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Smartwool Merino 150 Lace Thong Review

Our testers found it difficult to recommend this pair because of its ill-fitting and uncomfortable design
Smartwool Merino 150 Lace Thong
Photo: Smartwool
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Price:  $30 List | $30.00 at REI
Compare prices at 3 resellers
Pros:  Lightweight, breathable
Cons:  Runs large, poor fit, stretches out, uncomfortable lace pattern, expensive
Manufacturer:   Smartwool
By Trish Matheny ⋅ Review Editor  ⋅  Jul 13, 2021
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64
OVERALL
SCORE


RANKED
#11 of 13
  • Comfort - 35% 5
  • Fit - 30% 5
  • Drying Time - 25% 9
  • Packability - 10% 9

Our Verdict

Directly out of the packaging, the Smartwool Merino 150 Lace Thong has a great aesthetic; however, we believe comfort is more important when selecting a pair of travel underwear, and we found this fabric to be itchy as well as the sizing to run quite large. We also found ourselves needing to adjust this undergarment frequently throughout the day. It's a serviceable option, but we strongly prefer the Icebreaker Siren Thong as a merino wool thong within the same price range.

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Price $30.00 at REI
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Pros Lightweight, breathableSilky fabric, stays in place, cute design, breathability, bonded seams prevent chafing and panty lines, quick dryingMost comfortable fabric, well-constructed design, quick drying, true to sizeLightweight, quick-drying, merino woolInexpensive, soft, quick-drying, no bulky seams
Cons Runs large, poor fit, stretches out, uncomfortable lace pattern, expensiveExpensive, runs largeExpensive, heaviest thong testedLess practical fit, expensiveImperfect fit for some
Bottom Line Our testers found it difficult to recommend this pair because of its ill-fitting and uncomfortable designSuper comfortable, breathable, and a flattering fit that allows you to forget about your undies and focus on your adventureThis exceptional thong-cut garment is a super comfortable, well-designed product that excels in urban and backcountry travelThis is a high quality, flattering, and super comfortable bikini-cut model made out of quick drying and soft merino woolSoft, stretchy, and quick to dry, this value-forward garment won us over without making us pay a high price
Rating Categories Smartwool Merino 15... ExOfficio Modern Bi... Icebreaker Siren Thong Icebreaker Siren Bi... Under Armour Pure S...
Comfort (35%)
5.0
9.0
9.0
9.0
7.0
Fit (30%)
5.0
9.0
9.0
8.0
5.0
Drying Time (25%)
9.0
9.0
8.0
8.0
9.0
Packability (10%)
9.0
8.0
7.0
8.0
8.0
Specs Smartwool Merino 15... ExOfficio Modern Bi... Icebreaker Siren Thong Icebreaker Siren Bi... Under Armour Pure S...
Material 87% Merino Wool, 13% Nylon 82% Nylon, 18% Spandex 83% Merino Wool, 12% Nylon, 5% Lycra Spandex 83% Merino Wool, 12% Nylon, 5% Lycra 68% Nylon, 32% Elastane
Measured Weight (oz) .4 oz (M) .8 oz (S) .9 oz (M) 1.1 oz (S) 0.7 oz (S)
Flat-lock Seams Yes Seamless Yes No Seamless
Cut Tested Thong Bikini Thong Bikini Hipster
Cuts Available Bikini, thong Bikini Thong, bikini, hipster Bikini, thong Hipster, cheeky, thong

Our Analysis and Test Results

The Merino 150 Lace Thong features a new innovative lace design to enhance breathability and decrease overall weight. Weighing in at just 0.35 ounces, this thong meets the criteria for ultralight and minimalist missions into the backcountry. It was also very fast to dry during our side by side testing. However, we found the size to run large and were less than impressed by the feel of the material when compared to the competition.

