ProView – The Big Agnes Zirkel UL 20 Sleeping Bag and Q-Core SL Pad


Ben Horan is a freelance writer and sometimes-guide based in Missoula, Montana, and blogs at (follow him on Instagram: @thegentlemanatlarge). Tom Robertson is a photographer out of Missoula, whose work has appeared in a variety of national and international publications, and is currently surfing from bike tour to bike tour around the Americas. Ben, Tom, and two buddies rode bikes from Portland to Bend, OR, with trailers full of ski gear, in an attempt to ski as many volcanoes as possible in two weeks entirely under human power. Check out their adventure on Instagram #bike2skiOregon. They also had some times to test some gear along the way! 

On a trip where packing light is the biggest priority, most gear is negotiable. You can leave the tent and you can leave the stove, but if you’re planning on camping you’re probably still going to reach for the sleeping bag. We got our hands on the 3-season ultralight offerings from Big Agnes and took them for a spin. If you like the Big Agnes design model, you’re going to love the Zirkel UL 20 sleeping bag  (Tested: 2lbs 7oz – Size Long, MSRP: $469.95). If you’re new to this small Colorado company’s innovations with sleeping bag design, you might find that it takes a little getting used to.


Initial Impressions

At my house we’ve got a routine for when a new piece of gear comes. First the dog barks at the FedEx guy. Then the FedEx guy, we’ll call him James, says, “You are a big softy. No one is afraid of you,” and gives the dog a cookie. The dog wags her tail. Then James comes through the gate and I apologize profusely and it’s awkward for a moment and then the dog barks again as James is leaving and feels as though she has protected the home and is very satisfied with herself. Then I go play with whatever new gear it is in the living room.

The Zirkel UL 20  feels plush, lofty, and soft. The Q-Core SL  (19 oz., MSRP: $219.95)  pad took several minutes to inflate and left me lightheaded, but I was impressed by how big it got. The pad deflates and folds very small; it’s much more compact than non-inflatable pads and deflated is comparable to a lightweight Thermarest. Inflated, the Big Agnes pad is significantly larger and thicker than the Thermarest NeoAir that I had in the basement.



They grey and yellow coloring on the sleeping bag seemed true to the website. I liked the clean, non-gaudy lines. The yellow may show dirt over time, so you may not want to wear this sleeping bag out to a fancy dinner or to meet your fiance’s grandparents.


More than a decade ago, Big Agnes set themselves apart from the rest of the sleeping bag crowd with an integrated bag/pad design. By combining two things that you’re probably bringing at the same time anyway, they managed to improve comfort and reduce weight by eliminating redundancy. The pad slides into a sheath on the bottom of the sleeping bag, which keeps you from sliding off in the middle of the night. And because it’s the pad, not the down, that keeps you insulated from the ground (compressed down doesn’t keep you warm), Big Agnes removed the down from the bottom of the torso section. This way they use less material which decreases weight and packed size, while maintaining the same insulating performance and warmth of competing bags.


The Big Agnes system works, but it takes a little getting used to, and slightly reduces the versatility of the bag. In a month of fairly heavy use, the integrated design has been awkward in two scenarios. The first is when it’s cold. When it’s chilly, I like to sit up in my sleeping bag and put on a down jacket while still bundled. If the bag is strapped to the pad, it’s tricky to sit up comfortably. It works great when supine and sleeping, it’s less great for moving around in your bag.

The design is also a little awkward when it’s hot out. The Zirkel is a 20 degree bag, and arguably not appropriate for steamy, humid, July nights. But with alpine weather being as variable as it is, I like to have some versatility built into the bag. If it’s cold I zip up, and when it’s warm I’ll usually unzip the bag all the way and use it like a down blanket.This design doesn’t really allow for that. You can easily remove the pad from the sheath and use it more traditionally, but remember that the sleeping bag doesn’t have down along half of the torso, so it’s only half a blanket. These are small inconveniences, but noteworthy. Ultimately, it’s up to you to decide whether the warmth, weight, and comfort of the bag is worth the trade-offs.


