Free 2-Day Shipping on Orders Over $50

Castelli Free Aero Race Bib Shorts - Men's


Item # CST005H

Select options
  • Select options
  • Black/Black Stitching, S ($199.95)
  • Black/Black Stitching, M ($199.95)
  • Black/Black Stitching, L ($199.95)
  • Black/Black Stitching, XL ($199.95)
  • Black/Black Stitching, XXL ($199.95)
  • Black/Black Stitching, 3XL ($199.95)
  • Black/White Stitching, S ($199.95)
  • Black/White Stitching, M ($199.95)
  • Black/White Stitching, L ($199.95)
  • Black/White Stitching, XL ($199.95)
  • Black/White Stitching, XXL ($199.95)
  • Black/White Stitching, 3XL ($199.95)
  • 100% Guaranteed Returns
  • Free 2-Day Shipping
    on orders over $50

Item # CST005H

Tomorrow's industry standard, today.

You'd be forgiven for thinking there's an echo in today's bib shorts market. It seems that Castelli's competitors are always exactly one year behind, suddenly developing the same innovations that featured on Castelli's previous models. So, with the release of the new Free Aero Race Bib Shorts, we're pleased to once again present tomorrow's industry standard, today.

As the name suggests, the Free Aero Race Shorts are designed to cheat the wind, reducing power output requirements by a claimed 10 watts at 50 kilometers an hour. The secret to these gains lies in how the shorts manage airflow across their multiple boundaries and textures — most obviously via the dimpling across the shorts' outer plane. Like with a golf ball or some deep carbon rims, these dimples manage the turbulent lamina of air that runs along the shorts' surface, preventing its premature release into pockets of drag-inducing dead air.

Castelli found itself unwilling to part with the Progetto X2 Air Seat Pad, so it returns with only one, minor change: its surface is softer, which means it now presents a more gentle face to your perineum. It retains its bacteriostatic properties, seamless construction, four-way stretch, and ventilating, perforated foam layer. The perforated viscous comfort inserts also enjoy an encore performance, so your sensitive areas will enjoy riding over all manner of terrain.

Those may be the only returning features of the previous model — not even the materials used were safe from Castelli's obsessive need to tinker. The seat and front of the shorts both feature fabrics designed for durability and cooling breathability, respectively, and the entire body is 30% Lycra for a fit that strikes a balance between compression and unrestrictive movement.

The bibs' wide open, non-stifling design also returns from the previous model, but the bibs themselves now comprise two materials. The straps are mesh 3/4 of the way up, but — like any good domestique — the mesh lets a yolk of Castelli's innovative Carré material summit your shoulders. Carré is a hem-less strap that lies virtually flat against your skin, so there aren't any wind-grabbing, stegosaurus ridges from bib straps bulging out of your jersey. The liminal seam between mesh and Carré is also reinforced, so you don't have to worry about any wardrobe malfunctions while hoisting the trophy on the podium.

Last year's model featured Castelli's upgraded Giro3 integrated grip bands at the hem, but it shouldn't surprise you at this point that Castelli has upgraded these yet again. The new Giro Air has the same perfectly flat, stay-in-place grip, but with less mass, which no doubt contributes to the claimed overall weight loss of 17 grams and definitely reduces the aerodynamic footprint. The new band is wider, almost equaling the length of a typical Euro-slammed road stem, and every square millimeter of the material acts as the gripping agent. No silicone gel print here.

The lower mass means the leg bands are also pretty transparent, which may initially be a turn-off, but will likely take off as it appears in the pro peloton. In this case, it's important to note that "pro" isn't short for "UV protection," so we recommend a bit of sunscreen applied a few minutes before suiting up. As a final touch, Castelli included highly reflective details on the back of the grippers for extra safety, just in case you get caught out at a time when sunscreen won't do any good.

  • Claimed savings of 10 watts at 50kph due to aerodynamics
  • Progetto X2 Air chamois
  • Giro Air leg bands stay in place without the use of silicone

Tech Specs

race fit
Progetto X2 Air
yes, Carré yolk
Leg Gripper:
Giro Air
Claimed Weight:
[size large] 178 g
Recommended Use:
road cycling
Manufacturer Warranty:
1 year

Size chart


Men's Apparel
Chest 36.2in
Waist 31.5in
Hip 37in
Inseam 31.9in
How to Measure:
For best results, take measurements over your underwear.
Measure under your arms, around the fullest part of your chest.
Measure around your natural waistline, keeping the tape a bit loose.
Measure around the fullest part of your body at the top of your legs.
Using pants that fit well, measure the crotch seam to the bottom of the leg.

