Assos has a reputation for eye-watering prices and the GTO Winter LS DermaSensor Base Layer doesn’t disappoint in that regard. While it is very good it’s matched by competitor options for less money. Unless you can find it at a discount, it’s tough to recommend.
Pros
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Almost completely seamless
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Tall collar
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Extra breathability over your mouth and nose
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Warmer than expected
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Lots of stretch
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Perfect fit
Cons
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Expensive
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It doesn't matter what time of the year you are dressing for; a base layer is a must-have. It's the foundation that your whole system of clothing builds on and because of that, we have a wide range of options in our list of the best cycling base layers. There are options for the summer that form a barrier between your jersey and transport water away from your skin. For shoulder season rides, we have options that extend summer clothing with added features like wind block materials. Then, for winter, there are choices for the times when you need all the features and every last bit of warmth.
If that last group is what you are looking for, Assos is surely on your list of brands worth consideration. We included the standard winter LS base layer in our list and it's long been a favourite of mine as well. This year though, Assos brought out another option. The Assos GTO LS DermaSensor Winter Base Layer builds on what you get with the standard long-sleeve base layer but takes it to a whole new level. It also takes it to a whole new level of price but that doesn't mean it's not worth consideration. The obvious question is how closely the price tracks with the performance. Is it really that much better than the rest? With that in mind, I put it to the test. If you are looking for the absolute best winter base layer, keep reading to see if Assos makes it.
The GTO tag doesn't mean warmer but rather technological details no matter the cost (Image credit: Josh Ross)
Design and aesthetics
The Assos GTO LS DermaSensor Winter Base Layer is the pinnacle base layer that Assos offers. It falls under the GT, endurance-focused, line of products but it carries a GTO tag. That's a tag that only comes attached to the very best, and the most expensive, products that Assos makes but it's not actually a marker of quality.
What GTO stands for is more about design features and technology than quality or price. It's also worth noting that when talking about winter gear, GTO does not mean the warmest that Assos offers. Warmest is not always the best solution and more than anything, what GTO stands for is the best solution. If it works it gets included and there are no guard rails that limit the effects on price.
Given that description, a base layer is still a base layer. You can only get so complicated and feature-rich and subtraction is often the name of the game. In fact, that is exactly the trick that makes the GTO DermaSensor Winter Base Layer what it is.
There are almost no seams in the GTO DermaSensor Winter Base Layer. There are a couple on the end of each sleeve, as well as a couple in the armpits, that gather the fabric to add a bit of strength. There are also a couple that run over the cap of each shoulder to create a tighter turn radius. That's it though. There aren't multiple panels to stitch the base layer together, instead, it's done as a single three-dimensional knit.
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In most places that you'd expect to see a seam, you'll find a spot of extra stretch instead(Image credit: Josh Ross)
At the end of each sleeve, the seam gathers the material(Image credit: Josh Ross)
The only traditional seams are at the shoulders(Image credit: Josh Ross)
Using a seam at the shoulder makes a tighter radius(Image credit: Josh Ross)
Assos calls out the fabric as a jacquard knit but that description doesn't really describe the uniqueness. Jacquard describes a pattern that's part of the material rather than added as a finishing technique. Despite not describing the one-piece construction, it does describe an interesting part of the aesthetics. In the areas where you'd expect to find seams, you'll instead find a change in the pattern of the knit. These areas are more open with higher stretch and they do create an aesthetic detail but, in most places, that's more of a happy accident. The only place that differs is on the front where the brand uses it as a purely aesthetic detail to create its iconic stripe.
Another place that Assos employs the open-knit structure is on the extended neck. The GTO base layer mirrors that of deep winter options from a variety of companies and extends the neck. In this case, it not only covers the full length of your neck but it’s also long enough to extend all the way up over your nose and mouth when you need it to. In that configuration, you’ll notice the jacquard knit and open structure again. This time it’s used to make breathing easier and reduce the moisture that is likely to be absorbed.
What is actually responsible for making this whole structure work is the fabric. Jacquard knit may not describe it but you can find the clues to the design changes by looking at the composition. The Assos winter long-sleeve base layer uses primarily polypropylene and there is 6% elastane mixed in. Meanwhile, the GTO version switches to a mix of polyester and nylon and ups the elastane to 12%. Elastane is another name for Spandex so even if nothing else changed, that ups the stretch considerably. Nylon and polyester are also both higher stretch than polypro as well as being silkier and better at absorbing water. What you’ve got is a 3D knit paired with a soft and silky high-stretch fabric. It’s certainly unique, but does it work?
