Black Diamond Long Sleeve Rhythm t-shirt review: for unstoppable adventurers

This fast-drying, ultra-light top is priced for pros but makes the consummate companion for trail running in cooler weather – and a flawless first layer for other outdoor pursuits

Black Diamond LS rhythm tee women's
(Image: © Black Diamond)

Advnture Verdict

This ultra-lightweight, fast-drying top combines natural and synthetic fabric so it breathes better, dries fast and moves with you, making it a staple for any adventurer’s outdoor kit.


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    Ultra lightweight

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    Pricey for the casual skier

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    Wide neck may not be as warm for some conditions

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    No thumb holes

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Black Diamond Long Sleeve Rhythm t-shirt: first impressions

Black Diamond claim their Long Sleeve Rhythm T-shirt is the world’s lightest ultimate high output, breathable layer and weighing in at just 104 grams, they can’t be too far off. This high quality base layer comes in a classic design but is made using Nuyarn merino wool technology which is touted as lighter, faster drying and 35% more stretchy than standard merino.

Sure enough, this soft, featherlight top is designed for movement, with a slim-but-not-tight fit, underarm panels to aid movement and a wide crew neck. It’s thin enough to fit under any mid layer in colder weather, makes the perfect breathable trail running top for when you’re covering a lot of ground in cooler temperatures and looks and works great for everyday use too. It holds up to a lot of action without needing to be washed after every adventure, so though it comes at a premium price, you’ll barely take it off once you pull it on.


• RRP: $110 / £80
• Sizes available: XS-XL
• Unisex: Men’s and women’s specific fit available
• Materials: Wool Nylon Blend Single Jersey (57% Nylon, 43% Merino Wool, 95gsm)
• Colors: Black, Pewter
• Weight: 104 g / 3.6 oz
• Best use: Trail running, hiking, camping, skiing, snowshoeing 

Black Diamond Long Sleeve Rhythm t-shirt: on the slopes

Black Diamond LS rhythm tee

Every few years, a base layer comes along that relegates all other base layers to the bottom of the pile (Image credit: Black Diamond)

Every few years, a base layer comes along that relegates all other base layers to the bottom of the pile for me. It’s either on my body, or folded at the very top of the drawer waiting to be worn out on my next adventure. The Black Diamond Long Sleeve Rhythm t-shirt definitely fits that bill for me and has honestly barely come off since it arrived.

I’ve worn this shirt on multiple hikes, trail runs, on my yoga mat and around the house. It’s soft and so lightweight I can barely feel it, and the classic fit isn’t too tight which, combined with good stretch, means I can move in any way I want without it catching or rubbing anywhere. I find the fit flattering enough that I frequently wear it with jeans around town, but it is slim enough that I can easily layer it under my fleece or down jacket, and it's long enough to comfortably tuck in.

For trail running, it definitely keeps me cool once I’m a few miles in and I couldn’t help but notice how quickly it dries. Rather than change as soon as I get back to the car like I do with my all-synthetic tops, this one stays on comfortably for the drive home. Because it’s made using natural materials, it can also hold up to quite a few hikes before it needs a wash, which is always a winner in my book.

The wide neck is really flattering and comfortable, however I think on a colder day I might opt for a top with a high zipped neck for snowshoeing if it was likely to be my only layer on the uphill, and it’s certainly on the pricey end of the spectrum, but for how versatile and durable it is, I think I’m getting my money’s worth on this one.

Here’s how it performed:


True to size.


It’s not a skin tight top, but a flattering slim fit. Long enough to tuck in with a wide crew neck.


Soft, barely there feel to the fabric with added arm and underarm panels to support movement and no rubbing seams.

Temperature regulation 

Keeps you warm as a first layer in colder weather and keeps you cool once you start sweating on a trail run.


Ultra breathable, this shirt keeps you drier on the trail and dries quicker once you get back to the car or camp.


So far, it’s standing up to the test of my adventures. The nylon/merino blends adds some stamina. Like any high end piece of gear, I recommend washing it on gentle, less frequently, and line drying to make it last longer.

Here’s where we tested the Black Diamond Long Sleeve Rhythm t-shirt:

From many high points in Glasgow, you can see the distinctive hill of Dumgoyne which is technically at the beginning of the Highlands. This volcanic plug makes a short but very steep hike on its own, or you can pair it with Earl’s Seat to the north for a longer hike or trail run.

Julia Clarke

Julia Clarke is a staff writer for and the author of the book Restorative Yoga for Beginners. She loves to explore mountains on foot, bike, skis and belay and then recover on the the yoga mat. Julia graduated with a degree in journalism in 2004 and spent eight years working as a radio presenter in Kansas City, Vermont, Boston and New York City before discovering the joys of the Rocky Mountains. She then detoured west to Colorado and enjoyed 11 years teaching yoga in Vail before returning to her hometown of Glasgow, Scotland in 2020 to focus on family and writing.