How to: Cycling Apparel - Base Layer, the Layer on the Skin

Base layer, first layer, functional shirt, undershirt, underwear - call it what you want. But do it right! Because hardly any layer of clothing is underestimated as much as the first layer directly on the skin. It contributes significantly to your personal comfort and thus to your performance on the bike. Similar to the mid-layer, the base layer has to master a balancing act that no cotton shirt in the world can do. The simultaneous requirements:

•       Warming = skin-near preservation of the air layer warmed by the body 
•       Cooling = removal of excessive heat and steam, aka sweat

Abase layer is required to spread sweat moisture that cannot be passed directly to the outside as fast as possible from the skin to the fabric. Why is that? This shortens the re-drying time and prevents a wet layer from cooling down quickly, especially in windy conditions. But there is - as always - not one do it all product, that is: the one base layer that fits perfectly for all bike activities. The choice of the right base depends on the adequate combination of fibre selection, shirt construction and personal body climate management. 

Which fibre can do what?

How well a base layer meets the requirements - retaining heat and removing moisture - depends on the material and the processing of the individual fibres. Merino wool fibres are thirsty: they can absorb between 20 and 35 percent of their own weight in moisture, synthetic fibres only about 5 to 15 percent. This is why functional shirts made of merino wool feel dry for a long time when sweating. Once the absorption capacity is reached, however, every shirt feels wet to the skin - regardless of the type of fabric. But that is exactly what is supposed to be prevented. Let us look at the strengths and weaknesses of the materials processed in base layers:

1.    Synthetic materials: They are usually made of polyester or polyester-polyamide blends. Although synthetic fibres absorb less water than wool, they are specialised in wicking moisture away from the body as quickly as possible via their surface (wicking effect). Due to the fast distribution, more moisture can be released to the outside, as a result functional shirts made of synthetic materials dry faster. They are somewhat lighter, more robust and more complex to process - and the raw material is cheaper. Their disadvantage: there are bacteria that love on our sweat, or better said the body fats and salts in it. Unfortunately, they can settle down quite well in synthetic materials. Their excretions - one can already guess at the word - cause bad smells. Bad for team sports or the social (or just not) sitting together during a ride break...

2.    Wool fibres: Merino wool is used exclusively for direct skin contact, as it is significantly softer and finer than normal new wool. For comparison: On average, new wool has a thickness of 30-50 microns (1 micron = 0.001 millimetres), merino wool between 15-24 microns, a human hair between 50-100 microns. As described above, wool can absorb up to a third of its own volume of moisture without feeling wet. However, if the tanks are full, it takes correspondingly longer for the base layer to dry again. In addition, wool fibres are not as robust and abrasion-resistant as their synthetic counterparts. However, more and more base layer manufacturers are working with hybrid fibres in which merino wool fibres are wound around a core of nylon or polyester. This combines the strengths of both and deals with their weaknesses quite well. An enormous advantage of merino fibres is their ability to prevent the typical sports smell of sweat. Where this ability comes from has not yet been fully clarified, but it is assumed that the bacteria simply cannot attach themselves as well to the surface of the wool fibres. The result can be seen or smelled in any case - well in this case not.

What's the point of body mapping? 

Smart and frequently used is so-called "body mapping". In doing so, base layers are constructed in such a way that different substances are used exactly where they can optimally support the athlete's body in its function. For example, by using different thicknesses on the torso and shoulders, different air permeability on the stomach and back or merino wool inserts on the neuralgic sweat zones. Base layer sections with Windstopper membranes are also included: Provided you avoid rain like the devil avoids holy water, they even make wind jackets or vests superfluous thanks to a windproof but water vapour permeable membrane that is close to the body. However, when it comes to Windstopper underwear, you have to be aware that their membrane always acts as a kind of brake on water vapour and sweat moisture does not pass through as well as through a knitted or woven item. Nevertheless: Those who prefer to do without a real jacket in cold, dry weather, but instead wear a warm jersey (plus mid-layer) and the wind protection for it directly on the skin, will probably be very happy with a Windstopper undershirt.

Base layers - a purely winter topic? 

The topic of base layers is by no means limited to the cold season. Even in summer, base layers make perfect sense when choosing the right material and the right construction: the body surface, drastically increased by a mesh undershirt, accelerates the evaporation process and thus creates a supportive regulating factor in the temperature balance even at high temperatures. So when your mum used to say 'Put on an undershirt, it's cold', she was absolutely right. But only in part: she forgot about the summer.