For temperatures at about 15- to 0F (say from -10 to -20C), I tried 2 or 3 pairs of tights, the "triflex" tights (wind stopper in front, and lycra on the back), with underwear (1 or 2 pairs). Still cold.
I think this is because all of them are tight fitting, and they do not trap air, and as I pedal, the layers press to my skin, creating "cold spots". I am not able to find any "loose" pats to be used at these temperaures.
I only have an old and torn huge track pant that does a very good job. I was looking at the rain pants, but I did not tried them (they are designed for rain, that happens at above zero temps!). Ski pants seems too heavy and bulky. Large track pants are VERY large at the bottom.
What pants you use at these temps? They are large or tight fitting? What about breathability?
Any advice will be appreciated.