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Icebreaker BodyfitZone Merino 260 Zone Thermal Leggings Review

A technical performance base layer bottom for high output activities when you need both the warmth of wool and enhanced breathability in key areas
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icebreaker bodyfitzone merino 260 zone thermal leggings long underwear review
Although the thinner wool panels of fabric used for areas like the knees enhance breathability, they're also more delicate and will most likely fail before any other part of the legging.
Credit: Maddock Rigby
Price:  $140 List
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Manufacturer:   Icebreaker
By Justin Simoni ⋅ Review Editor  ⋅  Dec 2, 2022
  • Warmth - 25% 7.0
  • Breathability - 20% 8.0
  • Comfort and Fit - 20% 7.0
  • Durability - 15% 4.0
  • Drying Speed - 10% 9.0
  • Layering Ability - 10% 9.0

Our Verdict

Does a pair of wool bottoms sound enticing, but you're prone to overheating and sweating? The Icebreaker BodyfitZone Merino 260 Leggings are built for you. These technical bottoms pair the excellent warmth of ~150-200 g/m² Merino wool with thinner, breathable panels of around the knees, back, and crotch. Wool blended with just a touch of elastane and a next-to-skin fit helps hug these woolies closely to your body and wick excess moisture away. Flatlock seams throughout and a gusseted crotch also give you a high degree of mobility. Just be especially mindful when caring for these bottoms: the thinner wool panels are prone to ripping if abused.
Enhanced breathability in key areas
Merino wool blend is soft and warm for its weight
Breathable mesh prone to ripping

Our Analysis and Test Results

We love when companies come out with truly innovative products that work well. Enter the Icebreaker BodyfitZone Merino 260 Zone Thermal, with its unique mix of mid and lightweight wool fabrics constructed to enhance both warmth and ventilation. Think of these as the luxury car of the long underwear world; they aren't made for taking your kids to school, then off to Costco — although if you'd like to incur additional wear and tear, be our guest. What they excel at is keeping you warm and dry while covering some serious miles in the cold and snow.

Performance Comparison

icebreaker bodyfitzone merino 260 zone thermal leggings long underwear review - the icebreaker bodyfitzone merino 260 make an excellent pair of...
The Icebreaker BodyfitZone Merino 260 make an excellent pair of leggings for fast and light missions in the high country.
Credit: Justin Simoni


The BodyfitZone Merino 260 is designed to be worn comfortably in the cold, so long as you keep your heart rate up. They won't excel if you're standing around, as the built-in ventilation panels will leave you a little more exposed than you may otherwise prefer. These could make great bottoms to sleep in during the summer but won't cut it for most people in more wintry conditions.

Icebreaker doesn't give a weight for either the main fabric or the panels on these bottoms, but we wager the weight of the main fabric to be around 150-200 g/m² and the ventilation panels more like a svelte 100 g/m², making the overall warmth effectively similar to a 150 g/m² 100% Merino wool bottom — just expect far better breathability.

icebreaker bodyfitzone merino 260 zone thermal leggings long underwear review - the main fabric of the  icebreaker bodyfitzone is around 150 - 200...
The main fabric of the Icebreaker BodyfitZone is around 150 - 200 g/sm, with the more ventilated panels being much thinner.
Credit: Justin Simoni


Warmth and breathability are closely correlated in 100% Merino wool base layers. As the overall warmth of a base layer goes up, breathability starts to decline because it's not as easy to transport excess heat and moisture to the surface of a thicker fabric. Icebreaker does something clever with the BodyfitZone Merino 260 Zone, where areas of higher perspiration are covered by panels of much thinner, more ventilated wool fabric than you'll find throughout the rest of the leggings. You'll find these panels on the upper back, around the knees, and on the gusseted crotch. In theory, this should allow most of your lower extremities to retain heat and keep warm while also allowing much of your sweat to wick away quicker.

So does it work? We took these leggings with us on an intense fastpacking trip through the Sangre de Cristo Wilderness in Colorado to test this theory. Even at our fast pace, we never felt uncomfortably sweaty wearing these leggings, and we appreciated that we could stretch out how long we could wear them as the afternoon temps negated the need to have long underwear on at all. For those who perspire heavily and often — like our main tester — the BodyfitZone Merino 260 certainly stood out as one of our personal favorites.

icebreaker bodyfitzone merino 260 zone thermal leggings long underwear review - the thin fabric used in the gusseted crotch is one of the most...
The thin fabric used in the gusseted crotch is one of the most extreme we've seen, going almost all the way to the similar fabric that's used in the knees.
Credit: Maddock Rigby

Comfort and Fit

The soft and not at all itchy, almost 100% Merino wool is a favorite of ours and one of the main reasons to grab these leggings for yourself. A few carefully thought-out features help enhance comfort, including the back, gusseted crotch, and knees which help keep movement unimpeded and improve breathability to a high degree. Some other details of these leggings are more minimal, including the reasonably normal thickness of the top waistband and no-nonsense ankle cuff. A small amount of elastane has been added to the fabric to enhance stretch without being compressive.

