Hi! Just got back from Christmas holidays in Norway. Haven't been out biking in the cold, but been walking a lot testing some cold weather gear I picked up "back home". I was skeptical when I saw a climbing/trekking shop advertised a wool bra. I envisaged some scratchy saggy homespun homeknit thing. Not! It's the most comfortable bra I've ever worn. Even comfier than the Playtex 18hr bra. It's by Aclima, and it kept my boobs toasty warm in weather down to -20C (5F), but wicks well and doesn't overheat indoors. Good support too, and even without padded straps no binding. Next trip home I'm getting more of these! I also got some lightweight wool/silk blend underwear that's pretty good in moderate cold, and some duolayer stuff (polyester liner + washable wool top layer) by Devold that is great for extreme cold. The top also has an extra bit of length at the back that I imagine would be handy for biking (why else would bike jerseys have that feature?), though I plan on just doing spin classes through the winter here. Tried biking in the cold one day and though I was warm enough everywhere else it gave me a splitting headache.