There are many so-called aero socks out there. But the Castelli Fast Feet sock has the development and testing to back up the claim. The few socks that have been tested were probably tested in a static, non-moving test because it's easier. But a foot is always in motion, so we created a jig that replicates the movement of the lower leg. And we test on actual riders to verify the results. This sock can save 2 watts at 50 km/h. The newest version has an updated cuff fit for more comfort and aerodynamic gains.
Benefits:
Castelli Fast Feet project - for riding in warm conditions
The foot portion is based on the Castelli Rosso Corsa socks 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
