Cool weather/cold weather cycling clothing

Since cycling is active generally one makes enough heat to stay warm. The key is keeping cold wind off your skin. Then add more insulation/layers as needed (ex for me: hands and feet).

TL;DR: For a little cool (50F/10C to 70F/20C) it is wind chill that gets me cold, so I cover skin. The standard set up is (say it with me: "two way zipper") cycling vest and a fleece neck bandanna and a thin tuque under the helmet. Cooler? Add arm warmers and tights. Hands? Add liner gloves. Feet: booties.


Colder temperatures?
The gear below takes me to 0C/32F no problem and I ride down to -10C/+20F and cross country ski to a bit colder, and with adjustments this gear system works perfectly well.
At all times colder weather means taking shorter rides or taking frequent rest stops somewhere indoors to warm up. I do not treat cold weather cycling as an outdoors all day long activity like in summer time. Also below 15F/-10C the cold gets serious and frostbite and hypothermia become real risks. So pay attention to wind chill charts and remember that cycling itself is adding a lot of extra wind chill.


Head:
-Under the helmet: thin wool/merino tuque
-if colder I add a fleece headband/ear warmer thing
-You may prefer a shaped tuque to get better full-head & ears protection, 
-cotton balls (like for makeup etc) stuffed in ears can keep wind out and warmth in, I use them.


Eye protection.
-Being from Montreal Quebec Canada, I see a lot of hard core winter cyclists and some people definitely prefer ski goggles. They offer exceptional wind protection and many models let you wear prescription glasses underneath.
-I use sports/cycling sun glasses.
-However, sometimes sunglasses are too dark, because it is dark outside and and I use my night-time Plan B: clear safety glasses, the cool-looking ones available at very affordable prices at any hardware stores. I use these for night time snowshoeing in the forest. (like I said, I am from Canada)


Neck:
 -A fleece headband goes great around the neck to seal the top of a vest or jersey from the chilling effect of the cold wind.
-A triangle fleece neck bandanna (i.e. with velcro) (this thing is super versatile) -If much colder, a full knitted neck tube like for skiing.
-I generally do not use a balaclava, however if you are cold and want the full solution, its called a balaclava.


Chest
-Cycling jersey + 2-way zip cycling vest. This combined with Arm warmers gives full coverage against the chilling wind. The two-way zipper cycling vest is extremely temperature adjustable and is essential
-if colder, add a zip-turtleneck-neck base layer garment or a full-sleeve wool cycling jersey.
-I used to use cycling jacket but I found too warm when I am fully warmed up. So jersey for colder temperatures and make sure it is designed to vent moisture, this is not a rain jacket.
 -For more core insulation there is a good assortment of base & mid-layers available from everywhere. Avoid cotton always!
-For precip conditions or colder & you want FULL outer coverage layer, consider buying alpine gear!


Arms
-It is amazing how well arm warmers cut the wind. The key is to kind one that fits your arms and stays in place and does not slide down the arms. Of three pairs of arm warmers I own, only one really is effective. And it was swag from a race I tied for dead last in.


Hands
-Keeping hands warm is one of the big challenges. I have quite a collection of gloves, liner gloves, over gloves, and mittens. For most of the time I use sports-store liner gloves under cycling gloves.
-During warm up I might add fleece over gloves, or three-finger lobster mitts. Sometimes this is obviously too warm, and I adjust down. I often start with over mitts and take them off when warmed up, because it is easy to chill hands at the start and then have to warm your hands back up (misery) vs start to sweat a bit and take off or adjust the outer hand layer.
-Hands are the only body area where I will start off with too much clothing rather than start off a bit underdressed and aiming for perfect once-I am-warmed up set up.
-A wise person once said you should start off riding and be a "little" cold and you are probably perfectly dressed for when you are warmed up 10-15 minutes into the ride. Hands are the exception.


Legs/lower body
-I do not own leg warmers. I wear thin, medium, or heavy tights, if cold I also wear a legs base layer long johns made of stretch synthetic. These come in a variety of thicknesses.
 -Cross-country ski attire works for this pretty good also, and in general the cross-country ski attire parallels the requirements cold weather cycling attire very well.


Feet
-De feet wool socks, heavy weight version. I like de feet brand wool cycling sox a lot. Avoid: if your sox and shoes become too tight from jamming too-thick socks into your regular shoes. Winter footwear often allows extra space for thick socks or extra insulation so if you have a pair of shoes that are a big large... perfecto.
 -Shoe covers or over-booties. Wind blocking is crucial to keeping feet, and all parts, warm. I like heavy weight full coverage versions. I would like these to have a little pouch for putting in chemical hand warmers for active heat generation. The human body when chilled will cut off blood flow to feet hands so it is important to keep them well-covered and prevent chills at all costs.
-I never really used cold weather cycling shoes, they look cool-weather and not real winter weather shoes. I use layers instead.


Other factors - venting sweat
-It is really important to vent sweat. Cycling is an active sport and sweat is constantly being produced. You do not want this sweat building up in your garments.
-Therefore: no sweat-absorbing cotton! No well-sealed rain gear.


Other factors: visibility
-Cycling in colder temperatures means car drivers are not looking out for cyclists, also there is more darkness than in summer, so having an outer layer of high-vis clothing is something I use when out on the roads.
-Also, when one is all-bundled up you are not like in summer and able to turn your head as easily to see all around you, so make sure drivers can see you.


My hands and feet are quite susceptible to getting cold and with the garments above I am comfy down to -10C/20 F.