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How to: Cycling Apparel - Rain & Wind Protection

Moritz & Andi 23. September 2019

Filthy weather - and still out on the bike. But what do I actually have to pay attention to with waterproof and windproof bicycle clothing?

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.

La Palma Road bike pass road fog summer

The variance of external conditions: Warm, humid and a lot of wind.

Forest Winter Frost Fall MTB

Alternating intensity of movement in frost and dryness.

Road bike autumn winter frost climb wavy terrain

Cold temperatures, dry roads, varying speed.

Gravel Bike Snow Winter

Low temperatures, snow-covered trails, varying speed and intensity.

Mountain bike Mud Water Forest

Mud and water.

Road bike wet cold autumn winter

Wet and cold.

Proof and permeable

In 1969, the US American Bob Gore succeeded for the first time in developing a semipermeable membrane. Gore... Ring a bell? Gore-Tex is now used by many people as a synonym for waterproof textiles. Even though the “GTX” jackets & co. are extremely popular, nowadays there is a huge range of membranes from various manufacturers. 

The  is indicated by the water column. Its value tells us how high - in mm - the water pressure in the form of a column must be per square meter of fabric until it allows moisture to pass through. Most high-end hard shells are at values of 20,000 mm and above, but 10,000 mm is already sufficient in most cases. The big challenge, however, is to achieve a very good water vapour permeability aka breathability despite waterproofness. There are two big players on the market: microporous membranes made of polytetrafluoroethylene (PTFE) and non-porous membranes made of polyurethane (PU) or polyester. In Gore-Tex, whose core is a PTFE membrane, the water vapour molecules - i.e. sweat - move through over 1.4 billion/cm2 of microscopically small pores. However, these small channels can be blocked by the body's own fats and salts or even dirt. That is why - contrary to the still persistent myth - it is imperative to wash your Gore-Tex jacket when necessary.

Poreless membranes made of PU or polyester are based on a chemical-physical molecule transport. Caution getting nerdy: Hydrophilic, i.e. water-loving, components bind the water molecules and conduct them through hydrophobic, water-repellent, structures to the outside. This process accelerates the higher the temperature and humidity gradient, i.e. warmer and more humid inside than outside. If this is the case, a so-called "partial pressure" arises. So when physical activity increases, bikers literally crank up the exhaust hood. Logically, this system only really works properly up to an outside temperature of about 20 °C. For comparison: if you open the bathroom window after a hot shower on a cool day, the water vapour is drawn out much faster than on a hot summer day. However, the wafer-thin membranes alone are too fragile to be used exclusively to make clothing. For this reason, they are bonded to substrates at high temperature and "packaged". The result is a multi-layer sandwich construction called a “laminate". Commonly used are 3-, 2.5- and 2-layer laminates. As a base, they have a preferably robust, abrasion-resistant outer fabric made of nylon (polyamide) or polyester, including the membrane and on the inside either a firmly laminated lining (3-layers), an applied protective coating (2.5-layers) or a loosely suspended fabric (2-layers). 3-layer variants are considered the highest quality solution because they are more robust and durable.

Multi-layer jacket Endura rain protection breathability

The decisive factor for the wearing comfort of a jacket under stress is the water vapour transmission. If the removal of sweat moisture does not work sufficiently, even the best moisture protection is useless.

dirtlej suit overall mountain bike bad weather rain wet protection

Very popular among Mountain bikers, because very sensible, are overalls. Preferably with short legs in shorts style. They reliably keep the elements out, but are primarily suitable for descent-oriented cycling.

Gore-Tex Shakedry laminate

Gore-Tex Shakedry special case: In favour of weight, packing size and water vapour permeability, no outer fabric is used in the laminate in Shakedry technology.

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.

Windstopper windproof jacket Windchill

If you are "only" out in the cold and not in the rain, a windproof jacket is the better choice for you: the windproof membrane counteracts windchill, sweat moisture can escape better than with (most) waterproof jackets.

Beading effect Softshell wind jacket DWR

The DWR coating ensures a dry outer fabric. This is essential for multilayer, waterproof jackets. But also with many softshell jackets (and some windbreakers) now standard.

Fit doesn’t come from fitness

A paradox: most cyclists don’t try on their hard shell or windbreaker in the position that they ride in. Instead, they slip inside, stand upright in front of the mirror and examine what they see. Hopefully this looks good (even better if you stand with your legs apart and hold your breath, for the athletic looking chest), but on the bike it often leads to the realization "Damn, this doesn't really fit!”. Experts also call this phenomenon "Shop Fit". 
Exaggeratedly depicted, it is exactly the other way round with a really well-fitting bike jacket. Standing up, you think to yourself: Why does it pinch your shoulder? Why are the sleeves so long and why is my belly sticking out? This is the “Bike Fit”.

Cycling specific fit Bike-Fit

A cycling specific fit is - not only on the Road bike - of crucial importance. If the jacket seems to fit perfectly when standing upright: Watch out! Much more important is the position on the bike.

Dirtlej Suits full body suit rain cover

With the Dirtlej suits, waterproof full body suits, a serious problem is eliminated: There is no gap between jacket and trousers.

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.
Waterproof socks mud pack

And another tip: waterproof socks. Keep your feet warm and dry. Any time of the year.

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.

What experiences have you had in nasty weather? Which type of jacket works best for you? Give us your feedback!"

Moritz

Moritz

Blog comments are published with first name and first letter of surname.
Blog comments are published with first name and first letter of surname.