How to: Cycling Apparel - Rain & Wind Protection

Semipermeable. This technical term tongue twister is the reason why modern waterproof jackets - also known as "hard shells" - have launched into a new realm of comfort. It describes a material property that actually sounds insane: water can’t get through on one side, but it can from the other. The magic lies in chemistry or better said at the molecular level. A membrane - a wafer-thin, film-like layer - acts as a bouncer: the big boys have to stay outside, but the little guys are allowed to leave. In practice: While rain and splash water in drop form hit a rain jacket and are blocked, sweat can escape as water vapour from the inside to the outside. The latter property is generally referred to as the "breathability" of a textile, more correctly it would be called water vapour permeability, since a garment cannot breathe actively itself. In diameter, a water vapour molecule is 3-5 Å (ångström) in size, a water drop is between 10,000 and 2 million Å. For comparison: 1 cm corresponds to approx. 100 million Å. Selectivity simply based on different size ratios - after all, an elephant can’t fit through a doggy door. 

Without the semi-permeable material properties we would stew in our own juice in no time. As physical activity increases, our body gives off heat - and at the same time reacts by producing sweat in order to regulate the temperature back down. But even at a resting state we perspire. Anyone who has ever stuck their hand into a closed plastic bag for a few minutes will feel how quickly it gets unpleasantly damp inside. Too much heat and humidity limit our physical performance - but so do cold and wet conditions.

A whole lot of nothing

For bikers windproofing is an equally important role, especially at the front. The "windchill factor" massively lowers the perceived temperature on the skin. An example: 5°C feels like 0.5°C at 25 km/h (wind) speed. If the skin is moist, e.g. through sweating, this effect is noticeably intensified. Pneumonia sends its regards. While every waterproof jacket doesn't let air through anyway, pure "windbreakers"- textiles that are completely windproof but not 100 percent waterproof - have clear advantages in terms of weight, packing size and water vapour permeability. Reducible to the size of a tennis ball, they fit in almost any jersey or saddle bag. High quality wind jackets - as well as corresponding softshell jackets - also have a membrane that is highly water-repellent (not proof!) and one hundred percent windproof, but at the same time allows maximum water vapour permeability. Incidentally, the term "windproof" refers to a permeability value which, purely sensory, no longer lets the skin feel a draught < 3 litres/m²/second).

DWR - Curse and blessing at the same time

Advertisements often show dripping water droplets as a synonym for waterproofness. However, this effect is not achieved by the waterproof membrane, but by a water-repellent impregnation - so-called DWR (durable water repellent). It is important for functionality, because if the uppermost layer of fabric is soaked with water, the passage of water vapour is extremely restricted. This creates the impression that the jacket is no longer waterproof - although "only" increased condensed sweat moisture is deposited on the inside. The DWR is also designed to keep dirt and oil out to protect the sensitive membrane.

The wow-factor in the saddle

On the bike the aha effect comes because the bent forward position closes the gap at the belly, the grip towards the handlebars makes the cuffs move exactly to the wrists, the shoulders come into position. And the pre-shaped sleeves allow the necessary grip position on the handlebars with more or less flared elbows. Depending on the area of use - Road , MTB or Tour - these three fit parameters vary a little, because of course the seating position on the Road is different from that on the MTB, Touring, Gravel or City bike. Nevertheless, these four "control points" are important indicators for the correct fit of a bike jacket. (Still) Independent of the cycling discipline. That's why:

More discipline, please!

If one delves deeper into the "discipline" requirements of Urban, Road or Mountain bikes, then in addition to the varying seating position, specific requirements such as suitability for everyday use, aerodynamics or robustness are also decisive. Because of course a Road cyclist attaches importance to a tight fit. The mountain biker wants to call his jacket a jacket even after a crash. And the bike commuter may even go for a beer after work. The most decisive role, however, is: how hard do you ride?. This is, just like the personal temperature sensation and sweat production, highly individual, a general recommendation for this or that jacket is therefore hardly possible. A rule of thumb:

1. Wetness and wind protection have top priority in order not to cool down in the wind. The more inhospitable the conditions, the better the protection against moisture in particular must be.
2. The longer you sit in the saddle in bad weather, the better the water vapour permeability and ventilation (for example through "vent zips", ventilation holes or mesh inserts) must be. Otherwise there is a risk of soaking through your own sweat.
3. The higher the average speed on the bike, the more important is functioning ventilation (through the membrane or via vents) when the jacket is closed. Uphill on a Mountain bike you can regulate the jacket climate relatively well via the front zipper. On the road bike this works poorly. The collar that inevitably beats in the wind slows you down and is annoying. Above all, however, it increases the risk of cooling in the chest.

All about the layers

In connection with functional clothing, the onion or layer principle is very often referred to. We also want to deal with this term - in several blog posts, which besides the outer layer in this text also deal with the topic of mid layer and base layer.