as follows. I live in NY and have mountain biked in cold and snow down to 20 degrees. I even made studded tires so I can enjoy the season longer. But that was after I put together this collection of clothing for the cold.
1) Performance Triflex tights with Chamois. They are windproof on the front yet breath through the backs of the calves and thighs. $80 and worth EVERY PENNY,
2) A Pearl Izumi balaclava is KEY. They are very thin, but do an amazing job of keeping whole face and head warm. You can pull away from lips for very heavy breathing or pull around neck if you get too hot. Added bonus, fits under helmet with NO PROBLEMS
3) Pearl Izumi Neoprene booties. Not only do they block wind on ventilated bike shoes, but they are WATERPROOF! I have biked across a (supposedly) frozen puddle about a foot deep, only to fall through and have to put my foot down into the freezing water. It was just a dab, but my feet were dry. Try that with just plain bike shoes
4) Smart wool socks. There is no substitute. Trust me. Get them and you will were nothing else (on your feet that is;) )
5) Gloves are tricky. There is a lot more personal preference here. Best advice is to try and grip something like a handlebar when trying before buying. Too much padding in palm bunches up and makes things tough. I have a pair of thin windproof that work great. A snot wiper or something soft on the backs of the thumbs is more important than you can imagine.
Get out there and enjoy. The peace and quiet of empty trails is more than worth the time and effort it takes to get dressed up for a trip. Other tips I have collected on my own or have heard work great but have not tried
A) You will dehydrate without being as aware as you are in the summer. Drink fluids as you normally would. A hydration pack under your jacket will keep the liquid from freezing provided you BLOW THE LIQUID BACK INTO THE PACK when done drinking! I have had warm tea FREEZE in the tube, and make it impossible for me to drink for the rest of the ride. Drink, blow, repeat.
B)The Lobster AmFib gloves mentioned above have gotten rave reviews elsewhere.
C) I have heard of Vaseline on feet, and then plastic bags, then socks. Some people swear by this. I swear buy Smartwool. A lot less messy
D)Make sure your gear is TOP SHAPE before you leave a warm home. Replacing broken cables and chains on the trail in the snow SUX! REALLY BAD! Chains and cables subjected to snow and road salt disintegrate at the farthest point out on the trail. Change them now and avoid problems.
E) Carry that cell phone, and make certain it works at different points on your trail BEFORE you have to use it in an emergency. Keep it close to body. Frozen cell phones don't work, and 20 minutes of trying to warm it up before you use it is frustrating and uncomfortable.