Twenty centimeters of cuff height puts the Como 20 Thermal Sock firmly in the tall camp—this is a sock designed for cold weather rides where you want full lower leg coverage without resorting to leg warmers. Castelli builds the Como 20 with Merino wool blend construction that balances warmth retention with moisture management, addressing the common problem of synthetic thermal socks that trap sweat and leave your feet clammy by mid-ride.
The Merino content handles temperature regulation in that way wool does naturally—insulating when dry, continuing to insulate when damp, and resisting the odor buildup that makes synthetic socks unwearable after a single use. Castelli adds synthetic fibers to the blend for durability and stretch recovery, since pure Merino socks tend to bag out at the heel and lose their shape over repeated washes. The result is a sock that holds its form through a season of use while keeping the thermal properties that make wool the go-to material for cold weather cycling.
The 20-centimeter cuff provides coverage that extends well above the ankle bone and into the lower calf zone where wind chill hits hardest. This height also means the sock stays put under leg warmers or tights without sliding down and bunching at the ankle—a minor annoyance with shorter socks that becomes a major distraction when you're two hours into a cold ride and constantly reaching down to adjust.... Read More
Castelli designs the Como 20 with anatomical left and right shaping that follows the natural contours of each foot. This isn't marketing speak—asymmetrical sock construction positions seams and padding where they won't create hot spots under cycling shoe pressure points. The toe box in particular benefits from this approach, since poorly placed seams across the top of the toes can cause irritation during the repetitive pedaling motion that puts constant pressure on the forefoot.
The thermal weight positions these socks for temperatures roughly in the 40-55°F range, though individual cold tolerance varies. Below that, you're looking at neoprene overshoes or heated options. Above it, you'll want something lighter. The Como 20 fits that shoulder season window and early morning winter starts where the temperature will climb but your feet need protection for the first hour.