Still, the fit is on the snug side and suits a more athletic profile above all else. The leg inseam on our size medium is around 30", as is the waist circumference — measurements similar to what we normally see and what fits our main tester, who usually wears a 32" inseam and waist for outerwear.

icebreaker bodyfitzone merino 260 zone thermal leggings long underwear review - knees of the icebreaker bodyfitzone are made of a thin wool panel...
Knees of the Icebreaker BodyfitZone are made of a thin wool panel that provides excellent articulation, but the fabric is more delicate.
Credit: Maddock Rigby


The Achilles heel of the BodyfitZone Merino 260 may actually be found in the knees. We'll gush on and on about the incredible breathability, especially while we're racing up the local hill in winter, but if you catch a toe on a tree root and take a tumble and scrape up your knees coming down, you may not get back to the trailhead without some rips and tears in these leggings.

The main problem seems to be that Icebreaker champions mostly Merino wool fabrics in its entire collection of base layers and uses very thin wool in the ventilation panels found in the back, crotch, and knees rather than a tougher synthetic. Our harsh abrasion tests have proven that Merino wool is a delicate material, even at heavier fabric weights. We may suggest even hand washing the BodyfitZone Merino 260 to protect your investment, and use them almost as race-day-only leggings. If you're looking for a breathable base layer to work through the winter framing houses while saving up before your summer thru-hike, look for a more durable pair of leggings.

icebreaker bodyfitzone merino 260 zone thermal leggings long underwear review - the main fabric above, compared to the more ventilated knee fabric...
The main fabric above, compared to the more ventilated knee fabric below the seam, shows the difference of these two materials.
Credit: Justin Simoni

Drying Speed

Top marks! Much like warmth, drying speed can usually be estimated by looking at both the material and the overall thickness of the fabric used. The BodyfitZone Merino 260 Leggings are made up mostly of Merino wool, with a small percentage of synthetic fibers built in to enhance elasticity. The weight of the majority of the fabric is approximately 150-200 g/m², except for those much thinner ventilation panels found in the back, the gusseted crotch, and around the knees - perhaps some of the thinnest materials we've seen used in any wool base layer. The more minimal waistband, when compared to others we've tested, also dries out a bit faster. Taken together, these leggings dry quickly and give some of the synthetics a run for their money. Drying speed can also loosely correlate with how fast sweat will evaporate off the garment when you're wearing it. Our experiences out in the backcountry seem to corroborate with the speed at which these bottoms dry out while we're on the go.

Much like all 100% Merino wool or Merino wool blend bottoms, we like to stress the importance of how you care for, wash, and dry these bottoms to maximize their lifespan. Hand washing may even be the way to go with these so that the more delicate ventilation panels don't succumb to the rips and tears of a top-load washer. Hang or flat drying is highly suggested — and the manufacturer even goes so far as to suggest drying them in the shade.

icebreaker bodyfitzone merino 260 zone thermal leggings long underwear review - dry time, as well as breathability, are some of the best in its class.
Dry time, as well as breathability, are some of the best in its class.
Credit: Justin Simoni

Layering Ability

The BodyfitZone Merino 260 works best as a next-to-skin dedicated base layer, and in that role, they absolutely excel. We wouldn't suggest these as your only bottom due to the delicate panels. The tight, athletic fit allows for excellent freedom of movement, and the generous ventilation panels mean you won't be sweating out underneath all your other layers. We had little problem mating these leggings with other mid and outer layers of various fabrics. Our favorite would be other tight, technical, and stretchy athleticwear, like running tights, that work well to continue to wick moisture from our bodies.

The weight of the BodyfitZone makes them best for cool to cold conditions; if you're planning on a really cold adventure for at least part of the time, it may be best to supplement these with another 150-200 g/m² base layer to enhance overall warmth.

icebreaker bodyfitzone merino 260 zone thermal leggings long underwear review - a snug fit and minimal seams make the icebreaker bodyfitzone layer...
A snug fit and minimal seams make the Icebreaker BodyfitZone layer well, especially with other tight fitting layers. The back panel is thinner, to increase breathability in a high perspiration area.
Credit: Maddock Rigby

Should You Buy the Icebreaker BodyfitZone Merino 260?

These leggings rate highly in breathability, drying speed, and layering ability but poorly in durability. If you can care for these properly to protect the upfront cost you'll incur at checkout, they're sure to perform well during your light and fast adventures, where the breathability of the ventilation panels will shine. If you're not planning to wear these performing feats of endurance in wintry conditions, perhaps consider a different pair that don't need such attention when caring for, washing, and drying.

What Other Long Underwear Should You Consider?

Although they run much warmer, the Smartwool Intraknit Thermal Merino 3/4 Bottom is also constructed of panels of fabrics with different traits to enhance performance metrics like breathability. We also found that these bottoms are much more durable due to the material being approx 50% Merino wool rather than almost 100%. If you don't need something quite so warm, look into the Artilect Boulder 125, which is an excellent warmer-weather legging that uses a thin Merino wool blend and panels of different fabric to enhance breathability. If the overall fabric weight of the BodyfitZone is mostly what you're looking for, but you don't need those ventilation panels, move laterally to Icebreaker's own Merino 200 Oasis Bottoms — they'll save you a bit of money at checkout, are warmer, and are more durable, while still having a similar fit.

Justin Simoni

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