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Nano Flex Pro Race Bib Short - Men's

4.666666666666667 out of 5 stars
3 Reviews


Size Chart


Nano Flex Pro Race Bib Short

Castelli knows we can't always ride when it's 70 and sunny, and that sometimes we must venture out into the rain to get the workout done. The Nano Flex Pro Race Bib Short is an evolution of the shoulder-season favorite Omloop Short, with a brushed fleece lining and water-resistant fabric, the Nano Flex provides the weatherproof layer we need to train in brisk conditions.


  • A pro-level bib for variable weather training
  • Nano Flex 3G fabric repels water, while allowing stretch
  • Long inseam provides additional warmth and coverage to keep muscles firing
  • Mesh bib straps lay flat below jersey or jacket
  • Progetto X2 Air insert provides cushion and comfort for long training days
  • Item #CSTZ7DS
Nano Flex 3G
spring, fall
Progetto X2 Air
Claimed Weight
[large] 7.2oz
Manufacturer Warranty
1 year

Overall Rating

4.5 based on 3 ratings

Review Summary

1 Stars - 0 reviews
2 Stars - 0 reviews
3 Stars - 0 reviews
4 Stars - 1 reviews
5 Stars - 2 reviews

Fits True To Size

Screen reader users: the following list provides a visual scale to illustrate the product fit. Please refer to the heading above for the fit type in text.
Runs smallTrue to sizeRuns large

What do you think about this product?


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4 out of 5 stars

November 22, 2021

Great, But Doesn't Last Long

I've put it through the wringer

CONS: * The red pad (AIR2) lasts about a year before it start tearing. I use this all winter rides in NC from Oct nights to April. But even when it tears, it isn't uncomfortable. No stitch rubbing. * The rain guard coating on the leg starts coming up after 2 years and looks like a zombie * Wasn't cheap, but now cheaper b/c of Pro 2 being out. * IDK how important rain repellant is b/c you get wet from rain at the head, shoulders, body and it runs to the crotch anyways. Legs wet, who cares? PROS: * Crotch padding is very comfortable, easily on problem on 100 mile rides, all sorts of weather. Even in the rain, it doesn't make you feel soggy. * Fabric stretches enough for a guy to pee out top or leg w/o the leg fabric becoming out of shape from the stretch. But the stretch remained tight after 2 years. I never used a drier. Always washed, then let air dry. So the tear & rain-guard flaking off was from washing it I guess. Maybe a side-loading washer would be better on this than a top-loading one? Something to think about. I use Large, and this fits exactly as I expect a large to. Thermal inside is what is needed but on really cold nights, a la below 45 degrees, I use 1 to 2 leggings each leg and sometimes wear MTB shorts b/c the cold hits the groin side chilly willy despite the thermals b/c it's not a wind breaker.

Dennis B

Originally reviewed on Backcountry.com

5 out of 5 stars

September 3, 2021


I've used it once or twice and have initial impressions
Size Bought:
5' 5"

These are comfy and warm i finally gave castelli another so far so good

5 out of 5 stars

January 1, 2021

Perfect for cool weather!

I've used it several times
Size Bought:

Great shorts! They are a bit odd at first because of their length (they extend to just over the knees) and because they don't have a gripper, but they really don't ride up, and not even when I wear leg warmers with them. Pad is super comfortable. They're a bit tight to start, but once you break them in, they fit nice and snug (or aero ;). I wear them alone down to maybe 9C (without windchill), and then add leg warmers to go colder, which bottoms out, for me, at 5C (fair-weather, I know...). Beyond that, I don't know how they hold up. NOTE: That's "true to CASTELLI" size, since Castelli usually runs small. But I'm a Medium in every other pro-level Castelli short I own, so it's consistent within Castelli sizing.

Stefan C