Something that hasn't been mentioned yet: bare aluminum handlebars will draw heat from your hands very quickly, rubber grips (or other insulating material) will act as a thermal break and reduce that significantly.
Likewise, a cotton bartape wrapped handlebar might not be the best thing for winter riding if your hands are getting cold.
A tip from
http://chiccyclist.blogspot.com/
"Winter cyclists, don't forget to take your hands off the handlebars and stretch and move them, rub them together, whatever, to keep the blood flowing.
Happy hands keep cyclists happy."
Good luck.