The Castelli Fast Feet Sock provides an aero advantage for road racing when it's too warm for the faster shoe covers. Castelli takes the leg portion of their TT shoe-cover and stitch it to their most comfortable sock for in-shoe comfort. It's the same as the aero sock Castelli supply to Team Sky, and it's a riders' favourite.

• Castelli's Fast Feet project ?? for road riding in warm conditions
• The sock portion is based on Castelli's Rosso Corsa sock for in-shoe comfort
• The leg portion is constructed with engineered grooved Lycra to help detach airflow