Winter Cycling - Winter base layer?

What is a good base layer that will wick the sweat away when dressed in layers during winter? I am currently using Underarmor Cold Gear as a base layer but it seems to hold more mosture than I expected. Gets a bit chilly on the downhills even with a windbreaker on. Have not tried it below freezing yet but I suspect it will be a problem.
What is a good wicking base layer for winter? If it is thin, can I wear the Underarmor over it as a light insulation layer?

Underarmour would be considered a base layer. Also, the goal is not to sweat... period. At least not much. I know all the "wicking BS" but the best solution is to not sweat very much. This is achieved by not dressing too warmly.

Underarmor heat gear is a so so base layer. Underarmor cold gear is utter crap as a base layer. Its great for the apres ski group to wear while sitting around the chalet fireplace trying to impress the opposite sex. It is not a good base layer (for the reasons youve already found), and all underarmor is marketed as a fashion item, so is priced accordingly, 2x as much as it should be. Yes it would make a better mid layer than a base layer.

Some materials to look for are polypropolene (has tendency to hold smells), polartech powerdry, capalene, driClime are all excellent ones to use. Merrino wool base layers are also popular, but although they feel good and keep you warm when wet, they usually are wetter since they dont wick as well.

Unless your in extremely cold areas always try to get silkweight, in as tight as fitting size as possible. Loose base layers dont touch your skin so cant wick away moisture. Anything thicker than silkweight is trying to add thermal properties which are better handled by your mid (thermal) layer.

Polartech Powerdry with X-static are my favorite. Capalene a close second.
Heres an example of a few decent ones:

http://marmot.com/products/product.php?cat=base&subcat=27&style_id=I0152

http://www.mec.ca/Products/product_detail.jsp?PRODUCT%3C%3Eprd_id=845524442619593&FOLDER%3C%3Efolder_id=2534374302699185&bmUID=1159579626811

http://www.mec.ca/Products/product_detail.jsp?PRODUCT%3C%3Eprd_id=845524442617588&FOLDER%3C%3Efolder_id=2534374302699185&bmUID=1159579664956

http://www.mec.ca/Products/product_detail.jsp?PRODUCT%3C%3Eprd_id=845524442618984&FOLDER%3C%3Efolder_id=2534374302699185&bmUID=1159579664950

Sporthill makes some good stuff. So does Craft and Sugoi. The XC ski stuff works quite well. You can get the underwear with windblock in front which vents out the back.

Merino wool!

Helly Hanson, or any good cycling jersey made of polypropelene.

The best stuff is polyester or polypropelene ski underwear. I have used under Armor. It's not very functional for really cold weather. It works great for football players who wear coats on the sidelines and have thick pads over large portions of the body while involved in intense play.

The knit fabrics next to the skin work very well as they both wick and trap warm air and breath.

+1 Craft Baselayers work well for cycling in sold weather.. They also have a base layer with extra frontal protection, called windblock base layer..

duofold stuff is great and they make a single and a double layer for a base then +1 on the merino wool its light and warm. Then a windproof or waterproof breatheable shell and you're gold

I've found that the old, blue polypropelene stuff I have from college backpacking is still the best moisture mover as a base layer. This was a cheap $10 set from who knows where. It has shrunk a lot, so it probably shouldn't go in the dryer. My plan is to get a few cheap sets and rotate to avoid the odor they retain. I've also found that the wicking performance of a base layer is affected by the layer on top of it's ability to wick or absorb. Odd as it may sound, cotton does a great job of complimenting polypro. I still wouldn't use cotton in cold, but the principal is sound IMO.

I agree with Portis that avoiding sweat is priority 1, then the wicking ability of your base layer is less critical. I find the best way to avoid sweat is to reserve rain gear for conditions where precipitation is less desirable than prespiration. A soft shell layer makes this possible in most conditions.

polypro base layer, merino wool mid layer(s), lightweight shell that blocks the wind but has plenty of ventilation.