Reviews & Community


Write a review

    Add a:
  • Photos
  • Videos

No file chosen

Rather attach a photo from your computer?


Product Fit:

Runs smallTrue to sizeRuns large

Add Your Size


Height (ft, in):

Weight (lbs):

Size Purchased:

Only jpg, jpeg, png, gif or bmp files please.

Submit ReviewCancel

Castelli free aero bib

  • Familiarity: I've used it several times
  • Fit: Runs small

This my first bib but I use Castelli products regularly. I am an avid cyclist and average 140-190 a week year round in sunny SoCal. A bit more density in the chamois would be appreciated but this is adequate. Well finished like all.Castelli products. I also use the Pearl Izumi and LG. line.

Avg. ride time: 2h 21m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Stitching failure

  • Familiarity: I've used it several times
  • Fit: True to size

I made the mistake of buying the white version but liked the fit. Good compression in the legs and at 6ft and 170lb the XL is a good fit. However being that these are virtually see through I only ever used them on the indoor trainer. After about a dozen rides and a dozen cold washes the seams in the X2 pad have come apart. Even my cheap Voler bibs are still going after a year and I wear these every week out on the local group rides

Stitching failure

Why did they have to mess with them?

  • Fit: Runs small
  • Size Bought: XL

I really loved the prior editions of these shorts but the 2016 version is a mess and sadly I will have to find a new brand as my go to bib short.
I'm fairly tall at 6'3" and weigh 190 lbs , my thighs are regular sized. I've worn 3 different years-editions of Castelli bib shorts over a period of about 5 years. All were sized XL.
The 2016 version are really poorly designed and sized. The straps are no longer as elastic as they were and pull on my shoulders even when riding. Off the bike , I can't wait to change out of them.
The bib short legs offer too much compression and are uncomfortable. The wider elasticated cuffs on those legs are equally overly tight and create 'sausage leg' - even on my normal sized thigh. Additionally , this combination of tight leg and cuff means the short does not naturally adjust itself to what is the correct position on the rider.
I am a huge Castelli fan , the Progetto X2 pad is still one of the best available but I'd recommend skipping this years model and wait for them to correct the fit.

Agree with your review, also had 2-3 new pairs of aero free per year for a few years. Only got 1 pair this year based on the feedback and it is spot on. Fit is weird. Chamois feels more bunched up, leg length is like 3/4" shorter based on tan line, straps are too tight, ugh. what happened.

Avg. ride time: 1h 36m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

high quality & pro

  • Familiarity: I've used it several times
  • Fit: Runs small
  • Size Bought: large

This are some high-quality, pro-style bibs. The upper is minimalist. The straps are thin (1.75”) and fine mesh. The straps/upper is nothing special although I greatly appreciate that the waist falls right at or below my navel. This is better for warm weather and makes going to bathroom easier. I don’t want to buy bibs that come up any higher. The bottom section is what really impresses me. The fabric is compressive, super-soft, and comfortable. They’re perfect for hot weather. It looks great too. It’s finished with some very effective pro-type leg grippers that do not budge. I’m 5’9” and 152 pounds and in most bibs I wear a medium (Capo, Hincapie, Craft, Gore, Bontrager, PI,) but in these I’m definitely a large. And even in the large the crotch is a little tight. I have no choice but to “dress up” if you know what I mean. Nonetheless, the tight fit in that area keeps your junk in place which is nice. You’ll need to squeeze into these bibs a bit regardless of what size you get but once on they feel like a second skin. They’re designed with aerodynamics and compression in mind. The chamois is fantastic. It might be the best I’ve ever felt. I like the inseam length of these bibs although I wouldn’t want them any shorter. However, I have long legs and often like longish bibs like my Capos. These bibs often sell for $200 but you should be able to find them for $150 which is a more appropriate price. I like these so much that I will be buying another.

Too tight!

  • Familiarity: I've used it several times
  • Fit: Runs small
  • Size Bought: Medium

I'm not a big guy and medium almost always fits the bill for me. But I felt like I was putting on a girdle! I like the materials and chamois but definitely size up!

How long I have waited

  • Familiarity: I've used it once or twice and have initial impressions
  • Fit: Runs small
  • Size Bought: Medium

I have had a couple pair of Castelli Endurance bibs, and I had to wait until at least one pair wore out before I could spring for these. From the details, I am glad I waited. The Progetto X2 is definitely more comfortable! The breath-ability of the mesh on the sides is noticeable the moment you step outside. They fit great and are functionally superior to others. Castelli really does know how to make great products!

