The world's most in-depth and scientific reviews of outdoor gear

Smartwool PhD Run Ultra Light Micro Review

An expensive ultra-lightweight running sock with poor durability.
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Price:  $17 List | $16.95 at REI
Compare prices at 3 resellers
Pros:  Lightweight, comfortable, both womens' and mens specific fit avaliable, highly breathable.
Cons:  Not durable, slips down on the run, foot slippage, expensive.
Manufacturer:   Smartwool
By Amber King ⋅ Senior Review Editor  ⋅  Jun 25, 2019
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64
OVERALL
SCORE


RANKED
#7 of 9
  • Comfort - 25% 6
  • Fit - 25% 7
  • Wicking & Breathability - 25% 8
  • Slip Prevention - 15% 4
  • Durability - 10% 5

Our Verdict

The Smartwool PhD Micro Elite is a lightweight running sock composed of merino wool and nylon material. It offers no additional comfort features and provides great breathability on the run. While we wanted to love this sock (as we love most things Smartwool), we couldn't help but be disappointed. The fit of this sock is on the smaller side and changed after washing (with the correct directions). It's not nearly as durable as a running sock should be, showing the potential to bust out after just 30 miles of testing. More importantly, on the run, the back of the sock rolls down, causing annoying stops along the way for some of our testers. In conclusion, these are not a favorite. If you're seeking a lightweight running sock, the Darn Tough Vertex No Show Ultra-Light is much more durable and a much better performer.

There is a more cushioned option that offers much better cushioning and durability. If you're not happy with our review, check it out instead.


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Overall Score Sort Icon
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Star Rating
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Pros Lightweight, comfortable, both womens' and mens specific fit avaliable, highly breathable.Great fit, wicks and breathes well, perfectly placed padding, unisex fitSuper plush and comfortable, ergonomic fit, men & women's versions, cute colorsSuper comfortable, fits great, durable, good padding.Deliciously comfortable, well-cushioned, affordable.
Cons Not durable, slips down on the run, foot slippage, expensive.Not as grippy within the shoe as some socks, low cut is a bit of a ‘tweenerMoisture management is sub-par, tight fit.Doesn’t wick moisture very wellBreathability is poor.
Bottom Line An expensive ultra-lightweight running sock with poor durability.The best overall running sock is comfortable, fits perfectly, and does a great job managing moisture.A super plush and comfortable running sock with a compressive fit.A super comfortable and durable lightweight running sock.Comfortable and affordable for long days pumping out the miles.
Rating Categories PhD Run Ultra Light Micro Thorlos Experia XCCU Feetures Merino 10 Coolmax Vertex Ultra-Light Balega Silver No Show
Comfort (25%)
10
0
6
10
0
9
10
0
9
10
0
7
10
0
9
Fit (25%)
10
0
7
10
0
9
10
0
9
10
0
8
10
0
8
Wicking & Breathability (25%)
10
0
8
10
0
8
10
0
6
10
0
8
10
0
5
Slip Prevention (15%)
10
0
4
10
0
7
10
0
8
10
0
7
10
0
9
Durability (10%)
10
0
5
10
0
8
10
0
7
10
0
9
10
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6
Specs PhD Run Ultra... Thorlos Experia XCCU Feetures Merino 10 Coolmax Vertex... Balega Silver No...
Material 48% merino wool, 48% nylon, 4% elastane 66% THOR WICK COOL, 20% Nylon ,1% Elastic, 13% Polyester Merino, synthetic 52% Coolmax Polyester, 44% Nylon, 4% Lycra Spandex 75% Drynamix Polyester, 23% Nylon, 2% Elastane
Warranty 100% Satisfaction Guarantee (witihin two years) 30 day guarantee Lifetime Guarantee Unconditional lifetime guarantee No Information Found
Ankle Cut Micro Low Cut No Show Tab No Show No Show Tab

Our Analysis and Test Results

A lightweight merino-wool synthetic sock that is totally barebones. While we wanted to love the Smartwool PhD Micro Elite it simply does not measure up to other running socks out there. It's nice and breathable but lacks functionality while running with questionable durability.

Performance Comparison


Running it out on a hot day in the San Juan mountains.
Running it out on a hot day in the San Juan mountains.

Comfort


The Smartwool PhD Micro Elite is a lightweight no-frills option that lacks any major cushioning. It's best for those that don't need plush materials or extra protection underfoot. Constructed of an even amount of Nylon to Merino Wool, it is comfortable to wear on the trail. When feeling the fabric with your fingers, it's a little scratchier than the Darn Tough and Swiftwick softs that are softer to the touch. However, on the roads and trails, it feels good to wear. We do enjoy the little bit of cushioning at the tips of the toes that adds a little protection.

Here we see next to no cushioning in the forefoot (similar to the heel). The material is soft against the skin  but the thin construction offers less comfort then thicker options. The good news is this sock does come with a more cushioned option.
Here we see next to no cushioning in the forefoot (similar to the heel). The material is soft against the skin, but the thin construction offers less comfort then thicker options. The good news is this sock does come with a more cushioned option.

