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Arc'teryx Rho LT Bottoms Review

An outstanding synthetic bottom that offers great warmth, extreme comfort, a stellar fit, and durability to last; built for cold conditions these cozy bottoms are perfect for everything from winter trail running to cold resort skiing.
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Price:  $89 List | $79.00 at Amazon
Pros:  Warm, super comfy, durable, great fit, versatile, don’t stretch out
Cons:  Pricey
Manufacturer:   Arc'teryx
By Roland Mott ⋅ Review Editor  ⋅  Dec 20, 2018
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75
OVERALL
SCORE


RANKED
#1 of 8
  • Warmth - 30% 7
  • Breathability - 30% 6
  • Comfort and Fit - 30% 9
  • Durability - 10% 9

Our Verdict

The Arc'teryx Rho LT was an instant favorite among testers and staff. It's supremely comfortable; the brushed fleece interior is the coziest next to skin feel of any bottom we tested. The polyester/elastane blend offers the most durable fabric we tested and is extremely stretchy. Even though it's advertised as LT or lightweight it is one of the warmest bottoms we tested, second to the SmartWool Merino 250. Versatile and comfortable for all-day wear, it's a perfect all around pant for cool to cold seasons and the only pant that is handsome and inconspicuous enough to wear as an outer layer, like a running tight. With a superb fit, super comfy fleece-lined fabric, terrific quality, great functionality, and solid warmth, the Rho LT was a tight contender for the Editors' Choice Award. The reason that it didn't win the award is the merino Outdoor Research Alpine Onset's superior ability to thermoregulate, breathe and wick away sweat. Read on to learn about this all-star bottom!


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Awards  Editors' Choice Award Top Pick Award   
Price $79.00 at Amazon$61.73 at REI
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$95.00 at Amazon
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$55.93 at REI
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$79.50 at REI
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Pros Warm, super comfy, durable, great fit, versatile, don’t stretch outWarm, lightweight, great breathability, versatile, quick to dry, anti-odor, great fitExtremely warm, super cozy, terrific temp regulation, breathableWarm, lightweight, breathable, versatile, comfortable, great thermoregulationComfy, warm, simple, breathable
Cons PriceyNot super durable, not for super coldStretches out, soggy crotch, slow to dry, expensiveNot very durableNot very durable, tend to stretch
Bottom Line An outstanding synthetic bottom that offers great warmth, extreme comfort, a stellar fit, and durability to last; built for cold conditions these cozy bottoms are perfect for everything from winter trail running to cold resort skiing.A go-to, do-it-all merino base layer that provides superb insulation, incredible breathability, and a dialed-in fit for high performance in any situation you can dream up.An extremely warm and breathable pair of bottoms built to keep you warm in the coldest conditions but versatile enough to carry into seasons outside of winter.A fantastic pair of lightweight merino bottoms that provide impressive warmth without being too hot, breathe extremely well and are very comfortable.A simple and comfortable merino option
Rating Categories Arc'teryx Rho LT Bottoms Alpine Onset Bottoms SmartWool Merino 250 Bottoms SmartWool Merino 150 Bottoms Merino Midweight Bottoms
Warmth (30%)
10
0
7
10
0
6
10
0
9
10
0
6
10
0
6
Breathability (30%)
10
0
6
10
0
8
10
0
7
10
0
8
10
0
7
Comfort And Fit (30%)
10
0
9
10
0
9
10
0
6
10
0
7
10
0
7
Durability (10%)
10
0
9
10
0
6
10
0
8
10
0
5
10
0
6
Specs Arc'teryx Rho LT... Alpine Onset Bottoms SmartWool Merino... SmartWool Merino... Merino Midweight...
Material Torrent (84% polyester, 16% elastane) 83% merino wool, 12% nylon, 5% spandex 100% merino 87% Merino Wool, 13% Nylon Core Ultra-fine 200g merino wool
Weight (size S) 5.57 oz 4.80 oz 7.55 oz 4.94 oz 5.93 oz
Fabric Weight Not listed Not listed 250g 150g 200g
Fabric weights and other versions available Boot-cut Lightweight Lightweight, midweight 150, 250 Midweight
Fly? No Yes Yes Yes Yes
Dryer safe? Yes Yes Yes Yes Yes

Our Analysis and Test Results

A comfortable, warm, and versatile bottom that delivers reliability and our favorite fit, the Arc'teryx Rho LT is at home in cold alpine conditions, shoveling the driveway, and enjoying a good book on your rest day at the lodge all the same.

Performance Comparison


Swinging for the fences in Ouray Ice Park  Colorado
Swinging for the fences in Ouray Ice Park, Colorado

Warmth


These are advertised as LT or lightweight but pack a punch for warmth. The 150-gram weight synthetic Torrent fleece is slightly thicker than a traditional merino midweight like the Outdoor Research Alpine Onset but supply slightly more warmth. The brushed fleece interior is warm and super cozy next to skin. These are our go-to bottoms for low output activities in cold weather like resort skiing or winter camping.

