What's Cool In Road Cycling

Review: DeFeet Thermeator Socks & Assos Skinfoil Base

As winter hangs on across much of the 49th parallel, DeFeet’s Thermeator socks and Assos’ Skinfoil Ls baselayer make good sense for a lot of rides ahead. I’ve had both on test through the winter, so here’s my long term review…

DeFeet Thermeator Sock – US $14.99
DeFeet’s Thermeator socks were launched at Interbike 2013, but may only be arriving at your local dealers now as some dying issues held up production. They’re warm, durable, and comfortable, and my test has covered some cold & wet days this winter.

This is one review that’s coming after a serious few months of testing – I’ve worn a rotation of 4 pairs of test Thermeators every week over the winter, so I’m pretty confident in their long term performance. I’ve done several rides through the winter in the Thermeators, and this is a sock that walks the walk – they do live up to the promise of keeping my feet warm and dry.


Design & Construction
Made specifically for cold weather, the socks feature a thicker yarned foot and a tall 6” cuff, which makes them well suited for winter rides and outdoor use of any kind, and also as a daily wear item to just plain keep your feet warm.

They’re made of 66% THERMOLITE® polyester, 32% Nylon, 2% Lycra®. While the nylon and lycra add durability and fit performance (some stretch to hold them in place), the Thermolite makes these special. Thermolite is a hollow core performance fibre, that is said to be 30% lighter than comparable Merino wool yarns. As a polyester, the threads start life as a liquid, which is then extruded into a tubular shaped thread, which is used to make the yarn for these socks. That tubular shape holds air inside to aid insulation, but is less bulky and lighter than a non-hollow fibre – so it comes out lighter, and compresses more (when it’s inside your shoe).

Inside feels like a soft terry cloth.

The knitted pattern changes along the length of the sock from the cuff all the way to the toe. The upper is a knitted ribbed tube, that structurally helps the socks stay up and not slide down like those ol’ tube socks from gym class… The foot bed is a heavier pile that adds cushion as well as warmth to the heel, and toe box. The top part of the foot uses DeFeet’s original venting knit first created for their famous Air-e-ator sock, which helps air flow and also allows more room for cycling shoe tongue.

Turning the sock inside-out shows off the variations in construction – the cushy footbed, the vented foot top, and the upper.

They do keep my feet warm and dry. While I’ve worn them on several cold weather rides this season, where my feet always end up damp from the perspiration and water in these parts, I’ve also made a point of wearing them inside a very warm & moist environment of the Bogs Ultra-Mid Boots I tested in November. These boots feature a neoprene liner encased in rubber – so naturally there’s a reasonable amount of sweat retention inside. Over the course of several uses, I found that while my socks would get damp, they did not get cold – no doubt due in part to the Bogs boots, but this also carried on with other forms of footwear.

Mesh zone on the top of the foot makes for a thinner profile and also allows better ventilation.

While called a mid-weight sock, they’re on the bulkier side of “mid-weight”, but compress nicely into whatever shoes I’ve worn – from my summer cycling shoes to indoor-wear moccasins – they really don’t feel bulky inside shoes.

DeFeet says they dry faster than wool too, although my cold weather rides ended with these going straight into the wash (I didn’t hang around to see how fast they’d dry.) Polyester does not absorb water like natural fibres do, instead it disperses it, effectively forcing it away from your body. Spreading it out over a greater surface area helps it dry, thus keeping you dryer and therefore warmer.

After several washings, they’ve held both their shape and size – there’s been a tiny bit of size-reduction, but not like I’ve seen with wool or wool blended socks. It’s a spun polyester, which is fuzzy feeling outta the box, but they do tend to pill as a normal part of their long term wear, however overall construction has stood up well to at least 25 washings, and none of my four test pairs are showing any signs of structural deterioration.

If you value warm feet and a quality sock, these are worth a look.

DeFeet Thermeator Sock – US $14.99
• Buy em online at DeFeet.com or find ’em at your local dealer.

Assos Skinfoil LS Baselayer – $170
This Assos baselayer was the first piece of Assos gear I’ve worn. As a consumer, they were priced out of my reach, but thanks to Assos’ recent interest in the US market, a lot more of their gear is finding its way to cycling editors across the land. Assos’ reputation for highly technical designs set my expectations equally high, and lucky for me, as this is one nice item.


As the 6th warmest of their new seven-tier base layer system, the “LS.skinfoil_winter” set a new standard for base layer warmth at PEZ HQ. Through this past winter I’ve given this one a serious workout – both on the bike as intended across a variety of winter rides and as a daily-wear base on the coldest winter days.

Like the best fitting base layers should be, the fit is really snug and designed to work ideally with layering under other Assos items like jerseys and jackets, although my tester worked just fine under some other brands too. The polypropylene fiber blend of the fabric is very stretchy, and while the garment looks super small outta the box, it stretches out for a form-fitting and second ‘skin’ like feeling. Anyone used to wearing compression type clothing will be familiar with the feeling, (which is kinda weird at first) as there’s some pretty aggressive elasticity at work here.

The fabric features several sections of different textured weaves, intended to help airflow and

The snug fit helps the garment function by preventing bunching and maximizing airflow and moisture transfer around the body. The main body is a single tube knit design (created much like a sock) that eliminates any side seams, and allows for a more comfortable fit across a wider number of bodies than a seamed and paneled garment does. The only construction seams are at the shoulders as part of the raglan cut, and along the underside of each sleeve. The result is a really comfortable fit – it’s soft, and dare I say… snugly.

Warmth-wise, Assos rates this at 20 – 35F degrees, and while I never wore mine below zero, I did use it on several occasions in temps ranging from around 4C – 10C degrees, and even as a base under my street clothes during some cold evening outings over Christmas.


The neck is zippered to allow your head though the neck, and placed off center presumably to keep any cold air away from the front of your neck, it also provides a cool Euro look. On overall performance, I was impressed by how this handled keeping me warm. It indeed is best used for pretty cold days, but could also work well under a lighter shell if that’s how you like to roll.

At $170 it’s a purchase that might require some serious consideration, but then Assos has built a pretty solid reputation at the high end of the cycling apparel market as being worth the spend.

• See the Assos website

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