Performance Comparison


After lots of testing, we found that we preferred a smoother...
After lots of testing, we found that we preferred a smoother material to the textured lace of the Smartwool Merino 150 Lace Thong.
Photo: Trish Matheny

Comfort


To determine the level of comfort that each garment has to offer, we considered the type of material as well as the thickness, whether or not the garment felt soft or itchy on body, we accessed the breathability in each pair and finally we noted the performance during activities such as trail running, climbing, and yoga. The Merino 150 Lace Thong was not our first choice to get the job done.

Our testers concluded that the aesthetics of the lace detail is not worth sacrificing the next to skin comfort found in a softer, more uniform material. While we loved the breathability of the lace, we found ourselves partial to a smoother merino fabric.

While the lace detail of the Merino 150 Lace Thong was aesthetic and...
While the lace detail of the Merino 150 Lace Thong was aesthetic and increased breathability, it also contributed to an uncomfortable next to skin feel.
Photo: Trish Matheny

Fit


To determine the best fit we carefully assessed every waistband, determined the amount of stretch found in each garment, we noted which brands felt true to size or ran large, and we paid close attention to the overall coverage and leg openings. We found the frontal coverage lacking, and the overall fit was larger than expected when compared to other competitive brands.

While the fabric is quite stretchy, our concern is that over time this thong will lose it's already ill-fitting shape, and continue to stretch until it has no use at all. We were also disappointed by the waistband or lack thereof. There is no waistband, simply a flat lock seam that does not help control the garment and keep it in place during activity, a key component of our fit metric. Ultimately, the poor fit, the lack of control in the waistband, and the amount of stretch in this thong prevented us from giving it high marks.

The ultra thin waistband of the Merino 150 Lace Thong lacked the...
The ultra thin waistband of the Merino 150 Lace Thong lacked the desired control (it moved around significantly) and felt distracting.
Photo: Trish Matheny

Drying Time


To properly assess the amount of time it took for each garment to dry, we dunked them in streams and washed them in the backcountry before wringing them out by hand and hanging them to dry on a line in the sun, so we could record our observations.

We also did a more thorough test on a spring day in Victor, Idaho at 6200 feet with 58 degree temps, partial sun, minimal wind, and these are our results. The breathability of the lace fabric allowed for the Smartwool Merino 150 Lace Thong to dry the fastest with a time of 40 minutes out of the pairs of thongs that we tested. We know how important it is to have a quick-drying garment on an extended trip or in the backcountry so based on this metric alone, the Merino 150 Lace Thong is a competitive choice.

A compact thong cut is easy to hand wash and dry on the go.
A compact thong cut is easy to hand wash and dry on the go.
Photo: Trish Matheny

Packability


For this metric we consider the amount of space each garment would require within your suitcase or backpack as well as the weight. So we got to work by weighing each garment individually on our scale and began to compare each garment side by side. We understand that this can be a very important consideration, especially when carrying all your necessities on your back for an extended period. It can also be a great reason to consider a thong cut over a heavier hipster model.

The Merino 150 Lace Thong weighed in at .35 oz—that's one of the lightest weights we've ever recorded for travel underwear. During our side by side comparison, we found the differences between each thong cut to be minimal and would feel comfortable recommending any pair for your next minimalist adventure based on bulk alone. In cases where weight is the determining factor, the Merino 150 Lace Thong is an obvious choice.

We carefully weighed each pair of undies to determine the lightest...
We carefully weighed each pair of undies to determine the lightest overall.
Photo: Trish Matheny

Value


The Merino 150 Lace Thong is one of the more expensive pairs of underwear that we tested from thongs to hipsters. While we were impressed with its fast drying time and minimal weight, we do not believe it is worth the investment based on overall comfort, fit, and performance.

Conclusion


After taking these undies for multiple trail runs, various yoga classes, and up vertical rock walls, we concluded that the poor fit and discomfort from the lace pattern were our deal breakers. In our opinion, it doesn't matter how light a garment is or how quickly it dries when you are constantly adjusting yourself throughout your favorite activity.

While not our favorite of the thong cuts, the Merino 150 Lace Thong...
While not our favorite of the thong cuts, the Merino 150 Lace Thong features one of the lightest, quickest-drying fabrics that we tested.
Photo: Trish Matheny

Trish Matheny