The Castelli Aero Race 8S jersey is the brand’s top jersey for racing, as used by the Soudal Quickstep and AG Insurance World Tour teams. This latest iteration ditches the dual later system of the Aero Race 7 and Bolero base layer in favour of a single material specifically to improve thermal regulation while keeping aerodynamic performance optimised.
Construction
The sleeves of the Aero Race 8S jersey feature raised strips in the fabric, designed to create turbulence of airflow going over the arms and reduce the wake, and pressure drag, that comes off the back of the arms. It’s a structure commonly used across World Tour level aero garments as often this material pattern is fastest around 40-45kph. Different strip spacings can impact that further and Castelli features slightly wider spacings, which can make it faster at relatively at lower speeds such as 35-40kph.
(Image credit: Future / Andy Turner)
At the rear are three cargo pockets, which sit just above the elasticated hem, aimed to keep the jersey in place even when pockets are full or the jersey partially unzipped. These pockets feature a folded stitch on the top so although they don’t lie flat they are very easy to open while on the fly. A lowered neck hem is also used again for temperature regulation purposes.
Four colours are available, with White, Black, Navy and Mocha. Sizes come in XS to 3XL and sizing is true to size albeit more race fit than some of the other jerseys in Castelli’s range, so a touch tighter.
The ride
This is certainly a hark back to the Castelli race kit of years gone by. By the brand’s own admission they have at times slipped into making a race kit that is a happy medium between absolute peak performance and more general comfort and usability. It’s an interesting one, as for most of us comfort and usability are important things, but for that end Castelli makes the Espresso and Premio Evo lines. The Aero Race is a dedicated piece of race kit.
(Image credit: Future / Andy Turner)
The body is more compressive than recent Castelli aero jerseys, but not quite as corset-like as the jerseys of old. It’s a snug fit, but it is still true to size. Where Castelli has focussed compression is on the sleeves. But this actually improves comfort too, as no silicone grippers are used yet the sleeves stay well in place over the duration of rides.
Castelli has also made the hem of the jersey quite structured so as to work with the sleeves to keep the body of the jersey in place without being overly snug or compressive. I think this is a great balance personally, as although not shrink wrapping for that classic vacuum packed racer look, the jersey actually fits well without excessive pulling of any fabric. Given high intensity efforts require a lot of breathing, this makes the Aero Race 8S comfortable rather than constrictive, and I really like it for that. The hem can get quite warm, but it keeps everything securely in place, which is important from an aerodynamics perspective.
Another area that aims to keep the silhouette tight are the pockets. Even when full, they are a touch narrower than some of the competition, which keeps the frontal area a little smaller without any full pocket spill to the sides. It does compromise space slightly, but in keeping with the mandate for this jersey it focuses on speed and performance. Elastic tops that are folded over don’t lie flat, but are very easy to access and keep the contents secure.
In terms of aero performance, that is hard to judge without quantifiable testing. What I can do is assess the materials and patterns used. Castelli has used a raised strip fabric for this jersey, whereas the previous iteration used a Bolero base layer with raised strips to texture the smooth material on the sleeves of the jersey. That is still commonly used in time trial skinsuits due to working well at higher speeds in general. This new approach however is now commonplace in World Tour aero jerseys such as Santini, Kalas, Pissei, and Rule28. What’s interesting are the finer details, such as the spacing of the strips. Pissei, who supply Tadej Pogačar and his UAE Team, vary the spacing based on the speed the jersey is designed for. For faster speeds, a closer spacing works best, for lower speeds such as climbing, wider spacings are used. Castelli has opted for a slightly wider spacing here, which could suggest being optimised for more realistic road speeds of 30-40kph.
(Image credit: Future / Andy Turner)
Where this jersey truly excels however is breathability. The body of the jersey is a slightly more open structure and near see-through as well. Where this is most impactful though is on the back of the sleeves. Rather than use an aero material all the way around them, Castelli has fitted a highly perforated material at the rear and around the arm pit. This does have a small impact on aerodynamic performance, but it is probably one of the most effective areas to enhance breathability with limited aerodynamic performance. Given the heatwaves in the UK over the 2025 summer, this jersey was more than comfortable in 30˚C+ temperatures, and actually became my go-to hot weather jersey. Given how important keeping cool is for performance in hot weather at high intensity, this jersey really does offer the best balance between aerodynamic performance and breathability for me. Unzipping a jersey ruins the aerodynamic performance, so if racing in hot weather, a jersey with reduced aerodynamic performance but enhanced cooling that negates the need to unzip, will be quicker than a ‘faster’ jersey that requires unzipping to manage thermal load.
It’s all about taking into consideration the full performance picture, and Castelli has done a superb job with the Aero Race 8S. A zip up valuables pocket and zip guard would aid practicality a touch, but would add extra material to a jersey that is near enough perfect for hot weather high intensity riding. It’s a trade-off that I’m willing to take.
Value & conclusion
Impressively, the Castelli Free Aero 8S jersey, even though a World Tour level piece of kit, is what I would call relatively good value when it comes to a well-ventilated aero jersey.
The likes of the Rapha Flaero jersey is £200 / $280, while the Santini Redux has an RRP of £190 / $249. In fact most dedicated aero jerseys with similar technologies and performance targets are more expensive, often £180-200 / $250-300. There are certainly some elements where different jerseys may have an edge such as the MAAP Pro Race jersey having a zip up pocket for keys, or the Santini Redux having zip guards to protect shorts. However, none of these balance fit, breathability, and promised aero performance quite so well as the Castelli does.
Obviously without wind tunnel testing we can’t really say which is fastest, but there are promising tech features on the Castelli which suggest that performance at 30-40kph should be reasonable. The quantifiable features such as breathability and fit are certainly great though, and for £169 / $200 I think that makes this jersey a pretty good value offering
The Castelli Aero Race 8S is a truly fantastic jersey. It uses up to date aerodynamic materials with a fit that is both comfortable but has aerodynamic considerations. On top of that, there have been some breathability features added in that work brilliantly while promising to have less of a negative impact on the aerodynamic performance. In terms of balancing all aspects of the overall performance spectrum; aerodynamics, comfort and temperature regulation, the Castelli Aero Race 8S jersey manages these superbly. The fact it does this at the lower end of the pricing range for high performance aero jerseys is an added bonus.
