In six days on backcountry skis and with gear sleds across Europe's largest plateau. Across the continent's coldest chamber: the Hardangervidda in Norway! A treeless desert of snow, rock, and ice that stretches for almost 100 kilometers in all directions and, in winter, experiences temperatures as low as -30°C, winter storms, and changeable weather. A true challenge for both man and machine, requiring not only thorough preparation but, above all, high-quality expedition gear. I'm now pleased to report in detail how the Grüezi Bag Biopod Down Hybrid Ice Extreme – I was using the model with the final designation 190 W, the wide version with a comfortable cut – performed in the Arctic climate of the Hardangervidda.

The Hardangervidda in Norway: the largest plateau in Europe and a desert of snow and ice in winter

FRAMEWORK DATA

An extra-wide sleeping bag for winter mountain and trekking tours. Comfortably cut, lightweight, and compact when packed. A sophisticated hybrid construction made of the finest goose down (90/10, 800+). cuin(RDS certified) with an additional layer of alpine wool for optimal insulation and a dry sleeping environment. A comfort temperature range of -8°C, a limit temperature of -15°C, and an extreme temperature of -37°C.

So far, so good. The Grüezi Bag's product data sheet sounds extremely promising. What particularly interested me were the sheer number of additional features the Grüezi Bag was supposed to include: a carbon heating element for the foot area, an adjustable hood with a face baffle for a perfect fit, a 3D thermal collar, a two-way autolock zipper with an insulating cover, a zipper retention strap and anti-snag zipper to prevent pinching, anti-slip nubs on the sleeping area, and much more...

Many of these features were supposed to solve problems I'd always struggled with with my previous sleeping bags. Could that be true? If so, then the Grüezi Bag had to be the jack of all trades, or the beer-brewing noodle cow, of sleeping bags. I was therefore incredibly excited to be able to put the Grüezi Bag through its paces on such an extreme tour as the winter crossing of the Hardangervidda.

PREVIOUS EXPERIENCE

After more than 15 years of experience on mountain and trekking tours, including two and a half years of backpacking, trekking and adventure travel during a break, I have already put several sleeping bags through their paces. These included week-long treks, as well as long-distance trails lasting several months with tent and sleeping bag, mountain expeditions on 5.000 and 6.000-meter peaks, and winter overnight stays under the Northern Lights above the  Arctic Circle. And almost all sleeping bags had the same problems.

On the one hand, there were the temperatures in the so-called borderline or limit range, or the warmth and insulation capacity of the sleeping bag required for this. With my rather slim, wiry build, I have very little reserves and therefore probably hardly meet the ideal of the average tester, according to which the temperature range of a sleeping bag is determined. I'm the type who quickly gets cold in a sleeping bag. And in addition, I'm certainly the type whose body, in situations where it's already exhausted from the day's exertion, has even more trouble generating enough of the warmth it needs to warm the sleeping bag from head to toe. My most common problem was always my feet. Once I had cold feet, I rarely got rid of them again, and on tours where it was extremely cold and the temperature limit of the sleeping bag was approaching, I either found myself in the sleeping bag with freezing feet from the start, or I woke up at some point during the night because my feet were freezing. In most cases, neither a second pair of merino socks nor an additional thermal liner for the sleeping bag helped.

No -30°C, but we had Temperatures down to -25 at night°C: a tough test for the sleeping bag

The next problem was a very simple one: I kept sliding off my inflatable sleeping pad while I slept. Since I often travel very light and pack down compactly, I rarely carry a foam sleeping pad except in extremely cold conditions. However, these types of sleeping pads generally have a non-smooth profile. Inflatable sleeping pads usually have a nylon surface and a low structure. When I moved around at night—and I move around a lot and enjoy it—the combination of the smooth nylon surface of the sleeping pad and the usually equally smooth surface of the sleeping bag caused me to gradually slide off the pad, thus slipping into an area where the necessary insulation from below was simply lacking.

