Men's Pro Team Thermal Base layer with Collar | Winter Cold Weather Cycling  | Rapha

What is the Base Layer? How to Choose the Right One?

This winter, whether you’re relaxing outdoors or going on a multi-mile hike, here’s what you need to know about base layers to stay warm.

If you want to put together the ultimate layering system, then start by focusing on the foundation of that system—your underwear (aka “base layer”). Starting with the layer that touches your skin, comfort in the outdoors is possible.

Why do you need a base layer, and what does it do? Regarding this crucial item of clothing in your wardrobe, we provide all the information you need.

What is Base Layer Clothing?

A base layer should serve as a constant “second skin” throughout the day because it is the layer that is closest to your skin. Base layers give you an additional layer of insulation while absorbing and evaporating sweat to keep you dry and comfortable.

Base layers are adaptable clothing items that come in a variety of fabrics and designs with advantages best suited to particular climates and conditions.

This base layer guide will examine the characteristics of various base layer types, explain what makes them unique, and assist you in selecting the best base layer for your needs.

How Should Base Layers Fit?

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When trying on a base layer, make sure it feels snug against your skin while still allowing you some range of motion. Don’t give in to the temptation to purchase base layers that are smaller than your typical dress size (especially if you’re shopping online). Base layers should fit snugly against your skin.

Remember that our clothing is made with the intention that it will fit snugly if you are unsure of what size base layer to buy.

Do I Need Base Layers?

Base layers are crucial in the winter because they add an additional layer of insulation and help to keep you dry by wicking sweat away from your skin.

Base layers are a must if your body temperature will fluctuate greatly throughout the day, or if you plan to engage in any activity that could result in sweating in a colder climate.

What is Better—synthetic, Silk, Wool, Or Bamboo?

Your search criteria will determine what you find. The majority of base layers are made of synthetic, silk, or wool materials. New base layers are also being produced from bamboo, which is a fantastic vegan substitute or a choice for people whose skin reacts negatively to wool fibers.

Here’s a quick primer on each:


Polyester is one of the synthetic materials that are used most frequently for long underwear. Additionally, you may encounter fabrics made of blends, nylon, polypropylene, or rayon. Spandex-infused fabrics have a comfortable stretch and can be tight without feeling confining. Synthetics have the following characteristics:

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  • Super dry: The driest feeling is provided by synthetic fabrics because they are the best at wicking and removing sweat.
  • Durable: Although there is no such thing as an indestructible base layer, synthetics are your best bet if you’re looking for the most robust option.
  • Odor retention: Inhibiting the growth of bacteria that cause odors is something some synthetic materials add as a finish. It helps to have some tolerance for stench if you plan to go more than a few days between washes.


Silk is known for its legendary softness, which belies the fact that it makes a good base layer for simple activities like a leisurely fall hike or an outdoor concert in the evening. Silk has the following characteristics:

  • Moderate wicking: You should be fine as long as you don’t exceed your target heart rate range; some silk undergarments have a finishing touch to enhance wicking.
  • Suppleness: Silk is always a lightweight option that can be easily tucked under other layers; however, it lacks durability.
  • Odor retention: Since silk does not naturally resist odor, it must be washed after each use.

Merino Wool

These aren’t the scratchy wools of your grandparents. The soft, ultrafine fibers of merino wool have nearly entirely replaced those of traditional wool. Additionally, wool can be blended with other materials, such as spandex, to improve fit and flexibility. Merino wool has the following characteristics:

  • Wicks well: Wool retains some moisture in its core, so it won’t make you feel cold, but it won’t feel as dry as synthetic fabric. When it gets wet, it will also take longer to dry.
  • Cools, too: When temperatures rise, the moisture in the fibers’ cores releases, providing some cooling when the temperature is high.
  • Moderately durable: It will last longer when worn underneath other layers, but if you wear it alone under bulky pack straps, the constant rubbing may cause the fabric to wear through. For greater durability, you can also choose a base layer made of a wool and synthetic blend.
  • Odor-free: The fact that wool is extremely resistant to odor-causing bacteria (and naturally resistant to them) is unquestionable, even if you don’t believe wool aficionados who claim endless days of sweaty wear without a discouraging whiff.
Review: Rapha Winter Base Layer |


Bamboo base layers are a relatively recent invention, but they’re a fantastic substitute for anyone looking for a vegan option or if wool fibers might irritate your skin. Bamboo materials are a good option for sports as well because they are anti-microbial and frequently wick moisture even better than wool or silk.

The only drawback of bamboo layers is that they are still more expensive than synthetics and are not as widely available. If you’re vegan, allergic to wool, or seeking a natural fiber option for active sports, pick a base layer made of bamboo.


Because it draws heat away from your skin and takes an eternity to dry after you perspire in it, cotton is a terrible material for a base layer. Make any other choice.

Can You Wear a Base Layer on Its Own?

Yes, absolutely, even though your base layer might essentially replace an undershirt, it will frequently be the only layer you’re wearing. If it’s warm outside, you might go outside in just your base layer and a backpack that contains a fleece and waterproof jacket.

Even in cold weather, you can start sweating and getting warm very quickly when you start climbing, so it’s likely that you’ll be taking off those outer layers until you stop for lunch.

Conclusion: Wear a Base Layer in Winter

Base layers can be incorporated into your outfit for a variety of activities. The most obvious one is skiing because you’ll need an extra layer to stay warm and combat the chilly mountain air.

They are also a great way to add warmth without adding bulk to your walking attire on chilly days or to wear underneath shorts while running or cycling. Because of their ability to generate or absorb heat, base layers and thermal clothing can be worn year-round, so you can wear them on a hike no matter the weather.


What is the Purpose of a Base Layer?

The layer that is closest to your skin, known as a base layer, should serve as a constant “second skin” throughout the day. Base layers provide a layer of warmth while absorbing and evaporating your sweat to keep you feeling warm and comfortable.

Are Base Layers the Same as Thermals?

While both base layers and thermals do the work of protecting your body from cold and keeping it dry, one is more specialized in the latter than the other. In contrast to thermal clothing, which has the primary function of keeping you warm, base layers are designed to keep you dry.

When Should You Wear a Base Layer?

Contrary to popular belief, layering is actually a good idea in hot weather provided the base layer is wicking and breathable. Therefore, a well-constructed cycling base layer can be worn on cold days, hot days, in summer or winter, when racing, training, or trail riding.

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