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Smartwool Merino Sport Ultra Light Review

Packable weather protection that skillfully incorporates Merino into a well-ventilated shell
Smartwool Merino Sport Ultra Light
Photo: Smartwool
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Price:  $130 List | $96.73 at REI
Compare prices at 3 resellers
Pros:  Well-ventilated, body-mapped Merino panels
Cons:  Lack of drawcords, billowy
Manufacturer:   Smartwool
By Aaron Rice ⋅ Review Editor  ⋅  Jan 8, 2020
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75
OVERALL
SCORE


RANKED
#4 of 13
  • Wind Resistance - 30% 7
  • Breathability and Venting - 30% 9
  • Weight and Packability - 20% 7
  • Fit and Functionality - 10% 6
  • Water Resistance - 10% 7

Our Verdict

The Smartwool Merino Sport UL windbreaker is really best summed up by the statement that lines the inside of its storage pocket. "This shell delivers the comfort of Merino with super light, packable weather protection for a life lived in unpredictable conditions." Toss this compressible, ultra-lightweight shell into your pack or running vest, and know that you're well-covered should a storm blow in unexpectedly. The Merino wool is not incorporated into the fabric, but rather is used to improve large, body-mapped underarm vents, putting to work the natural power of wool to efficiently wick up and evaporate sweat. While this jacket is lacking a bit in terms of features — particularly drawcords to lock-down in a strong wind — it delivers when it comes to packable protection from the elements.

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Pros Well-ventilated, body-mapped Merino panelsLow price, simple and effective design, tiny packed-size, impressive DWR coatingLots of zippered pockets, ease of packing, elastic brimAffordable, mesh-backed ventilation, large zippered hand pocketsAffordable, large hand pockets and hood
Cons Lack of drawcords, billowyNo feature to stow-away hood, thin material can feel clammy during high-output activityGoofy looking brimmed hood, swampy, lack of DWR treatmentRelatively heavy, lack of water resistance, oversized stuff sackBillows in anything more than a breeze, lack of features
Bottom Line Packable weather protection that skillfully incorporates Merino into a well-ventilated shellThe best overall value and performance in a lightweight package that sets the category standardBest-in-class storage in a lightweight, ripstop-nylon shell, all at an affordable priceA price-point option that balances wind resistance and breathability, but lacks in terms of weather proofingHolding it down for the classic windbreaker, in style and function
Rating Categories Merino Sport Ultra... Patagonia Houdini Rab Vital Windshell Flyweight Hoodie Columbia Flashback
Wind Resistance (30%)
7.0
8.0
8.0
7.0
5.0
Breathability And Venting (30%)
9.0
8.0
7.0
9.0
6.0
Weight And Packability (20%)
7.0
8.0
7.0
4.0
5.0
Fit And Functionality (10%)
6.0
7.0
9.0
7.0
5.0
Water Resistance (10%)
7.0
8.0
6.0
3.0
5.0
Specs Merino Sport Ultra... Patagonia Houdini Rab Vital Windshell Flyweight Hoodie Columbia Flashback
Measured Weight (size M) 4.8 oz 3.9 oz (size L) 4.7 oz 7.6 oz 5.7 oz
Material 100% nylon outer, 54% Merino wool / 46% polyester liner, DWR coating 100% nylon ripstop, DWR finish Hyperlite nylon WindWall: 100% Recycled Polyester woven with DWR finish Water-repellent polyester
Pockets 1 zip (chest) 1 zip (chest) 3 zip (2 external hand, 1 internal) 2 hand 2 hand
Safety Reflective Material? Yes reflective logos on chest, back, right arm; stripes on cuffs and seat hem No (company states reflective logo on left chest, too small to really be visible) Yes, reflective logo on chest and back No No
Stowable Pocket? Yes: chest pocket Yes: chest pocket Yes: internal pocket Yes: hand pocket No
Cuff Style Half Elastic Half Elastic Half Elastic Elastic Elastic
Hood Fits Over Helmet? No Yes Yes Yes Yes

Our Analysis and Test Results

Skillfully employing 150 weight Merino mesh into large underarm vents, the Merino Sport UL is a perfect jacket for runners to take from the starting line to a night on the town. Despite its ultralight nylon construction, this jacket provides solid wind and water resistance — we found ourselves impressed on both a blustery ridgeline and light rain after a long adventure run.

Performance Comparison


This jacket was one of our favorites for trail running, thanks to...
This jacket was one of our favorites for trail running, thanks to awesome ventilation and comfortable mobility.
Photo: Jill Rice

Wind Resistance


For a shell designed as a breathable outer layer, the Merino Sport UL is impressively wind resistant. The thin nylon build is ultra-lightweight, so don't expect it to be warm on its own, especially in a strong, wintry wind. But our lab testing supported what we found in the field, that this jacket does a nice job of keeping gusts from penetrating to the core — just as long as you don't have your arms in the air.

