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Ultraz Winter Long-Sleeve Skin-Layer - Men's

4 out of 5 stars
5 Reviews


Size Chart


Ultraz Winter Long-Sleeve Skin-Layer

Wicking sweat in summer helps keep you cooler, however, in winter it’s all about keeping your skin warm and dry. Assos’ Ultraz Winter Long-Sleeve Skin-Layer works in tandem with your outer layers to wick sweat away from your body to avoid becoming saturated and cold when cycling in winter months. The seamless construction ensures next-to-skin comfort by eliminating seam lines and weight. Assos uses medium-weight yarn to supply the insulation you need, but not so much that you’ll feel stuffy when hitting climbs or harder training sessions. And carbon fiber threads are integrated to add durability to this soft baselayer.


  • Moisture wicking, mid-weight, thermal layer for cold cycling in winter
  • Transfers moisture away from skin to keep you warm and comfortable
  • Seamless construction for enhanced comfort next to skin
  • Carbon fiber threads added for strength and durability
  • Close fit to reduce bunching under your heavier cycling jacket
  • Item #AASZ021
synthetic, 3% carbon fiber
Insulation Weight
Recommended Use
commuting, cross-country, enduro, road cycling, trail
Manufacturer Warranty

Overall Rating

4 based on 5 ratings

Review Summary

1 Stars - 0 reviews
2 Stars - 1 reviews
3 Stars - 0 reviews
4 Stars - 2 reviews
5 Stars - 2 reviews

Fits True To Size

Screen reader users: the following list provides a visual scale to illustrate the product fit. Please refer to the heading above for the fit type in text.
Runs smallTrue to sizeRuns large

What do you think about this product?


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4 out of 5 stars

February 21, 2024

Very expensive but very warm

I've put it through the wringer

Like most things Assos, this baselayer is eye-wateringly expensive. That being said, it's a solid base layer. My winters are too mild to require the heavier duty Assos jackets and too cold to get away with only the spring/fall lineup. I find that combining this and --to a lesser extent-- the winter base layer extend the range of my spring/fall gear to exactly what I need. Four stars only because the fabric of the Assos base layers can be a bit scratchy if you're not used to them. The spring/fall base layer is the worst offender. The thicker base layers (such as this one) aren't nearly as bad. They all, however, bind up Assos' fleecy sleeve lining and require some adjusting. Not a deal breaker but a bit annoying.


Originally reviewed on Backcountry.com

5 out of 5 stars

January 16, 2024

Very versatile, very comfortable

I've used it several times
Size Bought:
5' 10"

I bought this to wear under a light jacket for cold days in Texas -- 30's. Use Castelli Alpha Ros Fly jacket jersey (torso insulated zippered liner) and can ride in the 30's still or wind. I noticed some saying itchy but I do not find that to be the case and other bases I do find itchy. Indeed, I love the feel. It is also very versatile in temp range. When 30's warms to 50's unexpectedly, I can unzip and it does not get hot. I find I do not notice hot or cold in the range from 30's to low 50's -- just riding and not thinking about my temperature. I may be a size too big for my build, but it feels great, hugs well. 5' 10", 173, 40" chest, 32 waist.

5 out of 5 stars

December 30, 2023

Great base layer!

I've used it several times
Size Bought:
5' 7"

I have worn the Ultraz several times. I highly recommend it! It is a little thicker vs the other Assos base layers and does a great job of keeping your warm and wicking away perspiration. I have worn it on cloudy days in temps from 47 F to 56 F and it worked very well. Even though the Ultraz is a little more expensive vs the other Assos base layers....it is worth the extra money. Please note that I also use the other Assos base layers and highly recommend them too. No. I Don't work for Assos. :0 I just like their base layers. Also. Note that the Ultraz is very stretchy so make sure you look at the Assos size chart before ordering. Sizing. I have a 38 chest and a 29 inch waist. I have a size Medium and I have an athletic build. I could have probably used a size Small too.

klip862235 k
2 out of 5 stars

November 7, 2021

Not that Warm and Slightly Itchy

I've put it through the wringer
Size Bought:
5' 10"

The fabric is super strechy and unlike anything else I've worn. That's neither good or bad. Overall, the shirt is not very warm in comparison with all the other shirts I've worn. It's also slightly itchy. It's not too bad, and when you ride you won't notice it. Not recommended. You can buy better performing underlayers for far less money.

4 out of 5 stars

December 18, 2020

It will help keep you warm

I've used it once or twice and have initial impressions
Size Bought:
5' 9"

Since I ride year-round, staying warm is understandably important to me. The base layer is of excellent quality. While it is form fitting, it is also very stretchy so follow the size chart. My size is a II. I'm 5'9", 182 lbs with a 35" waist and 42" chest if that helps. It is a little bit pricey however the garment is made in Italy and NOT China so you have a higher quality garment that won't fall apart as long as you follow Assos guidelines for care and washing. Recommended.

Michael S