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Black Diamond Rhythm Tee Review

A go-to running shirt or baselayer for day after day use with little to no signs of wear
Top Pick Award
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Price:  $75 List | $74.95 at Backcountry
Pros:  Great mobility, durable, soft and comfortable, good odor-protection
Cons:  Minimal reflective banding, pricy
Manufacturer:   Black Diamond Equipment
By Jeff Colt ⋅ Review Editor  ⋅  Jun 2, 2020
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84
OVERALL
SCORE


RANKED
#2 of 10
  • Comfort - 30% 9
  • Breathability - 30% 9
  • Drying Speed - 20% 7
  • Features & Versatility - 20% 8

Our Verdict

The Black Diamond Rhythm Tee is an excellent running shirt and base layer. The merino wool/nylon blend is soft on the skin and stretches superbly, allowing it to move with your body. It's also breathable, lightweight, and retains little to no odor. We wore it day in and day out, under parkas and packs, and it performed phenomenally, retaining its shape despite the fabric's stretch. This is an incredible base layer, making it a natural choice for a Top Pick Award. The marriage of stretch, breathability, and comfort led us to pull it on in the morning and leave it on all day, regardless of activity. Use as a nighty, wake up, adventure, repeat.

Compare to Similar Products

Our Analysis and Test Results

Black Diamond set out to make the lightest running shirt possible with the benefits of merino wool. At 3.3 ounces, the Rhythm Tee is wonderfully light, very breathable, and our Top Pick for Layering. While the price is steep, this piece offers more than most running shirts in the form of merino wool benefits. A simple construction paired with amazing stretch creates a layer that doesn't chafe with a pack or layers, has no excessive stitching (thus reducing weight and increasing durability), and breathes well while wicking moisture. It could use some added reflective banding, but other than that it's simply stellar.

Performance Comparison


So light and stretchy  it flows effortlessly with body movements. An excellent shirt for running or anything that will utilize the benefits of the merino wool fabric as a highly breathable base layer.
So light and stretchy, it flows effortlessly with body movements. An excellent shirt for running or anything that will utilize the benefits of the merino wool fabric as a highly breathable base layer.

Comfort


The Rhythm Tee topped the charts in overall comfort, both when pulling it on for the first time and when performing on the trail. Unlike some merino wool shirts, there is no itch or discomfort against the skin here. At 3.3 ounces, the lofty fabric feels almost cloudlike and is barely noticeable.


It can't be said enough; the stretch and shape retention of this shirt are ridiculous. While our tester, at 5'10" and 155lb, wore a medium, he likely could have comfortably worn a small or large. Smooth and soft flatlock seams stretch with the merino wool/ nylon fabric, and however perplexing it may be, the shirt kept its form. Even the soft thread used on the flatlock seams contributed to the four directional stretch. Outperforming many shirts with body mapped mesh panels and underarm gussets, this tee has a very simple design with side seams and raglan sleeves connecting to the collar. Fewer seams, paired with the qualities of the Nuyarn fabric, make for a more comfortable and durable ride by eliminating weak points.

Talk about stretch! One of the factors that makes the Black Diamond Rhythm Tee a Top Pick is the form  fit  and function that the wildly stretchy merino wool/nylon blend offers.
Talk about stretch! One of the factors that makes the Black Diamond Rhythm Tee a Top Pick is the form, fit, and function that the wildly stretchy merino wool/nylon blend offers.

While we worried that the stretch of the Rhythm Tee might cause bunching, and shape retention made us think of discomfort and bunching, it fit comfortably beneath a light windbreaker, fleece hoody and three layer shell. The highly breathable fabric with its natural wicking properties led us to ditch our normal long underwear. As the lifts stopped spinning in the spring, we lived in this shirt for spring ski missions, often leaving the house on a bike, skinning for hours, ripping down our objective, and biking home.

For the most expensive shirt in the review  underarm gussets seem like a no-brainer  but the merino wool/nylon blend is so stretchy  an underarm gusset would only add unnecessary seams. The comfort is all there.
For the most expensive shirt in the review, underarm gussets seem like a no-brainer, but the merino wool/nylon blend is so stretchy, an underarm gusset would only add unnecessary seams. The comfort is all there.