Better facing the wind than catching it to the side... the large...
Better facing the wind than catching it to the side... the large underarm vents were definitely an entry point for a cold wind to chill us to the core.
Photo: Jill Rice

A small, elastic cinch point — combined with Merino mesh panels on the inside — work together to keep the hood in place and your ears warm when the wind really picks up. We do wish that designers included a drawcord at the hem, as air can easily stream from the bottom up and out of the underarm vents and can cause the jacket to billow. But the inclusion of a storm flap behind the zipper will help keep you protected from head-on winds.

Breathability and Venting


A top performer in terms of breathability, the highlight of the Merino Sport UL are the two huge underarm vents. These body-mapped panels are made out of Merino Sport mesh, and true to Merino-form, do a fantastic job of wicking away moisture from the sweatiest part of our body. These mesh panels work in conjunction with smaller vents across the top of the shoulders to keep a consistent airflow across an area that tends to trap heat.

Body-mapped, Merino wool vents... how better to improve efficiency...
Body-mapped, Merino wool vents... how better to improve efficiency of breathability?
Photo: Jill Rice

After a particularly tough run, we did observe that there was a sweat-soaked pattern across the upper back. But without noticing any heat pooling in these areas during our run, it certainly didn't affect the comfortability of movement over miles of trail.

Smaller, slot-style vents on the shoulder help improve airflow...
Smaller, slot-style vents on the shoulder help improve airflow throughout the jacket.
Photo: Jill Rice

Weight and Packability


This jacket claims "ultralight" status in its name, and while not all marketing claims are true, in this case, we have to agree. The Merino Sport UL tips the scales at sub-five ounces, and even more importantly, feels equally light and airy to wear.

Smaller than a standard Nalgene bottle, this packed-parcel was...
Smaller than a standard Nalgene bottle, this packed-parcel was easily further compressed to nearly half this size.
Photo: Jill Rice

A fully squared-off pocket makes it much easier to stuff into itself than others. The storage pocket includes a harness loop and a small corner drain hole — to afford a bit of airflow to help fight off any mustiness, just in case you end up packing this jacket away before it fully dries out.

Simple weather protection in an ultralight package.
Simple weather protection in an ultralight package.
Photo: Jill Rice

Fit and Functionality


The Merino Sport UL, while indeed sporty, has one of the nicer cuts out of our current crop of wind jackets. The athletic fit airs on the tighter side but offers a looser hem that lies flat and doesn't bunch up when on the move. If you're looking to fit in with the 26.2 crowd, then this jacket has the simple runner's style that works well out on the town, whether you're clocking miles or hanging out with friends.

Light enough to float, warm and breathable enough to keep things...
Light enough to float, warm and breathable enough to keep things moving even in snowy weather.
Photo: Jill Rice

The inclusion of body-mapped panels is a thoughtful addition, not only in terms of breathability but also with regard to mobility. The Merino mesh panels offer just the right amount of stretch, and the Merino lining of the hood is soft next to your face, both worn down and when you have to go hood-up. While the elastic at the back of the hood does a good job of keeping it in place — particularly when wearing a hat — we do dock this jacket some points for not having a drawcord at the hem to help cinch down when the wind really picks up.

Smartwool keeps the weight of this jacket down by cutting out...
Smartwool keeps the weight of this jacket down by cutting out drawcords, instead opting for a single elastic band at the back of the hood to hold it in place.
Photo: Jill Rice

Water Resistance


The DWR finish on the Merino Sport UL was one of the most effective in this review. In our shower test, the water-repellent coating was awesome at beading up water and allowing it to run off the jacket front smoothly. We were a bit worried about the size of the underarm vents as an access point for weather, but the natural hydrophobia of Merino wool seems to help keep any light rain at bay.

Good for a long-while, but under the weight of continuous snowfall...
Good for a long-while, but under the weight of continuous snowfall we found that this nylon shell soaks through in patches, particularly in the arms and shoulders.
Photo: Jill Rice

The Merino Sport UL is prepared for quick-passing storms. But we found that under more consistent precipitation — like a light snowfall over the course of a ski tour — that the thin nylon of the jacket is more prone to soaking through over a period of hours.

A quality DWR finish does quick work of beading up rain water, as...
A quality DWR finish does quick work of beading up rain water, as verified in our lab testing.
Photo: Jill Rice

Value


As with any product involving the revered material that is Merino wool, the Merino Sport UL carries a slightly higher price tag than many of the other jackets included in this review. However, we believe that this wind jacket does offer a solid value based on its performance — particularly if you are a runner or engaged in a high-intensity activity where breathability is paramount.

A perfect addition to the runner's closet, keeping you comfortable...
A perfect addition to the runner's closet, keeping you comfortable when on the move all year-round.
Photo: Jill Rice

Conclusion


A major contender for the adventure running crowd, the Smartwool Merino Sport UL windbreaker is a force to be considered for super-lightweight, packable weather protection. What it lacks in features to improve wind resistance, it makes up for with superb fit and performance during high-exertion activities.

Aaron Rice