When you combine an optimized synthetic layer with Merino wool where odor management matters, you get the Arc’teryx RHO Hybrid Crew Neck long-sleeve base layer. This combo has been excellent in all regards as a base layer for winter trail running.
Arc’teryx RHO Hybrid Crew Features:
- Phasic™ AR II material mixed with Merino wool underarms
- Micro-grid backing accelerates moisture transfer
- Form-fitting design for base layer performance
- Merrow stitch seam construction reduces bulk
- Crafted at a Fair Trade Certified facility
- MSRP: $115

Phasic and Merino: Like PB&J
Midweight long-sleeve layers can be pretty versatile. As a base layer, the added warmth is typically welcome. And, as an outer layer, the same sentiment applies. Throughout the endless 2022-2023 Utah winter, I’ve employed a variety of jackets, base layers and mid layers to face the cold and snowy conditions. I consider myself pretty hardy, but my mettle was tested and the Arc’teryx RHO Hybrid Crew has been a great companion for trail running and hiking.
Unlike the Arc’teryx Motus AR Hoody, the RHO Hybrid Crew lacks a hood (of course), but it also utilizes Merino wool underarm inserts to get the benefits of both the synthetic and natural fibers. My love affair with Merino wool is well-documented, but I was anxious to test out the deliberate placement of it on this shirt.

The bulk of the shirt is made from Phasic AR II fabric, which features a smooth face and micro-grid interior. As expected, it is cozy next-to-skin and provides instant warmth without feeling too hot. I could comfortably wear it for indoor core and strength training sessions, as well as a wide variety of winter trail running and hiking.
During activity, the shirt moves with me. I didn’t experience any chafing or other similar issues. That’s partly due to the nature of the fabric, but also the construction. Flat seams are always preferred and Arc’teryx calls it “merrow” stitching. Either way, it always prevents seam discomfort and chafing.

The million-dollar question is just how well do the Merino inserts deliver odor-free performance? My answer is pretty darn good. Granted, it’s not as adept as a full Merino shirt, but it also retains its shape much better overall due to the Phasic AR II fabric. In the end, it’s a win-win as the RHO Hybrid Crew breathes well and stays stink-free after multiple uses. After a run, it does dry pretty quickly, but don’t expect it to dry at the snap of your fingers. The sleeve and hem lengths provide good coverage.
Fit: I’m 5’11” and 175 lbs, wearing the size medium. It’s a good fit for active use, but a large might be better for less active pursuits.
The Good
- Phasic II material is cozy and extremely breathable
- Flat stitching FTW
- Merino inserts extend wearability
- Great as both a base layer and outer layer (depending on temperatures)
- Pretty much the best of of both natural and Merino performance
The Bad
- Hard to find at retail
The Bottom Line: Arc’teryx RHO Hybrid Crew
If you can find the RHO Hybrid Crew at retail, I’d give you the green light to pick one up. The fabric stretches nicely and maintains its structure better than full Merino shirts. I have appreciated it as a base layer and an outer layer alone, or with a vest for trail running from 20 to 60 degrees.
Buy Now: Available from Arc’teryx