I live in Wisconsin, and I ride a bike year-round. I don't even own a car. (Did I mention that I have Reynaud's?) these are definitely the best socks I've ever owned. Period. ( . )
They are thick enough that you may want to get shoes or boots that are a half size bigger, but now that I've worn them in the middle of winter, there's no way I'm ever going to go without them again.
  I've tried nike athletic socks with wool socks over them, and that was ok, but these are SO much better. They create so much dead air space around your foot. Seriously, maybe enough to need larger shoes, cause these are like half an inch thick when uncompressed. So it can be quite a tight fit in your regular shoes. But if you want to retain body heat in your toes, this is what I recommend. In fact, I now use my Darn Tough wool socks as a base layer under these. It's a tight fit, though.