What Our Gearhead(R) Experts Are Saying:"I wore these on a string of cool morning rides, and they hit exactly the right balance of warm without feeling heavy in my shoe. My feet stayed comfortable the whole way through without ever feeling overdressed."Getting the warmth level right on a cool ride can feel like a guessing game, and Castelli built the Sweetspot 20 Thermal Sock to take the guesswork out completely. We love how the PrimaLoft yarn strikes that balance, warm enough for a chilly start, light enough that feet never overheat once the effort ramps up.