The third problem is also related to my nighttime movement. After all, I tend to turn around and around. And so far, all my sleeping bags have always turned around – at least partially. Usually, at some point, I'd end up lying in a sleeping bag so twisted that I lost all sense of comfort, or in the morning I'd be desperately searching for the zipper. It was, of course, no longer in its usual place. This was even more problematic with models that, to save weight, cut down on certain areas of the sleeping bag by insulating the area you were lying on. If the sleeping bag turned, that area would be on top or to the side, and I'd start to feel cold again.

You're probably all familiar with the last big problem: the zipper. Sure, I always managed to get it stuck at the most inconvenient times. And by that, I'm hardly talking about putting the sleeping bag away after airing it out. No, I'm mainly talking about those moments when it's so cold you just want to zip it up all the way to the very last tooth of the zipper, or when you have to get up in the middle of the night to go to the bathroom. Those were always the moments when I usually managed to get the zipper stuck in the lining of the sleeping bag several times... And of course, the zipper also often acted as a cold bridge in the sleeping bag. Quite often, the zipper itself was a problem, as at some point during the night it would hang in my face like the cold tip of an icicle.

THE FIRST IMPRESSION

I received the package with my new Grüezi Bag a few days before my flight to Norway, and thus before the winter crossing. And to be honest, I was incredibly excited about the brand's flagship product. In the days before the trip, I had a phone call with Markus, the founder and CEO of Grüezi Bag, who explained a lot about the sleeping bag, in particular the thoughts and considerations that had gone into the development of the Biopod Down Hybrid Ice Extreme and the sustainable strategy Grüezi Bag pursues in manufacturing its products. What I also really appreciated was their openness to any recommendations on how to further develop the sleeping bag.

The Biopod Down Hybrid Ice Extreme 190 W

Now let's unpack! So, the sleeping bag –  In a beautiful anthracite gray with a clearly visible white zipper and an elegantly embroidered logo on the side, it initially comes in the included large storage bag, which also features the Grüezi Bag logo sewn on. It also comes with a compression stuff sack, which you can use to compress the sleeping bag to an even smaller pack size if necessary. Since I was towing a gear sled, the so-called pulka, behind me on the winter traverse, the pack size was less important to me, at least for this tour. However, I was interested in how small the sleeping bag could be compressed for later tours with the Grüezi Bag, where this would play a more significant role. And it is astonishing. When unpacked, the sleeping bag puffs out so much due to the filling that, given the extreme conditions for which it was designed, it initially seems enormous. However, the included compression stuff sack allows it to be packed down to a diameter of just 20 x 30 cm. Some of you might be familiar with this from compressible down jackets. I'm always amazed, and I was no different here. Thanks to a winter bivouac I undertook after returning from the Hardangervidda in the Alps, I now know that I can pack the sleeping bag down to roughly the same size as my previous three-season sleeping bag. Unbelievable. And  even the compression pack is  of high quality. I've experienced other models in the past, and I have little concern that a strap or something similar might break.

The sleeping bag itself puffs up incredibly large, but above all, cozy, thanks to its filling. A few good shakes, and I immediately felt like I was sleeping on clouds: totally comfortable and soft. It should be a pretty nice feeling to crawl into the Grüezi Bag on a tour in double-digit subzero temperatures. The wonderfully puffy down filling would—   I was convinced of that –  ensure a comfortable night's sleep and a pleasant sleeping environment. In my experience, down simply has a clear advantage over synthetics in this regard. And here, the down is combined with a layer of purest Alpine wool for a drier sleeping environment. I'm not aware of any other sleeping bag that offers this, and it's probably a unique selling point of the Grüezi Bag. You can recognize these sleeping bags by the product name "Downwool."

Of course, I tried it out right after unpacking it, and for me, at 1,80 m tall, the sleeping bag's length of 1,90 m and its cut were perfect. I immediately felt a pleasant sense of freedom of movement. I could also move around in the sleeping bag without it moving or twisting.

