Castelli Aero Race 8S Jersey

The Castelli Aero Race 8S Jersey is the eighth generation of the Italian company’s aero offering, with refined fabrics and a precision fit aimed at making it the brand’s most aerodynamic offering yet. While it’s clearly designed to excel in the wind tunnel and under CFD analysis, real-world performance reveals a few compromises, though very good comfort in the right conditions remains a strong point.

For more options, check out our best summer cycling jerseys buyer’s guide.

Features and fit

The Aero Race jersey has been a staple in Castelli’s range for over a decade, and it was among the first aero-optimised jerseys to hit the market. Now in its eighth generation, this latest version claims to be the company’s fastest yet, denoted by the ‘S’ for speed. Castelli says fabric and fit changes have reduced the rider’s CdA (coefficient of drag area) by 6% compared to previous Aero Race iterations.

As with many performance jerseys these days, the sleeves feature a ribbed construction, engineered with CFD (computational fluid dynamics) to optimise seam placement. Despite the clear emphasis on speed, Castelli has still designed the jersey with practicality in mind. You get three standard rear pockets and a full-length front zip with a large, easy-to-grab YKK Vislon puller.

It’s available in four colours: as well as the white version on test here, there’s black, mocha and blue. Sizing spans from XS to 3XL in Castelli’s race-fit cut, offering a snug profile that’s intended to sit close to your skin.

The fabric is exceptionally lightweight and engineered for breathability and cooling. Castelli lists the jersey at 138g, likely for a medium or large, while our size small sample weighed in at a mere 102g.

Fit-wise, it’s exactly what you would expect from a race-focused jersey. I’ve always worn a size small in Castelli’s range, and it remains comfortable here, though according to its sizing guide, which takes chest, waist, and hip measurements into account, I technically fall into the XS category. Even so, I couldn’t imagine sizing down – the small offers a skintight fit that feels suited to the jersey’s purpose.

Initially, checking the fit off the bike, the fit felt good, with sleeves that extend neatly to the elbow in classic aero fashion.

The body length also appears well judged. When I’m on the bike, the jersey sits well with minimal fabric rippling across the front thanks to its high-cut front area on the abdomen. One thing that becomes immediately noticeable, however, is just how transparent the fabric is – whatever you wear underneath will show through quite clearly.

Performance

The thin fabric is also echoed in the recommended temperature range provided, which is 18-36°C. This temperature range is the same as some other jerseys in the Castelli range, including the Espresso and Premio.

The thin fabric was immediately felt, and there is a lot of air flow through the fabric, which makes it pleasant in warm temperatures, and the cooling effect is very noticeable, perhaps also helped by the white coloured fabric. While I find temperature guidelines for jerseys generally overly cautious and narrow, the Aero Race 8S guide feels accurate, and in milder temperatures, even around 15°C, I started to feel cold wearing the jersey.

While I was riding, the sleeves and the front stayed in place throughout, but the rear section tended to move upwards despite having an elasticated fabric with grippy material designed to keep it in place.

The movement happened whether the pockets were loaded or not, and while trying to hold the same position. This didn’t affect comfort at all, but in terms of pure aerodynamic performance, it resulted in a small amount of fabric movement as it didn’t hold the tight, stretched position.

Overall comfort of the fabric is good, and the large zip puller makes it easy to grab and use one-handed while riding. Riding on warm days, the fabric feels good, and while the seams may be CFD-designed for optimal aero performance, they’re also comfortable, and I didn’t have any discomfort at any point of the jersey. The neckline is perfect for the style of riding it is aimed towards, sitting low with no flapping in the wind.

Value

Compared with the Ekoi Racing Outlast jersey recently tested, where that falls short, the Castelli wins – but also vice versa, as the Ekoi jersey features a longer front, shorter sleeves, and an improved rear panel with little movement.

Overall, both are comfortable, and retail prices are similar, though the Ekoi seems to have a permanent price reduction.

While the £169 price may seem expensive, other well-known premium brands push things further, including Rapha with its Pro Team Aero Jersey at £185, and the Assos Equipe RS Asor that’s the same price.

Another specialist aero jersey, the One Aero Jersey from British company Rule 28, is a little cheaper than the above two at £180.

Conclusion

The Castelli Aero Race 8S is very good in almost every respect, with comfortable fabrics and deep, easy-to-access pockets that make it well suited to even the longest rides. It also offers top-tier aerodynamic performance, a superbly comfortable fit, and excellent breathability, making it ideal for fast-paced riding in warm conditions.

While its ultra-light fabric excels in air flow, it feels too cool when temperatures drop below 15°C, so its use is limited, and the rear panel can ride up slightly in use. Still, with thoughtful details and quality construction, it’s a strong option if you’re seeking a race-fit jersey with real-world versatility and are willing to pay for the performance. That said, if absolute aero gains are your top priority, a skinsuit would ultimately be the better option.

Verdict

Comfortable fabrics and construction, with ultra-thin material that excels on the hottest days

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