Castelli Socks Fast Feet 4

Description:

Castelli Fast Feet 4 Socks deliver proven aerodynamic performance. Unlike static testing, these socks were developed using a dynamic jig that replicates actual leg movement and verified on real riders. The result: up to 2 watts saved at 50 km/h. The latest version features an updated cuff design for enhanced comfort and aerodynamic efficiency. Built for cyclists who demand measurable speed gains.

Key Features:

• Castelli's Fast Feet project — for maximum aerodynamics
• Foot portion based on Castelli Rosso Corsa Sock for in-shoe comfort
• Polyurethane grip strip at top to keep sock in place
• Leg portion constructed with engineered grooved Lycra® to help detach airflow