Castelli Fast Feet 4 Soudal Quick-step 2026 Socks White EU 40-43

There are lots of so-called aero socks out there. But the Castelli Fast Feet 4 Sock has the development and testing to back up the claim. The few socks that have been tested have probably been tested with a static, nonmoving 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 tested it 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.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 airflowSpecifications:- Weight: 53 g- Fit: RaceTechnology:Rosso Corsa:- Our Rosso Corsa label is only applied to the highest-level products we make. Every thread and fiber, every curve and contour is obsessed ab