It depends on how cold it gets where you live. Below 52 or so, i would wear bike shorts under thermal tights, instead of leg warmers. I wear anything from a regular long sleeved jersey with a wind jacket, to wool tops that are wicking with a jacket, or thermal tops. Also, you need full finger gloves. I wear Wooly-Bully socks (both light and medium weight) and I have neoprene booties for my shoes for when it gets in the 40's. I can't stand having cold feet. I have a cap that goes under my helmet to cover my head, too.

All this gets me to the end of November in New England. Then it's just too cold for me.