When subfreezing temperatures come to town, the list of your basic needs moves into bold text with lots of underlining. Castelli aims to keep you rolling through harsh, winter base miles, regardless of the conditions with the new Sorpasso RoS Wind Bib Tight, which acts as cycling's equivalent of a windshield and a deep-winter heater. GORE-TEX Infinium Windstopper fabric is sewn into the frontal area and thighs, providing wind protection for your quests down to 23-degrees F. Making up the rest of the RoS Wind is a mix of Nano Flex 3G and Xtra Dry to hold in the warmth while maximizing breathability and water-repellency from passing showers or sleet. Castelli claims these are the best tights fabrics they've engineered, and with sub-freezing protection that also breathes enough to perform up to 46-degree F, we certainly would agree.Castelli uses the performance-tuned Progetto X2 Air chamois to help you with the extended base miles January requires, and the lie-flat bib straps with mesh backing add to the hours-long comfort you'd expect from Castelli. Low-light visibility is enhanced by the reflective calf stripes, which double as zipper guards.