I use Sport Hill XC pants. Designed as a cross-country ski pant. IMO, these are your premier winter cycling pant. I use these all winter. Once the regular daily temp drops below 42f I wear these without thermals or anything like that down to 20f. Anything lower, you'll have to add a second layer. They are totally windproof and coldproof. It's amazing how they perform in cold weather. I don't even feel it. They are not cheap, $120us. I found them online cheaper. I own two pair and I've had them for seven years, and I expect to get many more years out of them. Can't say enough good things about these pants. Their ski jackets make an excellent second layer under my Showers Pass that I use as my primary outer shell in winter. Thin, light and warm.