Castelli Fast Feet 3 Sock

The Castelli Fast Feet 3 Sock is the latest aero offering from the Italian clothing giant. They are a clean, crisp pair of socks, they stay up well and Castelli claims they could save you two watts at 50km/h. More importantly to most of us, they’re comfortable and I think they’re good-looking too.

Aero socks have been around for a few years now, and there are always big claims about the time they can save you, and while I don’t doubt this, it’s all very personal, so I’m not going to say how much faster these socks could make you. That said, Castelli says it has created a moving test rig to simulate a rider’s legs spinning in order to test these.

Castelli says that unlike other brands, it spent time working on moving feet, to actually see what their socks can do for a moving rider. This jig simulated a rider’s movements, which is where the 2 watts figure came from. Though Castelli doesn’t tell you whether that comparison is with other aero socks or a standard cycling sock.

Back to what I can quantify: these socks are comfortable. The way brands go about constructing aero socks can actually make a big difference to their comfort, and Castelli has clearly thought about the material and the positioning of the seams.

The lower section is made from a thin, breathable material, which feels very good against your soles, and it stops your feet from overheating. It’s a reasonably stretchy fabric, with a perforated top and minimal seams.

The seam between the foot section and the upper’s lycra is quite thin and unobtrusive. It didn’t pinch and caused me no discomfort, which isn’t always the case and is a good sign for long rides.

The ribbed lycra aero section is thin, so they’re less sweaty than some other aero socks, and I also found this section comfortable.

The socks are designed for a wide range of temperatures, from 10-38°C (50-100°f).

The polyurethane gripper is thicker and while it can get a little sweaty, it’s very effective at keeping the socks in place.

The left sock came with a large and irritating label, but once I cut that out I found the socks excellent for long-distance rides. The lycra actually feels very comfortable against your skin, and you pretty much forget you’re wearing socks.

I like the clean look too, with minimal branding at the top the only deviation from a plain canvas.

There’s plenty of give when putting these on or off, and they never felt like they might rip – unlike some other aero socks.

When pulling them on, it’s worth spending a while to make sure there are no crumples and that the gripper is totally flat against your leg, to make the most of the aero gains on offer.

I have size 45 feet and tested the largest size XXL socks, which are designed for feet up to 47, which is around size 12. The fit was true and I think they should be good up to the claimed 47. There are two other sizes: S/M and L/XL.

Value

At £37 these are far from cheap, though if you’re looking for another small gain for racing or time trials, and if Castelli’s claims are to be believed, these might be a worthwhile investment.

The Velotoze Aero Socks are a couple of quid cheaper and Sam liked them a lot, though they have a more extrovert design.

Rule 28 was one of the originators of the aero sock and its Aero Sock costs £28. Its socks have also been trusted by some of Britain’s top riders for many years.

Check out our best cycling socks buyer’s guide for more options.

Conclusion

If you’re after some fresh aero socks with a classy, timeless design, then the Castelli Fast Feet 3 socks are a great option. I found them comfortable, I think they look good and they come with aero credentials too. Though only you can decide whether those extra watts are important to you.

Verdict

High-quality, comfortable and good-looking, with added aero claims

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