Castelli Free Aero RC bib shorts review

Castelli’s Free Aero RC bib shorts are the Italian brand’s latest flagship offering, replacing the Free Aero Race 4.

Designed with WorldTour pros in mind, the shorts are said to “do everything well”, resulting in a product that is claimed to be aerodynamic, comfortable and suitable for hot conditions.

The result? These flagship shorts impress with their excellent fit, open-panel bib straps and Castelli’s tried-and-tested Progetto X2 chamois pad. However, ventilation could be better.

Castelli Free Aero RC construction

Castelli’s aim with the Free Aero Race RC bibs was to simplify the construction of the shorts while improving their performance.

The Italian brand has halved the number of panels used in the lowers from 10 on the outgoing short to five, which also reduces the number of seams. Castelli uses a fabric it calls Forza 2, which is said to be super-light and stretchy, simultaneously supporting and compressing the muscles.

The straps are minimalist, with an open-panel design for increased breathability. Castelli advises a 15 to 35°C temperature range for the shorts.

Interestingly, the legs of the shorts are completely gripper-less, relying on the Forza 2 material to stay in place. Castelli says it achieved this after trying 28 prototypes, and the lack of a gripper is said to improve comfort.

The shorts also include a mesh rear pocket for storage, where a pro would typically store their radio. We mere mortals can use it for food or valuables.

The Free Aero RC shorts use Castelli’s tried-and-tested Progetto X2 Air seamless chamois. This pad is found on all of Castelli’s high-end shorts (with a slightly less sophisticated KISS pad used on its cheaper offerings).

There is a women’s version of the Free Aero RC bib shorts available too, and both men’s and women’s options are available without bib straps for £15 less.

Castelli Free Aero RC performance

I tested the new Free Aero RC shorts in a variety of conditions, from toasty six-hour mountainous road rides in south eastern Sardinia reaching 34°C, through to less exotic roads in the south east and west of England.

I also ventured off-road on gravel escapades, most notably a scorching six-hour gravel ride in the scenic Chilterns, in the UK.

The shorts were tested on a variety of saddles, too, including the Specialized Power Pro Elaston, Fabric Scoop Radius Elite, San Marco Regale and a Fizik Argo.

Smiles for miles

I’ve ridden in plenty of Castelli bib shorts over the years, but never any from the Free Aero range.

The bib straps, which are unique to these shorts, are excellent. They do a great job of keeping the shorts firmly in place and distribute tension across the shoulders really effectively. Castelli gets extra points for integrating ventilation holes into the straps, too.

The Progetto X2 pad is one of my favourite bib short chamois pads and it didn’t disappoint here. It handles road vibrations well and it doesn’t shift out of place.

The lack of a gripper is an interesting touch from the Italian brand and I can’t say I noticed the lack of it while riding, which is probably a plus.

Unlike other shorts, where a silicone gripper can degrade over time, not grip as intended or leave unwanted pressure marks, I haven’t experienced any issues here, so hats off to the brand for achieving its goal.

I also found that the shorts don’t ride up when wearing knee warmers.

The inclusion of a storage pocket is a nice touch, and while the most it can hold is an energy bar and a gel, it’s welcome extra space to store items on longer rides. I forgot about the extra snacks I was storing here whenever I was riding, which can only be a good thing.

I love that the Castelli logo at the rear is sewn on, rather than printed. It’s always a shame when brand logos start to crack over time as the fabric stretches, especially when they’re still fairly new, and I hope Castelli rolls this technology out to all of its future shorts.

My only gripe with these shorts is the ventilation, which is sound but not outstanding. The 15 to 35°C range is quite wide, but I found the shorts warm to ride in at around 23°C.

In the name of testing, I rode these shorts on a sweltering morning in Sardinia, where the temperature reached 34°C by 10am, and the difference between wearing these and a dedicated warm-weather short (Castelli’s now sadly discontinued Inferno) on a similarly searing morning was significant.

Castelli ranks the ventilation as a 4 out of 5, with its lightweight Superleggera shorts (that have replaced the Inferno) rated a 5 out of 5.

I feel the warm more than others, though, so you may be able to ride more comfortably in hotter conditions.

Castelli Free Aero RC vs Assos Equipe RSR S9 Targa

The Free Aero RC bib shorts are priced at £175, which is not an insignificant chunk of change. One of their main rivals is the Assos Equipe RSR S9 Targa, which I recently reviewed and is the Swiss brand’s flagship aero lightweight bib short.

The Assos bibs are priced at £255 – almost one and a half times the price of the Free Aero RCs.

The Free Aero RCs certainly offer two thirds of the comfort compared to the Assos shorts and the bib straps provide more ventilation. I also prefer the lack of a leg gripper over the suction-cup-esque skinGrip silicone grippers on the Assos shorts.

However, I preferred the chamois pad on the Assos shorts and their overall ventilation properties. If I was parting with my own cash, although my wallet would suffer a haemorrhage, I’d probably pay up for the Assos pair.

However, as always, it’s important to caveat that bib shorts are an incredibly personal choice and what works for one person may not work for another. If maximum ventilation isn’t your top priority, or you know the Castelli Progetto X2 pad is your favourite, you may rightly opt for the Free Aero RCs.

Castelli Free Aero RC bib shorts bottom line

The Castelli Free Aero RC bib shorts are an excellent update to the outgoing platform. The compressive construction is impressive, chamois pad comfort is up there with the best bib shorts and I appreciate the small details the Italian brand has clearly sweated over.

It’s ironic how a more simplistic update, rather than further convoluting the design, is the ticket to the success of the Free Aero RCs.

They can't quite live up to Castelli’s claims with regards to ventilation, though. While the ventilated bib straps are excellent, the Forza 2 fabric used for the rest of the short isn’t as breathable.

The Free Aero RCs would be my go-to shorts for temperatures up to around 23°C, but there are better options for hotter conditions. Otherwise, the bib shorts are yet another success in Castelli’s catalogue.