Reviews You Can Rely On

Castelli Free Aero Review

If you want to feel like a racer, or you are a racer and you want another short to add to your quiver, it doesn’t get much better than this short
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castelli free aero bike shorts women review
Credit: Castelli Cycling
Price:  $170 List
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Manufacturer:   Castelli Cycling
By Rebecca Eckland ⋅ Review Editor  ⋅  Aug 20, 2018
  • Comfort and Fit - 30% 7.0
  • Padding and Protection - 25% 8.0
  • Breathability and Fabric - 20% 8.0
  • Durability - 15% 7.0
  • Style - 10% 8.0

Our Verdict

This version of Castelli's Free Aero short is no longer in production as of 2019.
High-quality fabric
Aerodynamic design
Looks "fast"
Italian sizing
If you've never worn a Castelli short, the experience of trying one for the first time is something like this: you've always considered your Honda a nice car, until one day when your wealthy relative lends you their Ferrari. OK, maybe it's not that dramatic, but we're sure you will notice — and appreciate — the Castelli Free Aero short's tailored construction, innovative use of synthetic fabrics, and design that is designed to "cheat the wind." Although testers were skeptical about the claim that the shorts "[…]reduced power output requirements by a claimed 10 watts at 50 kilometers an hour," the design might make you feel fast enough to claim a spot on the podium.

Our Analysis and Test Results

If you've never been on a podium for a cycling race or even considered entering that world, you might not know what you're getting into when you try on the Castelli Free Aero short. Brace yourself: this short does look -and feel - fast.

Performance Comparison

castelli free aero bike shorts women review - while a bike short might not make you faster, it will make your time...
While a bike short might not make you faster, it will make your time in the saddle more enjoyable. Picking the right one is essential, this Castelli model is a fantastic (albeit pricey) choice.
Credit: Rich Staley

Comfort & Fit

The Free Aero short is geared toward performance, which to some, might feel uncomfortable. They fit tight. Don't get us wrong, the short is comfortable, but we're sure the Italian sizing and design will be unlike anything you've tried on before. Several of our testers loved the fit and feel of this short and swore they would never go back to a lower performing model again. Casual riders might not appreciate it as much, though.

castelli free aero bike shorts women review
Credit: Rich Staley

The downside of this racer short is its unique sizing; the short is definitely lower-waisted than other models in this review, and some testers disliked the way the shorts don't hold everything in (i.e., the way the short rolls down, and a belly rolls over the short) like other, more high-waisted models do. We also found that this short ran small—order a size larger than you usually would.

Padding & Protection

The Progetto X2 Air Donna chamois has a name like it has its own zip code, and with good reason: the calibrated chamois offers a detailed geography that's sure to give you padded protection in all the right places. If you examine the chamois close enough (please don't try this while you are riding), you will notice that Castelli has provided an elevation profile printed on top of the chamois itself. Its thickest points (15mm) rest just below your sit bones, where you need it the most. The thinnest chamois "valleys" (right along the seam) are a mere 3mm, keeping the seam away from your tender parts and granting extra ventilation where it is needed most. The Progetto X2 Air Donna is also equipped with "memory"—holding itself in shape, even during the longest ride and even after you ride on it, squash it, wash it, fold it, and put it on again the next day.

castelli free aero bike shorts women review

The phrase "you get what you pay for" applies here. Granted, this is one of the most expensive shorts you can get, but after a long day and hard miles, your backside will be singing your praise.


This short manages a time-tested combination of synthetic fabrics and the patented, female-specific Progetto X2 Air Donna chamois to dish out comfort that also feels "fast." This is due, in part, to the use of specific fabrics in different areas of the shorts: with fabric specific to the waist, crotch, back, and lower legs, it's no wonder these shorts breathe with more ease than you do in the final sprint.

castelli free aero bike shorts women review

In our soak tests, the short performed in the top 50% of shorts in this review. Some testers specifically noted that the fabric used on the back panel of the short (on the iconic Castelli logo) is exceptionally quick to dry. The fabric also manages to be stretchy without pressing or squeezing too hard on the skin, giving the rider that perfect sensation of wicking and support.


Reinforced stitching and high-quality fabric across the back and legs of the short: even after months of rigorous testing, the Free Aero still appears pretty much new. One area that seems more delicate than the rest is the Giro Air mesh leg grippers: the see-through bands definitely distribute pressure over a wider area (thus reducing the look of "sausage leg") but look thin enough that, with time, might fray. The only visible sign of wear following the test period was some pilling on the inner thigh (see photo).

castelli free aero bike shorts women review - despite the high price tag, the castelli free aero short began to...
Despite the high price tag, the Castelli Free Aero Short began to show wear on the inner legs where the fabric rubbed the saddle. We were also concerned with the thin-silicone layer around the legs.

Another caveat to consider with this otherwise excellent short: Castelli only warranties items that are accompanied by proof of purchase and that are not due to "normal wear and tear." It should be noted, though, that these shorts withstood months of hard riding, soak-tests, and multiple washes with only the smallest signs of wear, making it very possible that they've earned their hefty price tag.


The first time our testers put on these shorts, the majority of them said: "Mamma mia, I look good!" As Castelli's top-of-the-line short, the Free Aero has tailored panels contoured to a woman's physique, thin silicone bands around each leg to hold the short in place (with several different color options), and reflective elements on the backs of the legs for those races that stretch into the dusk of late summer nights.

castelli free aero bike shorts women review

Some testers objected to Castelli's logo that appears no less than six times on the shorts. Others who race didn't even notice — our guess is: if you're used to being a moving billboard, what's another six logos?

Best Applications

The Free Aero Short is best suited for cyclists looking for a high-performance short with details that make it look like it's ready for 45-minutes on the criterium race course. While it could get you through a spin class or an hour-long ride, most testers who did not race were put off by the short's many logos and race-ready design. The cost of the short, too, points to its specialized purpose: while the Free Aero could certainly get you through an hour-long spin class, who in their right mind would spend $170 on a short for something that a $50 short could do?


As the most expensive item on our review roster, we expected a lot out of the Free Aero. And, for the most part, it delivered: the short offered performance-ready compression, a highly padded 3D chamois, quality fabrics,m and details that add to the short's visibility. However, at $170, we find the price excessive, especially considering that there are other shorts and bibs out there that performed just as well that cost less. If you are dedicated to cycling, though, whether racing or riding long distances, you may very well appreciate the design and high-quality construction of this very high-performance short.

castelli free aero bike shorts women review - the free aero shorts from castelli offer ample padding and...
The Free Aero shorts from Castelli offer ample padding and protection with its patented Progetto X2 chamois.
Credit: Rich Staley


It's hard to conjure up significant performance disadvantages to choosing the Castelli Free Aero. It hosts features at the forefront of bike shorts technology that truly provide speedy happiness in the saddle. But unless you have extra cash to burn or are giving the race scene a go, we suggest you try other shorts that might save you some coin without cutting into comfort, breathability, durability and other marks of high performance. If you insist on wearing a short, we suggest you try the Louis Garneau Fit Sensor 7.5. If you're willing to try on a bib, you might want to check out the SUGOi RS Pro Bib that offers an equal amount of padding, more protection, and more all-around functionality than this highly-specialized race short.

Rebecca Eckland

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