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There's no performance reason to have these two strips of extra stretch down the chest but they do look great(Image credit: Josh Ross)
and they connect to the this spot on the top of the neck that makes breathing easier(Image credit: Josh Ross)
Performance
What's a good winter garment review without my customary story of braving some outlandish weather for an extended period of time? The truth is I've actually been spending time riding in the Assos GTO LS DermaSensor Winter Base Layer since early winter of last year. However, the most recent adventure definitely fit the bill as an outlandish adventure and it was the coldest temperatures I've been in with this base layer.
It was cold enough that I actually expected it to be beyond the capabilities of the GTO base layer. The final Strava recording shows a range of -4C/24F at the low end up to 8C/46F in the middle of the day and that's stretched out across a full five-and-a-half-hour day. It's cold enough that if you'd asked me ahead of time what I thought was ideal, I would have said either the Assos Ultraz winter base layer or maybe even the Equipe RS winter mid-layer without a base. I would have been wrong though.
Both of those are better options for a day that was consistently closer to the cold side of the range than the warm. This wasn't that day though and it showed what the GTO base layer is best at handling. Like the Johdah jacket, the extra price of the GTO base layer doesn't buy you warmth, it buys you adaptability.
Adding extra breathability at the spot where the neck sits over your mouth and nose is a clever feature made possible by a 3d knitting technique (Image credit: Josh Ross)
A swing that wide is more difficult to handle than consistently cold temperatures. The warmest part of the day was when I was carrying my bike through the snow hiking under the sun. Over my base layer, I had the 7Mesh Seton jersey and the PAS normal Essential Shield jacket and even during the peak of the day, I left everything zipped up. I was just as comfortable when the temperature dropped in the shadow of the mountain early morning and late afternoon.
The other thing you pay for with the Assos GTO is comfort. Assos base layers tend to be my favourite for this reason but the GTO base layer ups it even more. I'm not bothered by the few seams that exist in the other base layers but having almost none is a joy. The fabric is silky, and the high stretch is incredibly comfortable. This base layer is warm, adaptable to a wide range of temperatures, and very comfortable.
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The same technique that allows for a seamless construction also makes the inner surface incredibly soft(Image credit: Josh Ross)
Another side effect is no need for extra bulk at the edges of the garment(Image credit: Josh Ross)
Verdict
I am never afraid to tell you that an expensive piece of gear is worth your money for a wide range of reasons. Pushing technology to the limit can be expensive and it helps us all if a brand is willing to develop something expensive and make it available for sale. Some people will buy it at a higher price and over time the price will come down. This time, I can't in good faith make that recommendation.
The Assos GTO LS DermaSensor Winter Base Layer is very good. The marketing rhetoric you can read on the Assos product page is completely true. It's warmer than you'd expect, it feels fantastic against your skin, the seamless design is a joy, and the addition of breathability over the mouth is clever. I still don't think most people should buy it at the price Assos is selling it.
Assos has a fantastic product, it's just not worth double the price of everything else on the market. The standard Assos winter base layer is incredible and it costs less than half the price of this one. If you feel like you want more features, look at PAS normal. The PAS Normal Studios Thermal Long Sleeve Windproof Base Layer adds a wind stop front panel, Polartec Power Wool fabric, and a hood with a concession for helmet straps.
Or, perhaps you want the best. If you can afford to pay a premium for the most luxurious base layer on the market, you won't regret the purchase. Just understand that the return on your investment is small.
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Testing scorecard and notes
Design and aesthetics
If it’s possible to have a stylish base layer, this is the one. It’s also incredibly well designed.
10/10
Thermal management
One of the things that the extra price of a winter GTO product buys is better usability across a wide range of temperatures. A couple of points have to come off because there are warmer options for so much less money
8/10
Next to skin feel
As good as it gets.
10/10
Comfort and fit
Assos often refers to the “regularFit” of the Mille series of products but the difference between the racing fit is incredibly subtle. If you are looking for a relaxed fit, this isn’t it but it’s still incredibly comfortable. I love it but I have to take some points for the way it’s presented.
8/10
Value
The GTO costs double the price and the performance is maybe five percent better. Despite how good it is, this isn’t a value proposition
1/10
Overall
Row 5 - Cell 1
74%
Tech Specs: Assos GTO LS DermaSensor Winter Base Layer
Josh hails from the Pacific Northwest of the United States but would prefer riding through the desert than the rain. He will happily talk for hours about the minutiae of cycling tech but also has an understanding that most people just want things to work. He is a road cyclist at heart and doesn't care much if those roads are paved, dirt, or digital. Although he rarely races, if you ask him to ride from sunrise to sunset the answer will be yes.
Height: 5'9"
Weight: 140 lb.
Rides: Salsa Warbird, Cannondale CAAD9, Enve Melee, Look 795 Blade RS, Priority Continuum Onyx
