Castelli launches “the ultimate equipment to turn your watts into speed”

If you’re chasing every advantage open to you, Castelli says that its new Aero Race 8S jersey and Free Aero bibshorts offer lower drag than anything previously in the range, thanks to cutting-edge fabric design and seams that have been positioned using CFD (computational fluid dynamics).

2025 Castelli Aero Race 8S Jersey (credit: road.cc)

The Aero 8S is said to offer "CdA [coefficient of drag x area] savings of up to 6% over previous aero jerseys" at 40km/h (24.9mph) and to allow you to move at 40.8km/h (25.4mph) rather than 40km/h (24.9mph) for the same power output (Castelli did its testing at the Galleria del Vento del Politecnico di Milano wind tunnel in Milan). That doesn't tell you a whole lot, so we've requested clarity on exactly which jersey is being compared here.

Castelli says that the Aero Race 8S is the fastest jersey it has ever made in terms of aero efficiency, and that includes its Aero Race 7.0 with a Bolero aero base layer worn underneath

2025 Castelli Aero Race 8S Jersey - sleeve detail front (credit: road.cc)

How come? It’s all down to clever stuff like the ribbed fabric that’s used for the sleeves/shoulders, Castelli says, which has been “designed specifically for the greatest aerodynamic advantage at race speeds” (yes, you're absolutely right, it's difficult to see the white fabric on our white mannequin, so we'll chuck in one of Castelli's pics).

Castelli Aero Race 8S jersey sleeve (credit: road.cc)

Castelli tested several iterations of this fabric in the wind tunnel, using different depths and widths of ribbing, and they used it in different configurations before settling on the final design.

Beyond that, Castelli says that it has used CFD for “optimal seam placement”.

2025 Castelli Aero Race 8S Jersey - zip (credit: road.cc)

Castelli says that aero base layers were important a few years ago when jersey fabrics didn't wick as well as they do now. These days, though, a lot of jersey fabrics are as good as base layers in this respect, so it makes sense to make a really fast jersey that performs without the need for a base layer underneath, hence the Aero Race 8S.

We can’t test the jersey’s aero performance here at road.cc, so we’re just reporting the claims.

2025 Castelli Aero Race 8S Jersey - back pockets (credit: road.cc)

The rest of the jersey is smooth and stretchy with elastic at the waist, designed to keep it in place when you have the rear pockets loaded up.

The price? The Aero Race 8S is £169. It’s part of Castelli’s Pro top-tier performance line, as raced in the WorldTour by Soudal Quick-Step, so we’re not talking about a bargain basement option here. It's that sleeve/shoulder fabric that drives the price up; it's expensive to produce.

2025 Castelli Aero Race 8S Jersey - front gripper (credit: road.cc)

If this dazzling white version doesn’t do it for you, the Aero Race 8S also comes in Black, Mocha (brown) and Belgian Blue, and there's a Soudal Quick-Step version too. An Aero Pro 8S Women's Jersey is priced at £175.

The Free Aero Race S bibshorts (£199) are part of the same range and come from the same angle, with aerodynamics front and centre

2025 Castelli Free Aero Race S Bibshort - legs front (credit: road.cc)

The shorts have a series of textured heat stamp stripes on the outside of each leg, and Castelli says that the fabric delivers a 3% decrease in CdA compared with the previous design (again, at 40km/h).

2025 Castelli Free Aero Race S bib shorts detail (credit: road.cc)

Or, for the same power output, you’d move at 40.4km/h (25.1mph) rather than 40km/h (24.9mph), according to Castelli's stats.

2025 Castelli Free Aero Race S Bibshort - chamois (credit: road.cc)

You get Castelli’s excellent Progetto X2 Air Seamless seat pad, lightweight bib straps, and silicone grippers at the ends of the legs.

Castelli describes the Free Aero Race S as “the fastest Free Aero Race Bibshort we've ever created”. Colour options are the same as for the Aero 8S jersey (above).

2025 Castelli Free Aero Race S Bibshort - legs back (credit: road.cc)

The Free Aero Race S shorts are available for women too, in both bib (£189.99) and non-bib (£170) designs. 

We have the Aero Race 8S jersey and Free Aero bibshorts in for review here on road.cc, so standby for our thoughts over the coming weeks.

www.castelli-cycling.com