Arc'teryx Rho Bottom - Women's Review

Thanks to their high-performing and minimalist design, the Arc'teryx Rho is one of our favorite pairs of long underwear bottoms. The next-to-skin fit is flattering and functional when considering the warmth these lightweight bottoms offer, whether worn alone or within a layered system. We love the high-rise waistband and stash pocket on the thigh, especially when out for a long run or Nordic ski. We're confident these leggings will impress you with their versatility, whether doing yoga or skinning uphill in the backcountry.

Performance Comparison

Warmth

While the Rho is not designed to provide warmth for the coldest months of the year, our testers love the ample warmth it has when worn as a stand-alone piece during spring and fall training runs, in addition to the effective warmth when layered below additional ski bibs and puffy pants during winter. Arc'teryx recommends these bottoms for cool to cold weather, and we would agree.

During our extensive testing period, we recorded the temperature ranges where these bottoms provided enough warmth to remain comfortable. We found the sweet spot to be somewhere between 30-50 degrees Fahrenheit, depending upon the conditions. They were even comfortable down to the teens while backcountry skiing with ski bibs layered over the top. Anything above 60 degrees in these bottoms, and you'll wanna dial back the intensity. Overall, we were impressed with the lightweight and slim-fitting synthetic design that enhances the thermal efficiency of these long underwear bottoms.

Breathability

The 84% polyester and 16% elastane material, combined with the Torrent stretch fleece and Polygiene treatment, help to manage moisture generated during activity. The fabric truly wicks moisture away from the body and allows the vapors to escape when exposed to fresh air. We love that the fabric is thick enough to be worn on its own yet remains lightweight and porous enough for airflow to penetrate the synthetic fibers.

During our testing period, we noticed that though the waistband is very minimal and low profile, this is often the spot where sweat would pool. This is likely because that's the area often covered up with another layer or a heavy backpack, thereby preventing any fresh air from aiding in breathability. Overall, we gave the Rho high marks for its effective moisture management capabilities.

Comfort and Fit

The Rho has one of the most functional fits we've tested, perfect for a wide variety of activities. The design is minimal and next-to-skin, yet includes very thoughtful details such as an elastane fabric that is brushed for softness and allows for stretchy comfort. The first time we tried on these bottoms, they almost felt compressive, though, over time, they stretched enough to increase comfort without losing any support.

The fit in the Rho is true to size, yet slim, so it's perhaps best to size up if you find yourself in between sizes. We love the thick and high-rise waistband that is both flattering and functional, as these bottoms never required adjusting, whether we were backcountry skiing, trail running, or doing yoga. The design also features a gusseted crotch and articulated patterning, which we found to aid in a full range of motion and increased mobility. We highly recommend the Rho if you're after a versatile bottom with exceptional comfort and stretch performance — it even has a stash pocket for energy gels, bars, or a smartphone.

Durability

While we haven't experienced any major durability with the Rho bottoms, we don't recommend them for activities like rock climbing or trail running through technical rocky terrain. The polyester fabric is incredibly durable, especially considering its lightweight construction, but we could imagine it being prone to rips or snags when encountering sharp rock. This is not a bottom we'd recommend for off-trail, either. We consider these bottoms more of a versatile base layer rather than tights or yoga pants, but we're psyched that they perform both inside and outside of our ski bibs. The merrow stitch and flatlock seams effectively hold the layer in place, but we did notice a bit of fuzz on top of the seams after layering beneath our bibs.

Though Arc'teryx really boasts about its odor-resistant Torrent fabric with Polygiene treatment for long-lasting odor control, we experienced quite the opposite. After a couple months of testing, we found that these bottoms really hang onto odor post activity. This is true of most polyester synthetic bottoms though, and we found that it wasn't noticeable enough for partners to complain. If odor-free construction is what you're after, we'd recommend a Merino wool option for better performance.

Drying Speed

When considering drying speed for base layers, we wanted to simulate what it's like to wash and dry the layers while on an extended backcountry trip. We soaked, wrung out, and hung the Rho on a line to dry before recording the speed. These leggings dried in a speedy 43 minutes on the line.

We really enjoyed the Rho while on training runs in the spring, so after an hour of intense movement, we started our timer to record their drying speed on the body. While results varied, it often took around 40 minutes to dry completely, usually taking the longest time around the waistband. We attribute this performance to a quick drying and moisture-wicking polyester/elastane combination.

Layering Ability

The Rho is surprisingly easy to layer thanks to its minimalist design. The next-to-skin fit makes for easy layering over the top, and the high-rise fit allows for additional layers to fasten at the natural waistline with minimal bulk.

While we love the addition of the stash pocket on the thigh, we found that it was best not to use this pocket with our ski bibs layered over the top because it was in the same location as our beacon pocket. As you might imagine, using both pockets in the same location was pretty bulky and distracting while skinning uphill.

Should You Buy the Arc'teryx Rho Bottoms?

If you're after a lightweight synthetic pair of long underwear bottoms that can really do it all, the Rho is a great choice. The minimalist design features thoughtful patterning and a flattering and functional fit that increases comfort and thermoregulation. Though a little more of an investment, we're confident you'll be impressed with these bottoms, whether worn on their own or within a layered system.

What Other Long Underwear Should You Consider?

If you are interested in a synthetic long underwear bottom with a more stripped-down design, check out the Patagonia Capilene Midweight Bottom. The Midweight offers a ton of durability and is our lead tester's favorite overall workhorse when it comes to year-round use. If breathability is more important than versatility, but you don't want to sacrifice synthetic comfort and fit, check out the Patagonia Capilene Thermal Weight. If you want to throw down for the very best Merino wool option that we've tested, consider investing in the Icebreaker 200 ZoneKnit Merino Leggings. These high-waisted bottoms offer high performance in breathability and year-round warmth without retaining any odor from your efforts. And if you're curious about what a Merino wool and synthetic blend is all about, check out the Smartwool Intraknit Thermal Merino Bottom. These bottoms are a better choice for super cold weather and can be worn on their own or below your ski bibs.