So my first impression was really good and to be honest it has rarely been A product that was so successful right away. That gave me a very good feeling. My tour partner and I had already thought about it in detail before the tour! From the exact route through the Hardangervidda, from the expected arctic conditions to the type of physical and mental preparation, right down to the type and, above all, the quality of the necessary equipment. We had invested a lot of effort in a short space of time into tackling something that we had barely any idea about just a few weeks earlier – I had never done much cross-country skiing in my life, nor had I ever used a pulka – and now, just before the tour, I had a very good feeling about the piece of equipment that, to be honest, had been on my mind the most. Nevertheless, since we were expecting temperatures well beyond the sleeping bag's temperature limit, I took a thermal sleeping bag liner with me as a backup. With this, I could have increased the warmth of the Grüezi Bag by a few degrees Celsius in an emergency.

THE BIOPOD DOWN HYBRID ICE EXTREME IN PRACTICE

Of the five nights we spent on the tour, we slept in expedition tents for three nights, the coldest of which was -25°C. I was extremely excited beforehand to see how the sleeping bag would perform in practice. My excitement was all the greater, perhaps even slightly tense, because my tour partner had borrowed a sleeping bag from an expedition outfitter for our tour whose temperature range was about ten degrees lower than my sleeping bag. The impression of superior insulation was even more emphasized because his borrowed sleeping bag was more than twice as large and heavy as my sleeping bag. However, his sleeping bag was also a synthetic fiber sleeping bag, which are usually significantly heavier and less compressible for the same level of insulation.  If I still had any initial uncertainty about the heat output, it completely disappeared after the first night outdoors with nothing but snow and ice around us.

With backcountry skis, expedition tent and the Biopod Down Hybrid Ice Extreme on 125 kilometers through the ice

To protect myself from the cold below, I slept on a combination of two sleeping pads: a foam one underneath, with an inflatable all-season mat on top. Then I placed the Grüezi Bag on top. Crawling into the Grüezi Bag felt incredibly cozy and warm every time. It wasn't the cramped conditions I was used to with other sleeping bags. And even with all the electronics I brought with me to protect myself from the cold, the wide, comfortable cut gave me all the freedom of movement I needed to sleep comfortably. The hood fit snugly around my head without being too bulky, and a wide, cozy bulge at the opening prevented cold air from seeping into the sleeping bag from above. 

That first night outside, it wasn't quite -20°C, and I slept comfortably warm. This was only a short time after I had preheated my typical problem area, the footwell of the sleeping bag, to a truly comfortable temperature using the integrated heating element, much to the delight of my feet. All that was needed was a standard power bank, which I had with me anyway. In the chest area of ​​the sleeping bag, there's an inside pocket, behind which is a USB port for powering the heating element with the power bank. Let it run for 20 minutes, and it's pleasantly warm. Not only my tour partner envied me, but also everyone else I've told about the Grüezi Bag in the meantime.

In cold weather, the blood vessels in the outermost limbs, such as the hands and feet, constrict significantly faster than in the rest of the body. For me, this sometimes feels like a record-breaking pace. And since a sleeping bag can only retain the heat you generate in the bag, this is a problem, especially in the foot area, as mentioned above. With the integrated heater, my feet warmed up pretty quickly, and to be honest, I barely noticed that a lot of energy was being lost from my power bank. 

Since the temperature dropped below the sleeping bag's temperature limit on the first night, I started by wearing several layers of merino underwear in my Grüezi Bag: short merino shorts under long merino underpants, thin merino liner socks under insulating 800-weight merino socks, a long-sleeved merino shirt on top, and a warm fleece jacket over that. While my tour partner shivered in his sleeping bag in considerably thicker gear, including an additional down jacket, I gradually removed one layer after another during the night – without twisting the sleeping bag – until I was finally wearing just one layer of merino. It's incredible how much warmth the sleeping bag retained! I was, and still am, completely amazed.

