Sorry, this product is no longer available!
Castelli Free Aero Race 4 Bib Shorts - SS21 is no longer available at Merlin Cycles. However you may find an alternative or updated product below.
Castelli Free Aero Race 4 Cycling Bib Shorts - 2019
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Castelli Free Aero Race 4 Cycling Bib Shorts - 2019Castelli Free Aero Race 4 Cycling Bib Shorts - 2019Castelli Free Aero Race 4 Cycling Bib Shorts - 2019Castelli Free Aero Race 4 Cycling Bib Shorts - 2019Castelli Free Aero Race 4 Cycling Bib Shorts - SS19Castelli Free Aero Race 4 Cycling Bib Shorts - SS19Castelli Free Aero Race 4 Bib Shorts - SS20

This item was discontinued 11th April 2024.

If you require help finding an alternative to this product please contact customer services.

Code:: CS19003010
Castelli Free Aero Race 4 Bib Shorts - SS21
The Free Aero Race 4 Bibshort is Castelli's top race short, which also means that it’s insanely comfortable. The original Free Aero Race Bibshort was first introduced over a decade ago and has logged literally millions of kilometers under the backsides of Castelli's pro riders and has been the best-selling short in the Castelli retail collection.
Over this time the short has undergone numerous updates and improvements in the never-ending quest to create the best short possible. While the basic concept of a minimalist workhorse pro-level comfortable race short remains, every single fabric, component, stitch and construction method has been updated and improved over time.
This fourth generation of the short features the updated Progetto X² Air Seamless seat pad. This pad separates a soft, stretchy skin care layer that moves with your body from a generously padded cushioning layer that replicates the form of your saddle. Eight-hour rides are no problem. Of course the fabrics are premium, made to our specifications by Italy’s best fabric suppliers. The Forza fabric on the inner leg features 38% Lycra® content for perfect fit, while the Vortex fabric on the side panels is dimpled for aerodynamics. And it’s held in place by the latest iteration of our seamless flat Giro leg gripper.
  • Vortex dimpled fabric on legs for aero performance
  • Forza fabric on inner legs with 38% Lycra® content for perfect fit
  • Stripe mesh engineered minimalist bib construction keeps you cool
  • Giro4 leg gripper elastic for better grip distributed over larger area
  • Doppio V construction in front for increased support and comfort
  • Flat-lock stitchingProgetto X² Air Seamless seat pad
  • Weight: 172g


