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Castelli Free Aero Race bib shorts



Premium bib shorts with high comfort, build quality and attention to detail. Expensive, but if you ride a lot, worth it

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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With the comfortable Progetto X2 insert, very few seams and widely spaced bib straps, Castelli's Free Race Aero bib shorts are exceptionally good.

The Free Aero Race bib shorts have been in Castelli's collection for a few years, but have been constantly developed over the years and benefited from the company's involvement with the former Cervelo Test Team, and now the Garmin-Sharp squad. There's no harder arena to develop products than pro racing, these shorts are a good example of that.

Castelli combine three fabrics in the construction of these shorts. The side panels are made from Energia Micro which has a high stretch factor, the front panel is Breathe Micro to prevent overheating, and the area in contact with the saddle is made from tougher Action Micro fabric. The three fabrics are combined in a very well shaped and cut short, with very few seams, and in particular none in the inner thigh area. This contributes to a great on-the-bike comfort that is up there with the best bib shorts in this price range.

To ensure comfort on hot days, Castelli have moved the bib straps out as far as possible, keeping your chest mostly free of unnecessary fabric. This is ideal when grovelling up mountain cols with the jersey fully unzipped, but it also contributes to a great lack of restriction around on the torso. The bib straps all but vanish; you never notice them when riding.

As is featured on many of their shorts, the Giro3 leg gripper is a real class feature. A 5cm wide band compresses the legs and keeps the shorts firmly and comfortably in place. There's no need for silicone gripper tape here, the shorts just stay put. This also boosts comfort as there's no irritation of the skin. It's simple, but highly effective.

And finally, inside the shorts is the Progetto X2 Air insert, their top-end offering that is also used across their bib short range. It's without doubt one of the most comfortable inserts I've tested, and manages to provide comfort despite a low bulk design. It consists of two layers: a perforated foam top layer to keep you cool, and a padded layer beneath it. The two pieces are free to move and slide over each other which reduces rubbing, contributing greatly to the comfort.

These shorts have been getting a lot of use. I've been wearing them for training rides, criterium races and six-hour slogs, and every time I pull them on I'm reminded just how comfortable and well fitting they are. They are expensive though, but they're better than many shorts that cost a lot more. They work really hard to justify the price, they're packed with clearly thought out features and details that make them a premium product.

Build quality is high, they look good and the comfort is great. I couldn't ask for more from my shorts.


Premium bib shorts with high comfort, build quality and attention to detail. Expensive, but if you ride a lot, worth it test report

Make and model: Castelli Free Aero Race bib shorts

Size tested: Medium

Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?

This short debuted in 2007 but benefits from years of constant refinement, including 4 years of Pro racing testing, as we try new ways to make it better.

Three fabrics provide technical attributes unmatched by others: (1) Action Micro fabric in the saddle contact area provides durability, (2) Energia Micro fabric on the sides and back provides outstanding stretch and excellent re- turn, and (3) Breathe Micro fabric in front provides en- hanced breathability.

Tell us some more about the technical aspects of the product?

Famous free bib keeps your chest free to avoid overheating

No inner-leg seam

Color-matched giro3 single-layer engineered gripper

2 rear reflective inserts

Progetto x2 air seat pad for famous X2 Air comfort and improved air flow

Rate the product for quality of construction:

Build quality is extremely high with very few seams, and three fabrics combined to good effect. These shorts will last a very long time making them a good investment.

Rate the product for performance:

These offer performance of the highest level, which helps to justify the high cost. From the comfortable chamois, to the widely spaced bib straps, the lack of seams, the combination of fabrics, and the leg gripper, everything is very nicely thought out. And that shows in the ride performance.

Rate the product for durability:

So far these are showing no signs of wear and I can see them lasting many years without issue.

Rate the product for comfort, if applicable:

The Progetto X2 Air with its two-layer design offers very high levels of comfort. The shorts themselves are extremely comfortable, with a great fit.

Rate the product for value:

£135 is certainly a lot of money but I feel these shorts do everything to justify that price, they're among the very best bib shorts currently available.

Tell us how the product performed overall when used for its designed purpose

Ticked all the boxes.

Tell us what you particularly liked about the product

The chamois, fit, bib straps and leg grippers.

Tell us what you particularly disliked about the product

Nothing springs to mind.

Did you enjoy using the product? Yes.

Would you consider buying the product? Yes.

Would you recommend the product to a friend? Yes.

Overall rating: 9/10

About the tester

Age: 31  Height: 180  Weight: 67

I usually ride:   My best bike is:

I've been riding for: 10-20 years  I ride: Every day  I would class myself as: Expert

I regularly do the following types of riding: road racing, time trialling, cyclo cross, commuting, touring, mtb,


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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adamq | 10 years ago

Not recommended for anyone without a flat stomach, The "free" bib does a great job of cupping and emphasing even the modest beer belly.

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