Earlier quoted context omitted.
The only cold problems I have with long distance biking in cold weather are caused by poor circulation in my hands and feet. I inevitably get too warm in my core within 15 minutes of commencing biking and start unzipping my outer layer. To keep my head warm, a balaclava and helmet suffices. It's the cold hands that are the worst though; even in thick gloves they still get too cold. I might have to start trying chemic…
There are gloves with electric heaters that you can charge via micro usb.
Note that this is only really a problem below -5C or so; at "merely" freezing I can manage.