These run about 1-2 sizes short depending on other brand clothing you have. I am 5� 9� 155lbs with a waist of 31� and inseam of 32�. Castelli had me at M, but it was way too tight and I was almost certain I�d rip the fabric if I pulled them past my thighs. Sized up to an L and it fits much better.
Performance wise these work great. Took them out when temps were in the mid 30s and they kept me pretty warm. Took a spill once and skinned my knee, but the fabric surprisingly didn�t rip. But for the sizing these are great winter tights.
I am 6 feet 165 lbs with a 33 in waist and followed the chart. The Medium is way too small, thinking of jumping two sizes up to the XL. Frustrating I need to deal with returns. :(