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CastelliFree Aero Race 4 Kit Bib Short - Men's

Sale 25% Off$149.96 $199.95

Item # CST00S6

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Item # CST00S6

Free Aero Race 4 Kit Bib Short

The professionals on Team Sky had a heavy influence in the construction of the Free Aero Race 4 Kit Bib Short from Castelli. Although most of the riders agreed the existing Free Bibshort was already pretty well dialed, they did request the addition of a loop on the bib to hold a race radio microphone and one rider wanted his chamois shifted back a touch. Apparently, the racers on Team Sky aren't the only ones who like it, the Free Aero Race Bibshort is Castelli's best-selling short, so when it came time for an update, it only wanted to make subtle changes for the better and nothing too drastic. As far as the "Kit" moniker in the title goes, the only difference we can tell over the standard version is the inclusion of color blocking bands at the leg openings.

First up is a new leg gripper that still features a lie-flat, raw-cut edge but now has vertical silicone stripes to hold it comfortably in place without restricting stretch. Next is a new fabric that allows for better print quality and Castelli updated the seams to improve the fit and looks. It also re-engineered the bib straps with new fabrics and construction so they help you stay cooler, lie flat, and are more durable. Finally, it also receives the updated Progetto X2 Air seamless seat insert featuring one of the softest surfaces we've ever felt in a chamois.

  • Castelli's popular racing bib updated
  • Vortex dimpled fabric on the legs offer an aero boost
  • Forza fabric on inner legs stretches for a perfect fit
  • Stripe mesh engineered minimalist bib construction keeps you cooler
  • Doppio V construction in the front increases support and comfort
  • Flat-lock stitching throughout reduces irritation
  • Progetto X2 Air Seamless chamois offers long ride comfort
  • Giro4 leg gripper elastic provides better grip that's distributed over a larger area
Tech SpecsSize
Tech Specs
[face fabric] Vortex dimpled fabric, [inner leg] Forza fabric with 38% Lycra content
spring, summer, fall
Progetto X2 Air
Leg Gripper
Giro4 elastic
Recommended Use
gravel, road cycling
Manufacturer Warranty
1 year


Men's Apparel




















































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.

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First time Castelli buyer

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

This season I bought 3 pair of Castelli brand bib shorts and one pair of long pants for winter riding. I find the quality of everything I purchased to be extremely high. I've now worn these bib shorts twice and they are extremely comfortable and fit well. The pad is the best and most comfortable I have ever worn. The product holds up well after washing. I also bought a pair of the top of the line bib shorts and those are fantastic as well. I considered Assos and Rapha, but the pricing at the time was excellent. Also, have seen many in my riding club wear Castelli, so that was a strong recommendation for me. Glad I bought them. As far as sizing, i usually wear a large in Pearl Izumi & Voler and was told to take an XL. The people I dealt with at Competitive Cyclist were right and I'm happy with the XL. So, remember the sizing runs small. Go up one size for the best fit.


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

Quite impressed by these bibs. Castelli's Free Aero Race shorts have always been a favorite and it looks like these will be at the top of the pile in my closet. Materials are excellent - the Progetto X2 Air chamois has padding in all the right places without excess bulk, the main fabric of the legs is compressive yet lightweight (I expect these will breathe well in summer), and the bib straps seem to lay especially well against my body and are once again quite airy. Usually I prefer seamless elastic bibs (like Giordana uses) but I have no complaints here. Even without the dimpled material on the legs I'm not winning races but it certainly makes me feel fast. Some of Castelli's lesser pieces have had occasional quality issues with the sewing of the seams but construction is excellent here. Lastly the leg grippers are wide and unobtrusive and the inseam length is perfect.

Once again, the fit is compressive to reduce muscle fatigue in hard efforts or on long days. If you're not familiar with Castelli, in general their apparel runs smaller than American brands and sometimes even a bit smaller than European brands. I wear a large bib in Assos, Giordana, and Pearl Izumi's PRO line, I went up to an XL in this for the strap length as Castelli's straps run short and dig into my shoulders in smaller sizes. The XL's straps are perfect and while I was worried that the body of the bib would be loose and baggy, that's not the case at all due to the compressive material. So if in doubt, size up!

The only difference between the Free Aero Race 4 KIT and Free Aero Race 4 is the graphics/logos.