One very minor gripe. The new shoulder straps are initially hard to get used to, but that goes away on a ride. It might just have been the comfort and feel of the bibs as a whole that made me forget about it, but it didn't bother me during or at the end of my ride.

Avg. ride time: 7h 38m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Like but cannot keep...

  • Familiarity: I returned this product before using it
  • Fit: Runs small
  • Size Bought: XL

The fabric and craftsmanship is great. Unfortunately, Even sizing up, it's too small. The straps are also too short, and I'm having to return. I'm reluctant to go a full 2 sizes up from the chart, expecting that the shorts themselves will become baggy in an effort to get a strap that won't compress my shoulders down. TOO BAD, otherwise, they seem like they'd be great. Shorter and skinnier riders may benefit from this cut, but @6'0", 210 lbs, and 44Chest, with 34 waist, an XL was still too small for me.

Avg. ride time: 13h 52m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Ummm... these run really small.

  • Familiarity: I've used it once or twice and have initial impressions
  • Fit: Runs small
  • Size Bought: XL

The average sized man in El Salvador (where these are made) must be 5' 4". I purchased an XL because it runs small... I think I should have purchased a XXL. I am 6'2" and 185lb, and these just barely fit... the shoulder straps are tight.

Awkward Fit

  • Size Bought: XXL

XL is way too short in the straps, XXL bunches and rides up, straps are uncomfortable, chamois pad is way too far back. I love the old Free Aero Race in XL, for some reason they changed everything in these.

Excellent quality

  • Familiarity: I've used it once or twice and have initial impressions
  • Fit: Runs small
  • Size Bought: Large

Height 5'11" Weight 185
33 waist 40 hips
Size Large, used 3 times on 1-2 hr rides

I always loved my old free aero shorts more than any other, (much better fit and comfort than my 2 older body paint Castellis), but it was time to renew to newer versions. I ordered 2 of these in a size Large and I'm not sure why people are complaining that they run "too small"...yes, they do run tighter than my older free aeros, BUT it's a good tighter, it takes a few seconds longer to gentle pull them up into place but once they're on the compression and fabrics feel awesome. The feel, and comfort are still fantastic, but with more compression in the legs and much better grips (don't fold up or roll at all) and the straps are the best I've had on any bib. The chamois is great as always, didn't notice any change there. Overall, I highly recommend this bib for people who want lots of compression in the legs and gluteus along w the most lightweight and high tech fabrics you can buy for the money. I'm in Miami and greatly appreciate the ultra light fabrics. Hope they last as long as my older versions but can't comment on that aspect yet ...

Too much wrong to ever be right

  • Familiarity: I returned this product before using it
  • Fit: Runs small
  • Size Bought: Medium

The bib-short fit was very straight. Not enough shape through the hips, upper and mid-thigh. I'm not not as lean as I get, but this fit is unacceptable.

The front section of the chamois pad was twisted. Not obvious when I first slipped them on, but huge lump just sitting on the saddle.

The laser cut yoke of the bib-uppers was notched at the junction of the two straps. Based on the comments from others this looks like an obvious point of future failure.

castelli free aero bibs

  • Familiarity: I've used it several times
  • Fit: Runs small
  • Size Bought: medium

I buy a small in Capo and Giordana, Initially I purchased these in a small; in fact they were so small I put them back in the package unworn and returned them for a medium.
Many Thanks to CC's excellent customer service.
I have a 31in waist, 36in hips, 22 in thighs. The mediums are a perfect fit, very comfortable on and off the bike. They are definitely a "race cut." The bib's material and manufacture are great quality, no problems so far.

Avg. ride time: 4h 14m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Too tight

  • Fit: Runs small
  • Size Bought: Large

I am 6' and 170 lb. 32 waist. The size chart is way too weird which shows between S to M.... So I ordered L but too tight!! Returned it.

yea, i'm same as you. L too tight (height wise) and XL is too baggy...

Very comfortable bib shorts

  • Familiarity: I've used it several times
  • Fit: True to size

Find your dimensions on the Castelli size chart and buy them. They have a very comfortable compression fit when riding. Like most high-end race-fit Castelli clothing, they are designed for riding and not walking around or sitting in a cafe. I'm 5' 11", 32" waist and 38" hips. Medium fits perfectly.

Don't wear well over time

  • Fit: Runs small
  • Size Bought: small

At first, I absolutely loved these bib shorts, but even with careful handling...always washed in a mesh bag, cold water, drip dry, etc...they just didn't hold up. The fabric on the thigh area on both my pairs started to disintegrate, lost the color and became see through. The leg grippers lost their elasticity pretty quickly. For the price of the shorts they should last longer than one riding season. Disappointed.

