This article pertains to preparing for riding in cold temperatures and even rainy conditions. Personally I never start out a ride if it's raining. Some call me a wussy, so be it! If rain is a possibility I will carry a rain jacket and a hat with a brim in the front. I'll refer to items I've found useful when confronting chilly temps and overcast conditions.
First is the "One Mile Rule." This rule states that if you are warm the first mile of any ride you are over dressed. Your body temperature will increase quickly as you start a ride so try not to wear so much that you are warm just starting out.
(Does anyone else have anything they can't live without for winter riding? Please share it in the comments. Thanks!)
GLASSES: My glasses have a variety of lenses so I change from dark to either a lighter color or clear lenses when the sun is hidden from view. Sometimes when I stop the lenses fog up so I just move them away from my face (down to the end of my nose) until I start riding again. I have found that anti-fogging sprays do not work.
UPPER BODY: Always wear a wickable fabric next to your skin, then layer with similar fabrics if possible. Cotton is about the worst thing you can use next to your skin, it does not wick. Cotton keeps sweat next to you and you will never get warm.
As the temps drop I add more layers starting with a long sleeve jersey, vest, and wind breaker. These can be shed and placed in your jersey pockets when/if it warms up. I use thermal vests or jackets when I'm sure I will not be removing any outerwear. Most thermal jackets have rear pockets so you will have access to whatever you keep in your jersey pockets.
When first starting out I usually place a few sheets of newspaper between my jersey and the next layer, it really helps to keep you warm. After you warm up you can toss the newspaper into an appropriate container.
LOWER BODY: Another saying is "below 60 degrees cover your knees." Since I don't own leg warmers (never liked them) I use knickers. As it gets colder I add tights and when it's really cold I'll put on thermal tights all over my knickers. I don't like being cold!
HANDS: In the fall when it's cold in the morning but will warm up by 11, I use disposable gloves while others use thin full finger gloves under their regular cycling glove. When it's obvious I will need to keep my fingers covered all day I will use full finger gloves.
FEET: I hate cold feet! When my feet are cold and wet is when I head for home, the car, or Bart. For cool temps I use sandwich baggies between my socks and shoes then use toe warmers for added protection. For colder days I use full booties that are not made of neoprene (they make your feet sweat). Sometimes two pair of socks will help keep my tootsies warm.
RAIN: Since I don't particularly like riding in the rain I avoid it when possible. As mentioned above I do carry a clear plastic rain jacket that can fold up small enough for a jersey pocket. The rain jacket helps ward off the rain to some degree but it's mostly to keep you warm due to the denseness of the material. Gortex and similar materials help wick away some of the sweat but most of them are too bulky to fold into your jersey pocket. Since I must wear glasses to see properly I use a brimmed hat under my helmet to keep my glasses clear of the rain. It works for the most part.
One last thing is regrouping on a hilly ride. My idea is if it's cold, regroup at the bottom of a descent. When it's cold regrouping at the top of a hill makes us cold not only from sweat but winds as well. In the warmer weather I try to encourage regroups at the top of a hill.
Stay warm and dry and have fun.