Stepping outside to gather wood to stoke the stove on a hut trip in the Wasatch
Stepping outside to gather wood to stoke the stove on a hut trip in the Wasatch

Warm enough to be our only layer underneath a pair of non-insulated ski pants. Advertised as a lightweight, we wouldn't suggest these for lightweight use as you'll end up hot and sweaty. These bottoms offered the most warmth next to the ultra-thick and cush SmartWool Merino 250.

Bad photo  rough conditions  warm legs! RHO LT are great for long days out in the cold.
Bad photo, rough conditions, warm legs! RHO LT are great for long days out in the cold.

Breathability


For a thicker synthetic layer, these breathe impressively well. The Torrent fleece does a wonderful job of wicking sweat to the outside of the fabric and drying quickly. They do tend to hold onto water once moisture settles into the fibers though as we experienced in our drying test. We put the breathability of these pups to the test trail running in the mountains overlooking Salt Lake City with temps varying from the 40s down to single digits. These tights did a great job balancing warmth and keeping us dry. Hill sprints in 40-degree weather were the upper limit of warmth and output for these; they weren't able to breathe as fast as we were creating perspiration in that warm of a climate, so held onto some moisture but dried quickly once I rested. Running in colder weather they did a terrific job of staying warm and breathing well. If these were more breathable and wicked sweat better, they'd be unstoppable. For a pair of bottoms that are much more breathable and offer similar warmth, check out the Outdoor Research Alpine Onset.

Testing breathability on a cold trail run above Salt Lake City.
Testing breathability on a cold trail run above Salt Lake City.

Comfort & Fit


Ooooh, are we excited to tell you about the comfort and fit on these! One word - Superb! An extremely stretchy but tight and comfortable fit paired with a purposeful design and sleek look earn our favorite fit for these bottoms. They wear like a second layer of skin, glued to you. Not the easiest to pull on, they are snug and the fleece lining is sticky but once they're on, it's like they were laser molded to your bottom half. The close fit and stretch allow them to move freely with you and the synthetic fabric wears well all day and use after use, not stretching out like a typical merino layer.

Technical seam pattern and super stretchy fabric allows for maximum mobility
Technical seam pattern and super stretchy fabric allows for maximum mobility

The synthetic fabric is 84% polyester/16% elastane utilizing Arc'teryx Torrent fleece has a sleek and smooth outer fabric that slides easily inside of a layer and an ultra-cozy soft brushed fleece lining that feels like heaven next to your skin. The waistband is comfortable and simple, there is no crotch sag, and a simple and technical seam pattern incorporates a gusseted crotch that runs on the inseam down to the knees for ultimate mobility. These are the only bottoms that don't offer a fly, so you'll be pulling these bad boys down for backcountry relief. The lack of a fly is our only qualm with these nearly perfect fitting bottoms.

The fit of the Rho LT bottoms from Arc'teryx.
The fit of the Rho LT bottoms from Arc'teryx.

Durability


Another category winner, the Rho LT proved themselves as the most durable bottom we tested. Made of a thicker synthetic material, they showed some surface wear in our brutal and merciless abrasion test that is notorious for blazing holes through base layer fabrics. Synthetic fabrics are generally more durable than fragile merino, so all of the synthetic bottoms that we tested did well in the durability category. These bottoms aren't cheap but they will serve you for years of hard use. We wouldn't suggest walking through a briar patch or a barbed wire fence wearing these, but we wouldn't recommend that in most circumstances. For extreme warmth and good durability but with the benefits of merino check out the SmartWool 250 Merino bottoms.

Lacing up for a winter trail run. The excellent durability  ultra-comfortable fabric  and handsome look made these not only a great base layer for cold weather skiing but our go-to for winter trail running.
Lacing up for a winter trail run. The excellent durability, ultra-comfortable fabric, and handsome look made these not only a great base layer for cold weather skiing but our go-to for winter trail running.

Best Applications


These bottoms are best used for low cardio activity in cool to cold conditions. We found that we loved them as a stand-alone layer for trail running in the winter and resort skiing, but these bottoms are versatile and will keep you company and serve you well in most endeavors except super warm weather and crazy high output activities like spring backcountry skiing.

Our go-to cold weather trail running pant
Our go-to cold weather trail running pant

Value


At $89 these are tied with the Outdoor Research Alpine Onset bottoms for the second most expensive bottom that we tested. Although these are a pricey pair of bottoms, we feel with these in particular, you get what you pay for - which is a quality and versatile pair of bottoms that are going to serve you for years of use and abuse.

The low profile zipper pocket is convenient to carry a credit card or chapstick along. Paired with the handsome look of the bottoms  they are the only ones that can be pulled off as a running tight and worn as a stand-alone layer in public.
The low profile zipper pocket is convenient to carry a credit card or chapstick along. Paired with the handsome look of the bottoms, they are the only ones that can be pulled off as a running tight and worn as a stand-alone layer in public.

Conclusion


We are in love with these bottoms for cold season endeavors. Their comfort, fit, quality, and versatility to perform well in varying activities and temps get two thumbs up from us. A thoughtful and handsome design, these are the only bottoms we felt comfortable wearing as a stand-alone layer for trail running. A great pair of bottoms if you need a durable pair of bottoms for venturing out into cold temps and appreciate quality and extreme comfort.


Roland Mott