Same exact thing happened to me. I bought four pairs and took great care of them. The thigh panel pretty much disintegrated. Would have been nice to get a warranty replacement. At $199.00 a pop that's $800.00 worth of what I thought was a high quality product down the drain. I've purchased at least $2,000.00 worth of Castelli product and these were great for a time but in the end proved to be a bad investment. Hope the newer versions are better.

Fixed one problem, created a new one

  • Familiarity: I've put it through the wringer
  • Fit: Runs small

I love the latest version of these bib shorts with the re-enforced seams at the crotch (addressed problem from previous model).

I have two of the prior model and purchased two of the latest model in November 2015 that have the Carré hem-less straps.

Castelli addressed the weak seams at the crotch but introduced a new flaw in the hem-less straps by using the Carré material.

The straps should be laser cut during production to fuse the edges otherwise the material fails overtime like both of mine.

Any slight imperfection will lead to material failure. When I received both of mine, I saw slight nicks in the curved edges but didn't bother to return them until a month later when the tiny nicks got bigger. It's now 5 months later and one has completed separated. See photos.

Fixed one problem, created a new one

Same issue as others

  • Familiarity: I returned this product before using it
  • Fit: Runs small
  • Size Bought: Medium

I have two pairs of Body Paint in size medium and love them so I thought about trying the Free Aero. I was surprised that they were considerably smaller than the Body Paint. I could fit into them but they were a bit tighter than I like. Fit aside the real reason for return was they had the issue in the front of the chamois where it wouldn't lie flat. It appears a portion of the chamois material was folded over and sewn in place. It was only on one side, the other side was fine. So back they went before using them. A bit disappointed.

I had the same problem with two pairs where the pad in front was either sewn in wrong or its just a bad design. It was like riding with an irritating, irregular cotton ball in my nether regions that a healthy application of DZNuts couldn't get rid of. Needless to say I sent both pairs back! I own 3 other bibs from castelli and I love them, Im not sure what the problem is with this version?

Avg. ride time: 3h 39m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

My favorite bib shorts

  • Familiarity: I've used it several times
  • Fit: True to size
  • Size Bought: medium

I own a variety of Castelli bibs, the Evoluzione (Kiss 3 pad), Endurance X2 (bibs and shorts with X2 Progetto chamois), and these Free Aero bibs. While the others do the job, but the Free Aero bibs are the most comfortable and best performing bibs I own. They are comfortable, fit perfectly, the X2 Progetto chamois is just awesome. While I've typically chosen to save $$$ and get the Endurance X2s, I prefer the Free Aero bibs.

best Bibs I own

  • Familiarity: I've put it through the wringer
  • Fit: True to size
  • Size Bought: medium

this is the second pair of these I have. Bought my first pair last year and I fell in love. The chamois is super comfortable. I have done numerous centuries in them and rode them hard all year. They still look great, no pilling or broken seams. sizing is typical European so if you like extra room you may want to size up

Avg. ride time: 2h 40m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Really wanted to like these bibs

  • Familiarity: I've used it once or twice and have initial impressions

I really wanted to like theses bibs. I loved all the materials, the leg bands, the shoulder straps. However, after a few uses/washes the first pair I had developed a problem in the chamois. Part of the chamois pad had become loose between the liner and the lycra near the front of the pad. One email to CC and they quickly and easily sent me a new pair, no problem. The next pair arrived and they had the same issue going right out of the bag. There is no way that there should be loose padding shifting around in the chamois. I definitely feel like Castelli has an issue here. Five stars for CC's customer service though. They are always easy to deal with.

Unfortunately I have had the same problem. Love these shorts, chamois is awesome...until, that is, the front somehow comes loose and folds over between the short material and the chamois cover. Has to be a problem in production, just hope it gets resolved. And yes, Backcountry/Competitive are great to deal with on warranty issues. Always five stars there.

Same problem here. I just sent Castelli an email. Hopefully they are as helpful to me as they were to you.

Mine are the same way. I guess they all suffer from this issue. I kept messing with mine until I got it to lay somewhat flat and even. Now I don't really notice it much, but I still know its there and this definitely shouldn't happen. Whenever Castelli gets this issue ironed out, I'd love to get a second pair. The materials and design are awesome. Kudos to Competitive cyclist for excellent customer service!

Same issue here. Right out of the bag the chamois is detached and folded at the front. I never had this problem with the same type of chamois in my Castelli Inferno bib shorts.