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Castelli 2019: New Free Aero Race 4 bib shorts and Aero 6 Jersey launched + video

All-new bib shorts and jerseys developed with Team Sky now available to buy

Castelli today launches its new Free Aero Race 4 bib shorts and Aero 6 jersey, the Italian company's top-end race-focused clothing that has been developed with Team Sky and will be raced by the British team this season.

Dressing the most successful cycling team in modern history is no mean feat, but Castelli has piled years of experience - it made its first bib shorts in 1979 - into ensuring its latest clothing is ready to meet the demands of the team, and also that of performance-focused cyclists in general who are expected to buy this new kit.

Free Aero Race 4 Bib Shorts

Working with professional teams has long been a valuable aspect of product development for the Italian company. It first introduced the Free Aero bib short in 2007 and it has continued to work with pro teams during the development and evolution of the shorts, the latest partnership being Team Sky since the company took over the sponsorship reins in 2018.

It's a short we've reviewed many times here at and they've always impressed the testers.

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To develop these new shorts every aspect has been updated. They’ve come up with a new chamois, new materials and new construction to ensure the shorts are the best yet. They’ve looked to reduce material as much as possible to promote that freedom of fit, to increase comfort to another level.


A lot of attention was first focused on the new Progetto X2 Air Seamless seat pad, the padded insert always the most crucial element of a bib short. It has always been a highlight of Castelli shorts, but it's been improved. It is now softer and more flexible and topped with a new seamless skin care top layer.

New materials and new construction have been used to ensure the bib shorts have a cleaner and more comfortable fit. The leg openings are all-new, now employing a laser cut opening with a softer and stretchier material. On the inside are vertical silicone stripes which don’t restrict the stretch of the hems for improved fit and comfort.

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The bib straps are intended to do nothing but hold the shorts up, and this has always been a key focus for the Free Aero shorts. This idea has been taken to another level with a minimalist approach, with narrow straps made from a light breathable mesh fabric and a slim back panel. A small pocket for stashing a race radio is a nod to meeting the needs of the professional cyclists.

Aerodynamics is an area Castelli has focused on in recent years and so the shorts are made from fabric with a dimpled surface.

Aero 6 Jersey

To match the new bib shorts is a brand new Aero 6 jersey, the original of which was first introduced in 2009 when Castelli was sponsoring the Cervelo TestTeam, a time when jerseys and aerodynamics didn’t really go hand-in-hand.

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Much of the focus has been on honing the aerodynamic properties for a team obsessed with uncovering every marginal gain. Castelli is claiming a 15 watt drag reduction at 50kph and 3 watts at 40kph. It has supposedly gained this aero benefit by analysing the placement of all the seams and utilising CFD and wind tunnel testing to asses and validate the changes.

Might not sound like much but the professional peloton are regularly hitting these sorts of speeds so it’s not to be sniffed at, even though us mere mortals might struggle to hold those speeds for long on our own. And just in case it needs stating, we have no way of verifying these claims so we can only take Castelli's claims at face value.

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Besides being more aerodynamic, Castelli has also focused on improving comfort. It has looked at the shape of the panels and the placement of the seams and developed a jersey that lays flatter on the body. This also helps it wick sweat more effectively to keep you cooler and drier when cycling in warm weather. The sleeves extend down to the elbow and have a raw-cut edge. A full-length zipper on the front is topped by a minimalist collar design.

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As you’d expect, there are three pockets on the back, above which is a large mesh back panel to ensure good heat management. Castelli has employed a small dropped tail at the back of the jersey to allow it to place the pockets in the perfect location and ensure a really good fit around the waist.

First Ride Impressions

The UK winter weather is far from ideal for testing new bib shorts and summer jerseys, so it was off to Mallorca that I jetted for the launch and where I got to try it out on two rides of a good few hours, including an ascent of the iconic Sa Calobra. The weather was sunny and the temperatures was in the mid-teens so just knee and arm warmers were needed to accompany the new clothing.

Two rides are not nearly enough time to thoroughly asses the clothing and the many changes - I’ve brought it back with me for more in-depth testing on home roads - but it does provide a decent first impression. If a short is not going to be immediately comfortable it's unlikely to improve with time, so first impressions are important with clothing. 

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The idea behind the Free Aero shorts is both to provide enhanced aerodynamics and also a fit that provides total freedom. The first thing you notice is that the shorts are snug. It's a comfortable level of compression without being overly tight, and all the panels sit flush to the body with no ripples or wrinkles. There's enough stretch in the fabrics to ensure the shorts have the flexibility to move with your body and not restrict movement, and comfort over a few hours in the saddle is very good.  The new leg openings work very well. The hems didn’t try and migrate up the legs yet there’s not a hint of excess pressure or irritation from the silicone stripes.

The updated chamois provides impressive comfort. Castelli shorts have never lacked comfort in the saddle and these are no different. There's ample cushioning where you need it most, the top layer is very comfortable against the skin and there's no irritation to detect anywhere around the padded insert. I was comfortable for a few hours on the bike, and there's no reason to suspect longer rides won't be met with similar comfort. 

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As much as the jersey is designed to provide excellent aerodynamics, it’s also claimed to be the company’s most comfortable aero jersey and just as at home on a long ride or sportive as at the pointy end of a WorldTour race. I can’t claim to have even an ounce of the speed capability of a professional rider so assessing Castelli’s aero claims are downright impossible.

What I can say though is that it’s really comfortable. The fit is excellent with the material laying flush all over the body, even around the tricky shoulder and neck area.  The cargo pockets are capacious enough for carrying plenty of food, a few spares and any extra clothing you need for changeable weather, and even when fully loaded, the pockets don’t impact the fit and comfort of the jersey, there’s no sagging at the back or pulling of the fabric around the neck and shoulders.

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First impressions then are very good. We're not looking at radical changes to a proven design formula here, but a host of careful revisions that build on and improve on existing high levels of comfort and performance. Team Sky will be wearing this new outfit this season and you can get your hands on it now, with a variety of colours to choose from. I'll have full and in-depth reviews of the new kit once I've logged up plenty of miles. 

The Free Aero 4 bib shorts cost £150 and the Aero 6 jersey is £110, and they are available now from

David worked on the tech team from 2012-2020. Previously he was editor of and before that staff writer at RCUK. He's a seasoned cyclist of all disciplines, from road to mountain biking, touring to cyclo-cross, he only wishes he had time to ride them all. He's mildly competitive, though he'll never admit it, and is a frequent road racer but is too lazy to do really well. He currently resides in the Cotswolds, and you can now find him over on his own YouTube channel David Arthur - Just Ride Bikes

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