6 ft 6 in (198 cm).
• Circumference (shoulders/hip/knee):
  – R: 60/54/36 in (152/137/91 cm).
  – L: 62/56/38 in (137/135/86 cm).
• Zipper: YKK #5.

Big Agnes Flume UL 30 bag vs Competitors

Here I show you this Flume UL 30 bag side by side with two other bags with the same temperature range, just to get some idea of what you have here, those are all top brands and top models. You realize how incredibly light this bag is. Please follow the links for more.

Final thoughts, rating, pros & cons

Note that the declared packed size is not what you really have, the carry bag is not with compression straps. What you get is an ordinary stuff sack which is far bigger, but the sleeping bag can be compressed to the declared value. So my rating would be 10/10 if they provided such a compression sack, but I give it what you see in the rating table below.

Please see how I rate it for several parameters used for all sleeping bags here in the site, so you can make an easy comparison.

Big Agnes Flume UL 30 Downtek Mummy Sleeping Bag

9

Weight

9.4/10

Packed size

10.0/10

Temperature rating

8.5/10

Comfort & features

8.2/10

Pros

• Great weight.
• Quality fill.
• Great packed size, if you order another sack.

Cons

• Very expensive.
• No compression straps on the stuff sack.

Please visit my page with sleeping bags if you need to see more options, and also check my text with the best 3-season sleeping bags where this Flume UL 30 bag is also included.

Note that I am not paid by the brand or related in any sense, so this is NOT a sponsored text. I only give my unbiased view of the product.

Thank you for reading. Please let us know if you have any experience with this bag, there is a comment box below. Have a nice day.