Head layer

Under your helmet, you can wear a cycling cap, mostly cotton (horrors!), for warmth. The brim shades eyes from wind and rain. Or in extreme cold, don a balaclava, which exposes only the eyes. Runners favor synthetic or wool caps.

Outer layer

Wind-stopping qualities are critical. If the wind gets through, it’s very difficult to stay warm. Visible colors also are important. Reflective tabs help drivers see cyclists and runners.

Middle layer

A jersey provides warmth. A runner’s mid-layer is more likely to be heavier and long-sleeved, with a half-zipper.

Bottom layer

Base fabric (in this case short sleeve) keeps moisture away from your skin. Cyclists prefer wool because it retains heat. Runners tend toward synthetic material and long sleeves.

Arm warmers

These can be easily removed if you heat up. There are sleeves for runners, but in the winter, most tend toward
long-sleeve layers.

Michael Esmonde of CycleLife wears cold-weather essentials for cyclists. (Marvin Joseph/WASHINGTON POST)

Warmth and a wind-stopping outer material are essential for cyclists. Runners can forgo the wind protection.

Leg coverings

Bibbed shorts stay in place and prevent chafing at the waist. Zippers at the bottom of leg warmers can be opened if weather warms up.

Socks and Booties

Wool socks retain heat but shed moisture. Booties cover vented shoes to block wind.