I’m 6’3” and ordered the tall size, which is rated to hold someone up to 6’6”. I thought it felt true to size. The only thing worth mentioning here is that the pad sheath stops a few inches below the head of the sleeping bag. I didn’t have an issue fitting both in the bag and fully on the pad, but someone who’s planning on using the full six and a half feet might.


At the end of the day, a sleeping bag is best judged by how well it keeps you warm. In the summer months I never had the opportunity to push this bag to its 20 degree rating, but one night did drop to the low 30s, and we woke up to frost on the grass and leaves. That night I slept with the bag fully zipped, and didn’t notice any cold spots. I’ll keep sleeping in this thing once the seasons swing a little bit and update its cold weather performance in the comments section.

Zirkel UL 20 front-zm


When you reach for down over a synthetic insulation, you’re choosing warmth, compressibility, and light weight with the understanding that you’ve got to keep it dry. Big Agnes went with a Pertex Quantum shell and liner material for the Zirkel UL 20, and 15.5oz (size Tall) 850 fill DownTek down for their high-end line of sleeping bags. In my experience it’s great.

The mountain west is in the midst of an historic drought, but I’ve still managed to do a lot of camping in the rain this spring. I also have sweaty feet, and with other down sleeping bags frequently wake up to find the bottom of the bag soaked through and cold. (I have really sweaty feet.) The combination of a wicking Pertex nylon and the hydrophobic down has worked well for me so far. I noticed a little bit of clamminess in the footbox at first, but the wicking material performed as advertised and pulled the water out. I was mostly impressed by the fact that while the foot of the bag did get wet from sweat and condensation on the tent fly, the down retained its loft and my feet stayed warm. I made an effort to dry the bag as well as possible before packing it, and so I don’t know how it stands up to sustained dampness. However, after several consecutive days of camping in the rain the bag stayed lofty.

Notes on the Pad

After a few weeks, the Q-Core SL pad developed a ghosty slow leak that I’ve been able to find by listening closely or submerging the pad. It’s slow enough that I can fall asleep on a full pad, and wake up to a half deflated one an hour or two later. The other two guys who tested the same pad have not experienced the same issue. After a brief email exchange with the customer service folks over at Big Agnes they pointed toward their 100% satisfaction, no-questions-asked exchange policy on inflatable pads and dropped a replacement in the mail same day.



I liked it! For me, the nuances endemic to the Big Agnes design model are worth it, and I’d probably order this up again. I’ve only used it in the summer, but I think that it will really shine in the fall and winter, when I’m spending more time with the bag fully zipped. For those people who aren’t sold on the integrated design, Big Agnes offers the McAlpin & Bellyache, which features of the same construction but in a more traditional shape.

The shape was comfortable and the material soft, and the combination of modern down and wicking fabric worked surprisingly well in staying dry and lofty in damp conditions.


  • Light weight
  • Packs small
  • Wicks moisture and stays dry
  • Excellent customer service


  • Endemic design quirks
  • Price
  • Versatility

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2 thoughts on “ProView – The Big Agnes Zirkel UL 20 Sleeping Bag and Q-Core SL Pad

  1. Zirkel UL 20 open-sm. The Divide Ultralight series, with a new color palette for ’15, is our most technically oriented line of Big Agnes System bags, using our minimalist half pad sleeve design and super cozy 850 fill power DownTek™ water repellent insulation.

  2. I’ve had 15-20 nights in the Zirkel UL 20 so far, and no surprises. The zipper is still smooth, the feathers have stayed put, and the hydrophobic DownTek down really does seem to hold its loft when it gets a little damp.

    I’ve reverted back to a Thermarest pad, though. The Big Agnes pad is really comfortable and offers great support, but the leak problems persist.

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