Castelli Fast Feet 4 – Every Watt Counts

More speed. Less drag. Performance down to the smallest detail.

Discover the Castelli Fast Feet 4, premium aerodynamic cycling socks developed for cyclists and triathletes seeking every possible performance gain.

Part of Castelli's Fast Feet project, they combine a specially designed grooved Lycra upper for aerodynamics, a foot section inspired by the famous Rosso Corsa socks, and a polyurethane grip band to maintain a precise fit during exercise.

Tested in dynamic conditions and on cyclists, the Fast Feet 4 are designed to reduce aerodynamic drag without compromising comfort.

According to tests provided by Castelli, they can save approximately 2 watts at 50 km/h under the brand's test conditions.

Key Features of the Castelli Fast Feet 4

• Aerodynamic design: developed as part of Castelli's Fast Feet project.

• Up to 2 watts saved at 50 km/h: gain reported by Castelli according to its tests.

• Grooved Lycra on the leg: technical structure designed to reduce air resistance.

• Foot section inspired by the Rosso Corsa: comfort and support inside the shoe.

• Polyurethane top band: non-slip support while pedaling.

• New upper finish: improved fit on this fourth generation.

• Race fit: close-fitting to promote aerodynamics.

• Lightweight and breathable construction: suitable for intense exercise.

• Recommended temperatures from 10 to 38°C: ideal for races in mild to hot weather.

An aerodynamic design developed for speed

In competitive cycling, every detail can influence air resistance.

With the Fast Feet 4, Castelli applies its aerodynamic expertise to an often underestimated accessory: socks.

The brand developed a testing method that reproduces the actual movement of the lower leg while pedaling, before validating the results with cyclists.

This approach aims to optimize performance in conditions that more closely represent real-world use.

Up to 2 watts saved at 50 km/h according to Castelli

Castelli states that the Fast Feet 4 can save approximately 2 watts at a speed of 50 km/h.

This result depends notably on the cyclist's position, body shape, speed, and test conditions.

For competitors, it illustrates the benefit of a complete aerodynamic outfit, in which socks help optimize performance.

Grooved Lycra: technology designed to reduce drag

The upper part of the Fast Feet 4 uses Lycra with technical grooves.

This texture is designed to influence airflow around the moving leg and help reduce aerodynamic drag.

The stretchy material also hugs the calf to limit folds and unwanted fabric movement.

An essential element for maintaining a consistent aerodynamic profile during exercise.

An even more advanced fourth generation

The Castelli Fast Feet 4 feature a new design for the upper part of the upper.

Castelli has reworked this fit to improve comfort and aerodynamic performance.

This evolution maintains a precise fit during sustained exercise while limiting sensations of excessive compression.

Rosso Corsa comfort inside the shoe

The foot section uses a construction inspired by the Castelli Rosso Corsa range.

It prioritizes comfort inside the shoe, breathability, and a fit suited to the demands of pedaling.

This design combines an upper dedicated to aerodynamic performance with a comfortable foot section for intense training and competitions.

Polyurethane non-slip band

The Fast Feet 4 feature a polyurethane grip band at the top of the sock.

It helps prevent the upper from slipping during exercise.

The sock thus maintains its position on the calf, promoting both comfort and a consistent aerodynamic profile.

Socks ideal for competition

The Castelli Fast Feet 4 are particularly suited for:

• Road cycling competitions.

• Time trials, subject to the applicable regulations.

• Gran fondos and fast races.

• High-intensity training.

• Triathlons and IRONMAN races when the regulations allow socks during the cycling leg.

• Cyclists who want to optimize their aerodynamic equipment.

They represent an interesting alternative to aerodynamic shoe covers when conditions or regulations do not allow their use.

Castelli Fast Feet 4: equipment designed for triathletes

In triathlon, cycling performance depends on many factors: position, power, equipment, and aerodynamics.

The Fast Feet 4 make it possible to incorporate an additional technical accessory into this pursuit of efficiency.

For long-distance competitions, they can be used on the bike when regulations allow. However, it is important to consider the time required to put them on during transition.

Why choose the Castelli Fast Feet 4 from Triathlon Store?

At Triathlon Store, we know that performance is also built in the details.

The Castelli Fast Feet 4 are aimed at cyclists and triathletes seeking sophisticated competition equipment that combines aerodynamics, lightness, and comfort.

Their technical design and the tests conducted by Castelli make them a relevant choice to complete a performance-oriented outfit.

Castelli Fast Feet 4: because every watt counts.