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Castelli Mens Nano Flex Pro Race Bibshort Black
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Men's Nano Flex Pro Race Bibshort

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Light, cool, and straight out of the future.

Conquer the competition with shorts that do what they're supposed to — hold the seat pad securely in place while otherwise adding as little weight or fabric as absolutely necessary (without being transparent, obviously), and it needs to last a season of hard use. The Castelli Men's Superleggera Bibshort took this and ran with it, elevating these shorts into a crucial element of any ride.

Engineered with a brand-new fabric that utilizes a woven texture rather than knit that shaves 30% in weight for the same level of support and non-transparency. Constructed from a gradient fabric that becomes increasingly lighter the farther down the leg it extends. Featuring a delightfully light leg that weighs in at a mere 90 g/m2, while also maintaining decent durability and excellent abrasion resistance against the saddle. And no need to worry about feeling wighed down after a ride, this material also absorbs around 30% less moisture when you're sweating, guaranteeing the feeling of refreshment even when conquering the Alpe d'Huez. This short doesn't compromise on comfort.

Using top-of-the-line Progetto X2 Air Seamless seat pad, the spectacular striped mesh bibs from the Castelli Men's Superleggera Bibshort and a flat stretch woven leg gripper keeps everything in place. No matter where your bike takes you, ride with style that offers unmatched comfort at an unbeatable, breathable weight.


  • The premium lightweight hot weather short
  • Gradient stretch woven fabric for minimal weight with optimum support
  • Ultralight fabric to reduce weight by up to 50% while improving durability
  • Minimalist stripe mesh bib to minimize weight and keep you cool
  • Integrated gripper elastic with exposed Lycra® to hold leg in place
  • Embossed logos and stretch silicone scorpion heat transfers
  • Progetto X2 Air Seamless seat pad
  • 20°C - 40°C (68°F - 104°F)
  • Incredible lightweight 141 grams

  • Free Exchanges: This product qualifies for free exchanges within the first 60 days after order. We'll cover the shipping both ways for US customers if you need a different size and/or color of this product. Returned product must be in new condition with all labels and packaging. Free exchanges apply only for product in stock or available for backorder.

    B-Stock - This product has one or more B-Stock units available. These units can be purchased at a discount (see option select). B-Stock units were returned from other customers and may have missing or damaged packaging materials. These units are otherwise as new. The full manufacturer warranty applies. Click Here for more information.


    Style Type: Bibs 

    Black - Small

    Mfg PartNum: L20521010-2 

    Black - Medium

    Mfg PartNum: L20521010-3 

    Black - Large

    Mfg PartNum: L20521010-4 

    Black - X-Large

    Mfg PartNum: L20521010-5 

    Black - 2X-Large

    Mfg PartNum: L20521010-6 

    Black - 3X-Large

    Mfg PartNum: L20521010-7 

    Ordered by Most Relevant First
    5 stars
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    1 stars
    Hip to knee warm, cool indeed
    by SWF Rider
    Cycling Enthusiast
    SW Florida
    1 of 1 customers found this review helpful.

    The bib shorts performed as advertise. The material is supple and hip to knee hugged the leg. I would have preferred if the waist area was a little higher, but that would not deter from buying a second Nano Flex bib. Great for your cooler rides.

    Reviewed 3/14/2022
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    1st time Castelli purchase
    by Rick C
    2 of 3 customers found this review helpful.

    1st time trying Castelli, definitely not the last. Fit is perfect. Quality is top notch. I wanted to make an investment since I was spending so much time on the bike. I'm never going to sell my ass short again.

    Reviewed 12/21/2020
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    Thank you for your feedback.
    Warm and Huggy
    by SWF Rider
    Cycling Enthusiast
    SW Florida
    1 of 1 customers found this review helpful.

    This bib short perform as described. The XL fit was snug but not restrictive. a go to bib for cooler temperatures!

    Reviewed 1/14/2022
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    Thank you for your feedback.