It's still a little cool for riding (Not to mention the snow and ice)

And inexpensive way to ride in the winter is by wearing baselayer clothing. In older parlance, thermals, long johns...

But with winter sports being more "mainstream" than they were years ago and more money involved in them, more suppliers and designers became interested. Todays base-layer clothing is light, flexible, and warm.

Dickssportinggoods.com_MensWinterClothes_Baselayers

Don't dismay Ladies, they have a ladies selection as well as one for the youth.