Icebreaker 260 ZoneKnit Merino Leggings - Women's Review

The 100% Merino Icebreaker 260 ZoneKnit Merino Leggings feature thoughtfully placed ventilation panels to maximize breathability without causing discomfort or friction. The latest update is constructed from ultra-fine 18.9-micron fibers for softness next-to-skin, while the slim fit and flatlock seams increase layering ability by reducing bulk. The combination makes these bottoms a perfect match for athletes during the coldest months of the year.

Performance Comparison

Warmth

The 260 ZoneKnit is one of the warmest long underwear bottoms we've tested. Its 260 g/m², 100% Merino wool construction effectively harnesses body heat. This warm construction is balanced by the body-mapping technology for enhanced ventilation zones, which shed excess moisture through the perforations. The zoned temperature regulation performs best while in motion, so we recommend wearing these tights for the high-output winter activities they were designed for. The bottoms also feature a high waist, providing additional heat for your core.

While these bottoms' thick, tightly woven cut is super warm, they would not be our first recommendation for those cold weather days riding the chairlift. These bottoms excel during fast-paced winter activities like training runs, nordic skiing, and backcountry skiing because they are so good at trapping body heat generated while in motion. That said, one could effectively compensate for any heat loss by using a thick ski sock to cover the perforations on the lower leg to help turn up the heat for more sedentary days.

Breathability

If the 260 ZoneKnit bottoms don't scream breathability, we don't know which pair does. Literally half of the fabric features a uniquely engineered, body-mapped technology designed to enhance the natural breathable capabilities of Merino wool. These panels are designed to manage moisture in locations where it tends to build, and we all know our favorite layers don't insulate well when they're wet.

The latest update for the 260 ZoneKnit features even more ventilation than iterations we tested previously. The panels are located on the lower back, the back of the knee, and over the entire lower leg. This layout significantly changes zoned temperature regulation, efficiently wicking moisture away from your skin and upping the ante for overall breathability. While we wouldn't recommend these super warm bottoms for year-round use – they're still too hot for warmer temperatures – they are the perfect base layer for the colder months of the year.

Comfort and Fit

The 260 ZoneKnit offers a slim-fitting silhouette designed to fit close to the body, and we love the color-blocked pattern. Since we've tested a few different iterations of the same bottom, we appreciate that the latest update features a fit that remains true to size. However, it doesn't feel as rigid as the previous versions, which allows for more stretch during activity without losing its overall structure.

The latest 260 ZoneKnit also feels even more comfortable next to the skin, perhaps because of the purely 100% Merino wool design. Ultra-fine merino wool fibers, thoughtfully placed flatlock seams, and a gusseted crotch allow a full range of motion without any friction. After testing lots of long underwear bottoms over the years, we truly appreciate thoughtful seam placement. The seam on the front of the leg rests just below the knee, while the seam on the back of the leg is located just above the knee. This placement makes the seams practically undetectable, limiting any friction or discomfort from any layers above.

Durability

We did not experience any durability issues with the 260 ZoneKnit during our testing period. However, we remain skeptical about the longevity of this full-Merino, partially perforated construction. As mentioned, this is not our first rodeo with the 260 ZoneKnit. Previous designs featured an elastane and nylon blend that was typically the only point of failure, often running like pantyhose between the perforated ventilation holes. Even though we can tell a significant difference in the construction of this new, 100% Merino version, we will report back if longer-term testing results in any material failure.

Although the perforated ventilation panels are larger on the latest update, the fabric is thicker and more malleable. In fact, after many miles in these bottoms, the only weakness in the design is minor piling between the legs. We also love that Icebreaker kept the thicker 260 g/m² Merino wool over the knees, often one of the first places our long underwear will fail. It is also worth mentioning that this thicker, more durable, 100% Merino wool construction also effectively resists any odor. We plan to spend the upcoming winter earning our turns in the mountains and will be sure to update you on any findings we make along the way.

Drying Speed

Unfortunately, the trade-off for any heavier-weight pair of long underwear bottoms is often a slower drying speed. We conducted our line drying test in Bishop, California, on a sunny fall day with temperatures near 60 °F and 9% humidity between 1:30 and 2:30pm. Of the layers we tested, the 260 ZoneKnit required one of the longest drying times – 51 minutes, to be exact. This extended time is not unexpected due to the thicker, 260 g/m² 100% Merino construction. However, we hypothesized a faster speed, especially considering the significant amount of ventilation panels.

Our other drying speed tests involved speed intervals on the very same day, which is why we do not recommend these incredibly warm bottoms for warmer temperatures. They performed far better on a cloudy, 30-degree day in the mountains outside Crowley Lake. These bottoms offer enough barrier against the cold and effectively shed moisture through the ventilation panels. We especially appreciate the panel below the waist, which helped dump body heat and sweat that typically collects in that area. These bottoms are built for the athlete who wants to keep it moving during the coldest months of winter, offering enough ventilation to shed moisture and enough coverage to maintain insulation when properly layered in a system.

Layering Ability

The slim-fitting 260 ZoneKnit is designed to maximize warmth without adding a ton of bulk. Even though the high-waisted fit has a thin, brushed-elastic waistband rather than a thick waistband, these bottoms are still easy to layer. The natural waistline rests perfectly between the waistband and the flatlock seam below.

Even though the 260 ZoneKnit features some of the densest fabric weight of any bottom in our lineup, the interface remains smooth with the layers over the top, especially over the thinner perforated ventilation panels on the lower leg. Whether layering below your favorite fleece pants or beneath a hard shell, these slim-fitting bottoms will layer easily without adding excessive bulk to your cold-weather kit.

Should You Buy the Icebreaker 260 ZoneKnit Merino Leggings?

If you want to invest in a high-performance pair of long underwear bottoms that deliver warmth and breathability, look no further than the 260 ZoneKnit. These 100% Merino bottoms offer enough ventilation and wicking capabilities for the most demanding winter sports. The thick, 260 g/m² fabric weight feels soft and cozy next to the skin, the fit is true to size (though less rigid than the previous versions), and the bottoms are super easy to layer. Whether out in the backcountry earning your turns or picking up the pace on the groomers, these leggings will keep you warm and comfortable all day.

What Other Long Underwear Should You Consider?

If you dig the cold weather performance of the 260 ZoneKnit but prefer a pair of long underwear that can also be worn as a standalone bottom, check out the Smartwool Intraknit Thermal Merino Bottom. These bottoms perform well independently, especially during cold weather runs and on Nordic skis. If you're looking for a more affordable Merino option, the Minus33 Franconia Midweight Wool Bottom should be on your radar. Or if you want the same comfort and breathability of the 260 ZoneKnit in a very similar yet more lightweight model, you can't go wrong with Icebreaker's 200 version. If you tend to run cold and need to maximize warmth, check out the Ridge Merino Inversion Heavyweight Merino Leggings. These are more traditional long underwear bottoms with a high waist design.