You should wear heavy socks although not to heavy

In case your hands get cold, you should carry a pair
of lightweight glove liners will you as well. If you
have to stop to take care of a problem, the liners will
protect your hands from the cold.

Glasses
Glasses that wraparound and provide maximum protection
from the wind are best to wear in the winter. You can
protect yourself from debris, as well as the cold.

Socks
You should wear heavy socks although not to heavy. A
sock that is overly heavy will make your shoes tight,
cut off circulation, even make your feet cold. You
should try lightweight socks, as they will keep your
feet warm without bulk. If you need an extra layer,
try silk ski socks as they are very warm and also
extra lightweight.

Underwear
Polypropylene is the best material here, as it is
lightweight and best for colder temperatures.

Wind protection
Moving air is the biggest cause for losing body
heat. By having good wind protection you'll be able
to vent perspiration while also protecting yourself
from windchill. You should choose pants and a jacket
based on durability, breathing, and price as these
types of clothing can get very experience.

Helmet and liners
Your head is very important, as you lose 50% of your
body heat through your head. A helmet is designed to
keep you cool in the summer, not warm in the winter. A
fleece liner inside your helmet will keep your head
and ears warm during winter riding.