Leszek Rogaczewski The Best cycling bibs.
Benedict Superb product at a great price. Quick dispatch and good communication. Would definitely buy again.
Mr Bembridge These are really good quality as you’d expect from Castelli, excellent fit and comfortable
Pascal Great quality bib shorts. Classic castelli race fit so make sure you follow their sizing chart! Castelli make some of the best quality bibs out there!
Esteban Castelli Free Aero Race bib Shorts are No. 1. There are no substitutes.
Will W Excellent shorts with comfortable pad. Have several pairs and now prefer to Assos. Great value at Merlin
Mr Cels Best Bib shorts I’ve ever owned, good quality materials and stitching. The pad is comfortable throughout 100km+ rides. You only have to be careful to size up enough. I had to go 2 sizes up vs other bib short brands. (I’m 183kg and 2XL fits me well)
Mark Excellent quality bib shorts that fit well, and feel great thanks to the seat pad that I really get on with. Usual caveat about Castelli sizing, but once you find your size with them, their gear is hard to beat for quality and value, especially from Merlin.
Mr Mutlu High quality and fast shipping.I was torn between two sizes and chose the larger one. Size is perfect
Jeremy excellent, pretty snug fit even for castelli. great pad and supportive fabric.
Jimmy One of the best pairs of cycling bibs I've ever worn. Very comfortable, even on longer rides. I'm 182cm and 80kg -- XXL sizing was perfect for me. Highly recommended.
P Jones Comfortable kit. Bib is lightweight but OK. Size up by one. I am usually XL but XXL fit nicely. I am 187cm tall at 94Kg
DIMOSTENES just excellent bib the best for me and great pad
Nine Lives Simply fantstic shorts! I use these regularly and always have a few pairs on the go. They do last extremely well so work out good value. This pair were bought because of the sale and will be kept until an inuse pair really need throwing out. Anyone new to the sizing of castelli might find this useful: I am size S/M on the chart but need a Lg which are a snuck firm fit. Height 5' 9", Weight 148Lb, Waist 30", Thighs 23".
James Only one ride so far, but already as comfy as any other bib short I have tried. Sizing perfect (I find going one higher than normal for Castelli works great) and the price was great from Merlin.
Nick This is my second pair of Castelli Free Aero Race Bib Shorts - the best, most comfortable shorts I have ever worn, even for long days in the saddle
Mr Berridge Bought as an upgrade to cheaper bib shorts. The pad is better but not a game changer. The material used is where you can feel the quality and nice and airy for inside on the turbo!
Jeremy U. Fits very well! Very tight race fit as advertised, happy with my purchase.
Mr Butcher My go to knicks for long rides. They are superb. I've been super comfortable in them all day in all weather.. I highly recommend them. Castelli do make them small so I go a size larger than for other brands.
Geoff Very comfortable, aero and light. I'm 61 kg and take medium.
JL Very satisfied with these shorts. Seat pad is very comfortable and lasts over time. Relatively small size (176 cm 70 kg , size XL fits perfect)
Mr Bell Great pair of bib shorts. Excellent price as they were on offer. Comfortable pad. Fabric tight and supportive on your thighs. Now have two pairs of these. Straps a little narrow for some possibly, but not a problem for me. Would recommend this product.
Mr Badua Great product from castelli. Best riding comfort for hours of riding
Mr Wepfer Better and better with each generation. Great price from Merlin
Ands Excellent fit and quality as you would expect from Castelli. The pad is exceptional and good for very long and tough days on the bike. Highly recommended, particularly for lean guys who struggle finding a good leg fit in other brands.
John My second pair of these shorts. They are so comfortable. First time with these on did a an hour Cat 1 climb in Alps. Still feel great after a long day on the bike.
MZ I usually wear a large or XL, glad I got the XXL as they fit perfectly.
Mr smith Superb fit, excellent pad as well. Some might find the fit a bit tight but it is suppose to be that way - compression fit - very supportive on long rides.
Mr smith Superb performance bibshorts. Very supportive material and excellent pad. Used over 4 hours and no issues.
Mr Armstrong The combined dividend of retirement and lockdown has allowed me to get out on the bike everyday with the added bonus of the loss of many kilogrammes. Always been a big fan of Castelli clothing. Previously a XL now a L. Really comfortable shorts for the turbo and out on the road. A nice snug fit. Just what I expected.
Mr Towers Larger size than usual , now a perfect fit and amazingly comfortable
Simon Really love these shorts. The pad is the best I’ve had (& I’ve tried several top end brands). Fit really well on the bike (& little snug off it, but that’s not what they’re for right!) I’m 6’1 with 31” waist and large fit nice and snug. Decent leg length as well (I prefer my bibs a bit longer and these are spot on).
Mr Smart Very happy with these . High quality short for the price. Merlin competitive as always and fast delivery.
Ian Muir Amazing, fit great and feel good on the bike
Mr Mortimer Very comfortable and close fitting once on. Thin and narrow shoulder straps could be wider. Enjoy the pad very much. Protects the sensitive area very well.
Moumtzis Perfect fit and quality. Very light and breathable.
Mr Fletcher Very comfortable pad - best I’ve used. I’m 170cm and 70kg and am between a large and medium. Legs are very long which is great if you like that, but I’d prefer an option for a 10-15 shorter leg. Only 4 stars as the straps aren’t the best - very thin material between two thicker bands so you can feel it when riding. No big issue and doesn’t rub but my BTwins are better and less than half the price! Worth every penny for the pad though!
Michael Nice & comfy, quality item, I fully recommend