A Bit of History!
Back in the good old days, a cycling rain jacket was nothing more than a black trash bag with a hole cut in the top for your neck, and one in each side for your arms. The trash bag worked pretty well for keeping the cyclist dry from the rain. However, cyclists generate so much heat and sweat from their own bodies, that without good ventillation, they become soaked from the inside out. To make cycling in the rain more comfortable, apparel companies started developing rain specific clothing that focused not only on being waterproof, but breathable as well. Waterproof, breathability is accomplished through a combination of technical fabrics and garment construction.
What to Look for in a Cycling Specific Rain Jacket
Today, cycling specific rain jackets range in price from
"Waterproof" vs- "Water Resistant"
To be truly "waterproof", the garment must be made from a "waterproof" fabric and have sealed, or taped seams so that rain does not leak in through the small perforations made by sewing needles during the construction of the garment. Sealing and taping seams takes special equipment and extra time. As such, it adds substantially to the cost of the garment. If the garment is made from a "water resistant" fabric, that usually means that a coating has been applied to the fabric to help repel water. Water resistant fabrics work very well for light rains, or drizzels, but may get soaked over time and are not considered to be "rain gear". If you are looking for protection from rain, you must look for garments made from "waterproof" fabrics, not "water resistant" fabrics.
Breathability and Moisture Management
|Being "waterproof" means that moisture does not pass through the fabric... rain does not come in, and sweat does not go out. Cycling causes us to generate so much heat and sweat, that the only way for a cyclist to stay dry inside and out is to have a garment that is not only waterproof, but breathes and wicks moisture. Breathability and moisture management are obtained through fabric construction, and/or venting.
Vents are designed to allow air to come into the garment, keeping the cyclist from overheating. A vent can be as simple as a mesh panel, or as detailed as specially designed zipped or Velcro® vents which allow the cyclist to adjust body temperature by opening and closing vents as needed. The cost of a garment will be greatly affected by the number and type of vents that the garment has. Simple mesh panels that can not be opened and closed, let air in, but also are not designed to keep water out. More sophisticated (and expensive) vents allow air in, but are also designed to keep water out.
Waterproof fabrics fall into three catagories: "PVC, or poly vinyls", "Coated Fabrics", and "Laminated Fabrics".
PVC or POLY VINYLS
These fabrics are completely waterproof, but they have no ability to wick moisture or breath without the addition of exterior vents or mesh panels. PVC's are generally used in the less expensive, $20.00 clear rain shells.
COATED & LAMINATED FABRICS
All coated or laminated waterproof fabrics have an outer layer, or face fabric. The main function of the face fabric is to provide a durable outer shell. To make the face fabric waterproof, the inside of the fabric is coated, or laminated with a protective moisture barrier.
Breathability of a particular fabric is also a function of temperature differential (Delta T). When the environment on the inside of the jacket is warmer than the environment on the outside a driving force is created. The higher the Delta T, the higher the driving force, and therefore the more breathable the fabric.
The breathability of a particular fabric depends upon the inner barriers resistance to evaporative transfer (RET). Hydrophillic coatings and Hydrophillic membranes rely on the chemical and molecular properties of water molecules to push perspiration away from the body to the external face of the fabric. The lower the RET rating of a particular fabric, the higher the breathability. As a result different waterproof fabrics can have different levels of breathability even when the Delta T and weather conditions are identical.
The outer surface of most waterproof-breathable fabrics are treated with a durable water-repellent coating (DWR). This chemical treatment forces water to bead up and roll off the surface of the fabric. DWR coatings do not work when pores become clogged with dirt, or salt from your body's sweat. Regular cleaning is important to maintain the performance of DWR treatment. All DWR treatments wear off over time and eventually need re-proofing. When a garment begins to “wet-out”, water hitting the fabric surface starts to give the impression of soaking into the face, rather than beading up and running off. It is time to restore the DWR coating. You can easily restore the DWR water beading qualities of applying a proofing agent to the fabric. For more information
Other Special Features
Cycling specific rain jackets are designed with an "elongated tail". This means that the back of the jacket is cut longer than the front of the jacket so that the cyclists lower back is covered when they are bent over on the bike. Fleeced Lined Collar: A lot of manufacturers line the collar of their jackets with a fleece fabric. The fleece is not only soft, making the jacket more comfortable, but is usually made from a fleece that is designed to wick moisture. The fleece also helps prevent air from blowing down the neck of the jacket when the cyclist is bent over the bike.
Reflective Tape and Piping:
Visibility is very important, especially when you are cycling in the rain. Most technical rain gear is usually produced in a bright yellow, or other highly visible color. However, that is changing, and many companies are now offering some nice color alternatives. In order to increase visibility, most manufacturers place relective tape or piping on the jacket. Reflective material is very visible (a great safety feature), but is extremely expensive and will add substantially to the cost of a jacket.
Price point jackets usually have a simple elastic cuff. More expensive, and technical jackets have adjustable cuffs which allow the cyclist to adjust the wrist of the jacket so that it fits snugly, but comfortably with or without gloves so that air does not blow up sleeves while cycling.
Adjustable hem's and Waists: Shock Chords allow a cyclist to adjust the girth of the jacket (usually at the hem or waist, sometimes at the collar) so that wind does not blow freely through the jacket causing it to blow up like a balloon.
"Pit Zip" is the term used for underarm vents. They are great for adjusting body temperature while riding. Good pit zips should be easy to open and close with one hand so the cyclist can open and close them while on the bike. More expensive jackets have a mesh panel or other method of preventing the opening from flapping in the wind.
"Wind Flaps", "Storm Flaps", "Covered Zippers", are all terms used to mean that the front zipper is covered with fabric. They can be inside the jacket, or out. They prevent air and water from blowing through the teeth of the jackets front zipper.
Most high end rain jackets have hoods that fit over a cycling helmet. These store in the collar or are detachable.
If you need to pack & carry your rain jacket with you on a ride for a surprise rain, or long trip or tour, then it will be very important to find a jacket that can fold up small and be stored in a pocket or pack that can be carried with you on the bike. How small a jacket can be folded will depend on the fabric in the garment as well as the amount and type of reflective tape & piping and zippers and vents in the jacket.
Most cycling rain jackets will have rear pockets for storing items that you may need to have access to during a ride. In the alternative, they will have openings in the rear of the jacket that will allow you to access the pockets in your jersey if necessary.
Some manufacturers give the jacket sleeve "articulated elbows". That means that they design the sleeve of the jacket to have a bend at the elbow to folow the contour of the cyclist arm in the drop position.
Rear Light Clips:
For added visibility, some manufacturers have clips attached to the rear of the jacket that can hold a light.