The second night was the coldest of the tour: -25 ° C This time with two layers of merino wool and a merino face mask, but still without a thermal liner. The absolute endurance test of the tour! Temperatures equivalent to those in a 4-star freezer and 10 degrees below the sleeping bag's temperature limit... according to the data, the sleeping bag shouldn't have been able to cope without me constantly freezing. And I, completely exhausted from a strenuous day in snow and ice... felt right at home in the sleeping bag and only shivered for a few moments during the night. And despite the extreme temperatures, my sleep on the night with the lowest temperature of the tour was still restful. The sleeping bag proved absolutely reliable, retaining heat even in extremely cold conditions. And I didn't feel any cold spots, nor did I have to contend with an ice-cold zipper on my face thanks to such well-thought-out details as the drawstring pocket for stowing the zipper. If there was anything cold, it was the snow crystals that had fallen on the walls and ceiling of the expedition tent during the night due to our condensing breath. And if I hadn't taken my water bottle, which I'd left outside my sleeping bag and had practically frozen into a block of ice, into my Grüezi Bag around midnight, I might not have even shivered slightly during the night. Because if I did, it was at those moments when my body was touching the cold water bottle, thus triggering the opposite effect of a hot-water bottle.

Temperatures equivalent to those in a 4-star freezer. The Grüezi Bag delivered more than it promised.

The other problems I'd experienced with my previous sleeping bags were also solved in the Grüezi Bag: the three anti-slip nubs on the back of the sleeping bag reliably prevented me from slipping off the sleeping pad during the night as usual. I hate to miss them! How often did I wake up in cold weather because I'd slipped off the rather narrow sleeping pad, which was supposed to provide insulation underneath. Those days were over! Problem solved! 

And the combination of anti-slip nubs and the bag's loose fit actually allowed me to move around in it at night without it twisting and turning with every movement. Whether I wanted to turn over, lie on my side, tuck my legs in or stretch them out again, take off a pair of socks or an over-worn top... the sleeping bag offered me all the freedom of movement I needed without feeling lumpy. Another of my problems: solved! 

With the Grüezi Bag through the vastness of the Hardangervidda

What amazed and delighted me most, however, was the zipper. The system with its retention strap and anti-snag zipper worked flawlessly throughout the entire trip, so much so that I never once caught the zipper on the sleeping bag lining. I was used to that completely differently, and—oh my God—how it always bothered me... Problem solved!

Incidentally, on the tour we consistently encountered freezing cold but dry conditions, so I wasn't able to fully test the performance of the AlmWolle layer, which serves as the outermost layer of the sleeping bag and is supposed to protect the down from moisture. However, I did experience more humid conditions during the winter bivouac after the tour and can confirm that the sleeping bag lost none of its thermal performance despite a partially wet exterior.

As an additional feature that I haven't yet discussed, the Grüezi Bag has an outside pocket at shoulder height next to the logo, which can be used to store a cell phone or similar. While not essential, it further enhances the sleeping bag's functionality. There are also other thoughtful details, such as the zippers being all white for better visibility in the dark.

Ski expedition Norway/Sweden

On an expedition to Sulitjelma / Padjelanta in the border region between Norway and Sweden, Nils tried the following products:

• The Lightful DownWool Jacket
• The Refreshful Silk Wool Jacket

On the tour in late winter 2023, he was out with cross-country skis and a pulka and was able to tell us:

"I wore the Lightful DownWool on its own down to temperatures of around -15°C. Underneath, I always wore a long-sleeved 260g merino shirt and a warming fleece mid-layer on top. I also wore a thin Buff merino neck warmer. When it was significantly colder, I added a light Polartec vest as an additional layer. The combination worked really well for me, not only in the sun, but also in wind and snow. I must say, though, that I was very active most of the time. Cross-country skiing is considered a full-body workout, and especially with the heavy sled on the back, your body naturally generates an incredible amount of heat.

In the evening or at night, when temperatures dropped to -30°C, I usually wore another high-quality down jacket, etc. This often included an additional layer of merino wool. Of course, at temperatures like these, you also reach your limits, which place different demands on the jacket.

I also wore the SilkWool for two days, also in the same situation (exercise, occasional breaks). Its temperature range is, of course, lower, but its purpose isn't to withstand such extreme temperatures, but rather to create a comfortable climate during athletic activities (ski touring, etc.).

I'm currently doing a lot of mountaineering with both jackets. Most recently, I was on a high-altitude tour on the Weißkugel a few weeks ago, for example, at around -10°C.

In the plus range, both jackets are incredibly well-suited for wear up to an estimated 15 degrees Celsius (without physical activity). The climate is simply fantastic in both jackets."