"What Our Gearhead® Experts Are Saying: ""This sock has been a game-changer on my cold-weather rides. It’s super warm without being bulky, and the Primaloft stays dry even when I start to sweat. If wool isn’t your thing, this is the perfect alternative."" The Castelli Como 15 Thermal Sock is built for cyclists who want reliable warmth without the bulk—especially when wool isn’t an option. Made with a performance-driven blend of Primaloft® and polypropylene, this sock keeps our feet warm and dry through cold-weather training and long, wet rides. A terry-cloth bottom provides extra loft and insulation underfoot, while thoughtful features like smooth toe seams, directional arch compression, and a reinforced heel keep us comfortable and supported. The 15cm cuff adds coverage and stays securely in place without pinching. It’s everything we want in a winter sock—except the wool."