I put 180's F/R this summer and it was a big improvement.
Newer synthetic insulation is so nice.. I use a Patagonia Nano Air or a Black Diamond First Light jackets when it gets below 0, they stay warm even when pretty well soaked with sweat. It's a pleasant change from most everything else I used to have. I tend to run obnoxiously warm, so down to 0 I have just a long sleep lightweight layer and a Patagonia R1 techface hoodie jacket on the upper body. 0 to -10 I add an insulated vest or just one of the mentioned jackets. Below -10 I add the vest back ontop of the jackets.
Downhill skiing? Wow, that's too cold for me! In that case, I am sure you can bike any weather. Fatbike-> DH skiing feels at least 30F warmer due to continuous effort and lower windchill.As far as riding temperatures go, I'm not sure what my limit will be. I expect sub zero F. Skiing, I've been -15F and was fine.
.....but I think the front would benefit from a 180 rotor, the back seems fine.
I put 180's F/R this summer and it was a big improvement.
Downhill skiing? Wow, that's too cold for me! In that case, I am sure you can bike any weather. Fatbike-> DH skiing feels at least 30F warmer due to continuous effort and lower windchill.