Fit


In general, the fit feels a little bit small out of the package, but once you get the right size, it does okay. The collar has a thin elastic band, that we wish, was a little beefier. The tab on the back protects the Achilles heel, but is a little shallow and didn't cover up all the way against some shoes that have a higher collar. During a few runs, we had to keep stopping to pull this sock up as it slid down the shoe. This would easily be fixed by designing the sock with a longer Achilles section in the back and a more elastic band.

Here we stop to adjust the Smartwool PhD Elite on a hot  sweaty day. This sock is slippery and somewhat small  making it slip down the foot.
Here we stop to adjust the Smartwool PhD Elite on a hot, sweaty day. This sock is slippery and somewhat small, making it slip down the foot.

As we mentioned before, there is no additional cushioning in either the toes, forefoot, or heel. The elastic band around the arch of the foot keeps the sock in place, but doesn't offer a huge amount of compression, as we experienced with the Feetures Merino 10, a Top Pick for Comfort. Overall, the fit is okay, but some of our testers experienced it sliding down the foot when charging hard on flats.

The no-show tab is a little small and has a hard time protecting with shoes with a higher back.
The no-show tab is a little small and has a hard time protecting with shoes with a higher back.

During our testing, we focussed on the women's running sock, but a men's version of this sock it available as well. The women's sock features a more narrow profile, thinner heel, and a smaller fit. If you're a woman with a wider foot, you might want to opt for the men's version.

Wicking & Breathability


It's thinner construction offers great moisture management. The sock is thinnest under the arch and throughout the top of the foot, offering great ventilation. While the stitching is tight, the threads are able to effectively wick away moisture from the foot. This is a great option for running in the Summer, Fall, and Spring.

The fabric is tightly knit and offers good wicking and breathing capabilities.
The fabric is tightly knit and offers good wicking and breathing capabilities.

Slip Prevention


Like most thinner socks, the Smartwool PhD Micro Elite doesn't do much to prevent slippage. The merino wool-nylon fabric is slick and smooth and doesn't really stick well to the insole of a shoe. Since toe bump (on the downhill) can become an issue with these slippery contenders, we'd recommend a tighter fitting shoe if this is a concern. That said, there were no blister issues as a result of this slippage.

The tighter knit fabric means that this sock slips and slides in looser shoes or those with insoles that aren't super slippery.
The tighter knit fabric means that this sock slips and slides in looser shoes or those with insoles that aren't super slippery.

Durability


While the Ph.D. material used in Smartwool's sock is pretty durable in comparison to the rest of their fabrics, this still showed quite a bit of wear and tear after just the first use. The fabric pilled after the first wash (even with the correct washing directions). While this isn't a huge concern as it doesn't affect performance drastically, potential holes are.

A look at the forefoot that is almost worn through after just 30 miles on the trail.
A look at the forefoot that is almost worn through after just 30 miles on the trail.

After 30 miles, we note an area where the big toe touches the top of the fabric. Here, we noticed the beginnings of a small hole. Under the sock, in high use areas, we note compression of the already thin material and stitching seriously wearing down. This sock isn't nearly as durable as the Darn Tough Vertex No Show Ultra-Light which shows little to no wear and tear after this same use period. Also, after washing, it did shrink. Overall, we aren't super impressed with the durability and think there are more durable products out there to be considered with a similar make-up.

Here we see where our big toe pushes into the fabric  forming a hole. Unfortunately  this is the same place a hole was punched through with another pair of the same socks  owned by the primary tester. Unfortunately  this is not the most durable sock. Though  the more cushioned version offers better durability.
Here we see where our big toe pushes into the fabric, forming a hole. Unfortunately, this is the same place a hole was punched through with another pair of the same socks, owned by the primary tester. Unfortunately, this is not the most durable sock. Though, the more cushioned version offers better durability.

Best Applications


This thinner sock is best for those who appreciate a lack of cushioning and protection underfoot. While it's not our favorite because we experienced it riding down with looser trail shoes and its' shown some durability issues through our testing period, it still does well for the summer months. If you've already worn this sock and it works for you, it's perfect for all active sports in the summer, fall, and spring. Since it lacks insulation, it's not great for the winter months.

Running on hot days is a wonderful application for this super ultralightweight sock.
Running on hot days is a wonderful application for this super ultralightweight sock.

Value


While Smartwool has many great products, we aren't impressed by the performance and value of this particular product. It's pretty cheap for $17 and not worth the money. There are better, higher value options, with similar construction, such as the Darn Tough Vertex. For the same price, durability is much better, the lifetime guarantee is unparalleled and offers much better performance.

Conclusion


Smartwool has amazing products that are typically comfortable and great for all-around use. To be honest, we aren't especially impressed with the Smartwool PhD Micro Elite. While it is fairly comfortable for a lightweight sock, the fit is on the smaller side, it rides down on the run, and durability is questionable. If you're a hardcore Smartwool fan and have tried these socks, and they work, we are more then happy for you! However, we also believe there are better running sock options out there for the price.


Amber King