Four thin layers in the teens. Short sleeve wicking tee. Long sleeve crew or turtleneck. Second long sleeve layer over that, either thin medium or heavy depending on moisture and wind. Hi VIs windbreaker overall. At 10 f i have a thin nylon balaclava and my ears are covered by my halo headband. I'm also wearing my long cycling pants, and depending on wind and moisture I may have nylon jogging pants over that. Definitely wool socks with cotton socks over them. And also my winter gloves or mittens with or without inexpensive cotton work gloves under. And really that's all I need at 10 f for a 40, or 90-minute commute depending on the amount of snow and wind. I used to dress heavier but would end up sweating and being colder. I'm usually a little chilly for the first 10 to 15 minutes and then delightfully warm for the rest of the ride. This is what I do, as usual your mileage may vary.