Smartwool Intraknit Thermal Merino Bottom - Women's Review
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|Price||$62.50 at Backcountry|
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|Pros||Awesome breathability and thermoregulation, highly functional waistband, great mid rise fit, articulated design increases mobility||Supersoft Polartec fabric, superior breathability, excellent warmth, great fit that enhances mobility, recycled fabric||Excellent warmth, soft elastic waistband, odor-free, high waisted design for additional coverage||Lightweight, versatile, ample warmth, great fit and waistband, soft synthetic fabric, thigh pocket||Smooth and silky fabric, easy to wear alone or when layered, cute and fitted style, affordable|
|Cons||Expensive, longer drying speed, thicker waistband creates bulk when layered, performance fabric lacks comfort||Questionable durability, fabric holds odor||Thicker fabric doesn't breathe as well in warm climates, fabric shows signs of wear after minimal use, longer drying speed||Pricey, merrow seams accumulate fuzz from friction||Absorbs and holds moisture, fabric retains odor immediately|
|Bottom Line||These high performing midweight bottoms maximize warmth through strategic ventilation for optimal moisture management during cold weather conditions||A high-performing long underwear bottom that traps a ton of warmth while releasing any excessive moisture created during cool to cold weather activity||These heavyweight 100% Merino wool bottoms offer superior warmth and comfort at a fraction of the cost||This lightweight synthetic long underwear bottom can do it all, thick enough to perform on its own or within your cold weather kit||This synthetic base layer option features a soft and stretchy polyester fabric that offers moderate levels of warmth and breathability for an affordable price|
|Rating Categories||Smartwool Intraknit...||Patagonia Capilene...||Ridge Merino Invers...||Arc'teryx Rho Light...||REI Co-op Midweight...|
|Comfort and Fit (20%)|
|Drying Speed (10%)|
|Layering Ability (10%)|
|Specs||Smartwool Intraknit...||Patagonia Capilene...||Ridge Merino Invers...||Arc'teryx Rho Light...||REI Co-op Midweight...|
|Material||52% Merino Wool, 45% Polyester, 2% Elastane, 1% Polyamide.||92% recycled polyester, 8% spandex||100% Merino wool||84% polyester, 16% elastane||92% polyester, 8% spandex|
|Fabric Weight (g/m²)||Not disclosed||129 g/m²||270 g/m²||190 g/m²||Not disclosed|
|Measured Weight (size small)||8.32 oz||4.90 oz||7.36 oz||4.80 oz||6.40 oz|
|Cuts Avaliable||Full length||Full length, boot length||Full length||Full length||Full length|
|Smelly Over Time?||No||Yes||No||Yes||Yes|
|Odor Control Fabric||Merino yes, polyester no||HeiQ Fresh||Naturally odor resistant||Yes, Torrent||N/A|
Our Analysis and Test Results
The Intraknit Thermal stands apart from the other long underwear bottoms in this review due to a modern design with gender-specific body mapping for enhanced warmth and ventilation. Unlike other midweight bottoms that provide warmth but retain moisture during activity, these bottoms keep you warm by offloading sweat. Whether worn on their own or layered below your ski bibs, these thicker bottoms will keep you comfortably warm and dry no matter what winter activity you have planned.
Smartwool really nailed a niche category by adding articulated patterning and ventilation panels into a midweight design. The intelligent Intraknit technology efficiently regulates body temperature by offloading excess moisture to trap and maintain the body heat generated during rigorous activity. Unlike most mid and heavyweight options in this review that retain moisture, these tights are highly functional at thermoregulation.
During our testing period, we hit the trails, skin track, and dry roads in temperatures ranging from 15-55 degrees Fahrenheit. We were impressed with the warmth these bottoms offered without causing us to feel overheated or cold from sweat. Any temperatures below 10 degrees (depending on humidity) and we would have been more comfortable with another layer over the top, but really we were surprised with how well the Intraknit can retain body heat. Likewise, the same ventilation panels successfully released warmth in temperatures above 55 degrees. If you're looking for a cold weather long underwear bottom that offers a ton of warmth without sacrificing moisture management, these are a great option.