Breathability


There are shirts that feature strategic mesh paneling to promote ventilation, and there are shirts that use a uniform polyester blend to capitalize on evaporative cooling. This shirt does not fall into either of these categories. The Rhythm Tee is made with Nuyarn, a fabric that uses merino wool drafted over a synthetic nylon core. On the outside of the fiber is merino wool, an excellent wicking agent, while on the inside is highly stretchable nylon. This makes the entire shirt permeable to airflow and equips it with the thermoregulating benefits of merino wool.


If you have enjoyed the breathability of other merino wool shirts but felt uncertain about the comfort or durability, this shirt may change your mind. During hill repeats in the heat, it wicked moisture and promoted evaporative cooling. And, while nordic skiing on the spring crust in Ashcroft, CO, it retained enough body heat to keep our testers warm while not sweating through. The best of both worlds.

As you see  air can pass easily through the fibers of the shirt  heightening breathability.
As you see, air can pass easily through the fibers of the shirt, heightening breathability.

Drying Speed


Our standardized drying speed test helped us compare polyester shirts surprisingly well, but it didn't take into account the feel of the damp material against the skin. While the Rhythm Tee did not exhibit the same drying capabilities as some of the polyester shirts in the mix, on the trails, it performed phenomenally.


When wet, this shirt held 63% of its weight in water. After the first spin cycle, it retained 30% of its weight in water, and after ten minutes in the dryer, only 9% of the shirts weight in moisture remained. The notable difference here is that at 9%, it felt completely dry to the touch, while polyester shirts feel damp with between 2%- 5% of their weight in water remaining.

Outside of our kitchen lab test, we never reached a point of discomfort while wearing the Rhythm. We did note, however, that when properly wet from a spring rainstorm, the fibers stretched out, and the shirt got larger — though it returned to its normal shape and size as it dried. When wet and stretched out, the fibers were more susceptible to degradation. Since wool is a natural fiber and not a plastic, we tried to avoid direct friction between pack and shirt when it was wet.


Features & Versatility


This is one versatile base layer, so much so that it performs phenomenally as a running shirt. We wore it during both hot yoga and freezing dawn patrol missions, and it crushed. For 50 kilometer races and track workouts, same deal. From rock climbing to mountain biking, the comfort and performance of the Rhythm Tee rang true. It is a highly effective base layer for all seasons.


With a tag-less neck and an integrated collar sweatband that stretches with the shirt, comfort was spared at no cost. Sadly, though, the Rhythm Tee doesn't boast UPF protection and only features two small reflective logos, a critical feature that could make this highly versatile shirt a great choice for urban commuters. Nonetheless, the primary features of this shirt remain in the fabric.

Black Diamond's reflective logos on the Rhythm Tee are on the front and back of the shirt. Despite being minimal  they still offer a glint of reflection.
Black Diamond's reflective logos on the Rhythm Tee are on the front and back of the shirt. Despite being minimal, they still offer a glint of reflection.

We couldn't smell a hint of our efforts on this versatile shirt. It felt like forgetting to record a run on Strava. Week after week, there was nothing to show or smell. The odor-control benefits of merino wool are striking. We sniffed for odors while exercising in the shirt, after workouts, and after it had been balled up dirty on the floor and found little to no trace of all our adventures. Impressive.

On Spring ski missions  the Rhythm Tee was a go to base layer.
On Spring ski missions, the Rhythm Tee was a go to base layer.

Value


This is an expensive running shirt, but when compared to other merino wool base layers, it falls more appropriately in the mix. We wore this shirt a lot because we clearly liked what it had to offer. For a highly versatile layer that performs across elements and disciplines, we find value in an all-arounder, especially if it's as comfortable as this one.

Conclusion


The merino wool of the Black Diamond Rhythm Tee eliminates odor and offers superior breathability and unparalleled stretch. This Top Pick for Layering crafts a fit and comfort that is excellent for running or as a base layer. For the multi-sport enthusiast or the hundred-mile veteran, this shirt helps with thermoregulation, ventilation, and provides a comfortable fit with layers or a pack. The lofty merino wool is so light that it feels — and smells — like you aren't even wearing it.

Jeff Colt