Choose a base layer that will serve to wick perspiration away and keep you dry. It should be tight fitting against your skin. Cotton t-shirts won’t cut it—they stay wet and pull heat away from your body. But Polypropylene, silk, polyester, Thermax, Thinsulate or wool won’t. Any of those materials are good base layer options.
This layer—which can be made of polyester, fleece, wool and other synthetic blends—is meant to keep you warm and also works to keep moisture away from your skin. But it shouldn’t fit as snugly as your base layer does. A wool jersey/sweater, or a fleece will do the job nicely.
Your outermost layer of clothing should be windproof and waterproof. Shells made out of Gore-Tex or other similar materials work great. You might want to choose a shell that offers armpit zippers and other ventilation features to help keep your temperature regulated.
Below the Belt
Choose a pair of cycling-specific spandex that will cut the wind and keep you dry. Look for a pair of long bike tights that are made for winter riding. They’ll likely have a fleece lining to keep you comfortable and warm. If it’s not bitter cold outside, cycling shorts and leg warmers should do the trick.
Toasty Up Top
Wear a “skull cap,” balaclava or headband under your helmet depending on the outside temperature. This thin layer is designed to insulate your head and wick away moisture—without overheating.
On your hands, choose a pair of windproof gloves. Shifting will keep you from wearing full-fledged mittens, though they keep your hands the warmest. However, there are cycling-specific gloves available that keep certain fingers together and others separate for warmth and shifting ease.
Don’t overlook your feet when putting together a winter riding outfit, as they will likely get cold first. Choose thicker winter socks—typically made of wool—or double up on two thinner pairs. Wear a pair of booties or shoe covers overtop of your mountain bike shoes to keep your feet warm and dry. Investing in a pair of winter cycling shoes may be advantageous—especially if your feet still feel frosty inside booties.