While we were initially skeptical, the Intraknit proved us wrong repeatedly. To measure the overall breathability of these bottoms, we hit the trails, sprinted on dry roads, and got moving on the skin track. Throughout each activity with varying weather patterns, these bottoms successfully wicked moisture away from the body and released it through the fabric.
These are some of the thickest bottoms that we tested, but the ventilation panels help set them apart from the rest, amplifying cold weather insulation while also managing moisture. If we have any complaints, it's the thicker waistband, which is hard to complain about because it does such a great job of providing structure and holding these bottoms in place, but if sweat is gonna pool anywhere, it's here. Overall the breathability of the ventilation panels improves the design, making these bottoms perfect for high-output activities like backcountry skiing and trail running.
Comfort and Fit
While we absolutely love the fit, especially the mid-rise 2" waistband that hugs the curves and provides some structure to the Merino sport yarn fabric, we had to dock these tights a few points for minimized comfort. The Merino sport yarn and polyester blended material add a ton of value to these tights but, unfortunately, sacrifices that next-to-skin Merino wool comfort — we found the fabric to be itchy at times.
The fit is a different story. The Intraknit truly offers extraordinary fit due to its integrated body mapping technology with minimal use of flatlock seams. The full-length fit is true to size, and perhaps our only complaint is that the articulated knees sit just above our actual knee when wearing a size small on our 5'6" frame. We love the increased range of motion we can achieve with this thoughtful fit, in addition to the ventilation panels that increase comfort by keeping us dry; we just wish we didn't have to give up that super soft next-to-skin comfort we've grown accustomed to with Merino wool.
We're happy to report that we've experienced no durability issues with these tights, even after taking an unexpected digger while running fast through some technical terrain in the desert. Smartwool really increased the durability of the Merino sport yarn by adding polyester, which helps give some structure to these wool tights.
If you want to extend the life of these high-quality long underwear bottoms, we recommend following the care instructions and washing them in a machine on a gentle cycle, and laying them flat to dry. This will prevent any damage from the heat of the dryer or unwanted stretch from drying on a hanger.
It was important to our testers to consider the drying speed of each layer while simulating what it would be like to wash and dry the layer during an extended trip in the backcountry. As expected, due to the thicker, heavier material, the Intraknit also required more time to dry at 65 minutes.
We found that the drying speed increased by more than double when the layer could utilize body heat generated during high output activity such as runs and skinning uphill. In those circumstances, these bottoms dried as quickly as 25 minutes on the body. Not a stellar performance here, but considering these weigh 8.32 ounces and offer stellar warmth and thermoregulation, not too bad either.
Unfortunately, we found these tights to be a little tricky to layer due to a very slim fit. The Merino/polyester blended fabric can get a little grabby with things like ski bibs or pants unless those layers offer a smooth fabric interface. This resulted in some friction that was noticed during our uphill skin track testing drills.
The thicker fabric of the bottoms and the wide 2" waistband can also reduce the space you might normally be accustomed to inside your ski bibs. That said, we love that the Intraknit can easily be worn as a stand-alone piece, in addition to easy layering with rain and puffy pants that feature a smooth fabric to interface with.
Should You Buy the Smartwool Intraknit Thermal Merino?
These high-performing bottoms are worth every penny. For those looking for a versatile cold-weather bottom that amplifies thermoregulation and breathability through strategically placed ventilation panels, whether worn on their own or layered within a system, the Intraknit put a modern twist on midweight insulation.
What Other Long Underwear Should You Consider?
If you dig some versatility but prefer a stash pocket for gels, keys, or your smartphone, and don't mind a lightweight construction, check out our favorite bottoms for multi-sport performance, the Arc'teryx Rho Lightweight Bottom. If you want to save a little money and don't need all the bells and whistles, the Ridge Merino Inversion Heavyweight Merino Leggings provide a ton of warmth at a fraction of the cost.
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