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Castelli Nano Flex Pro Bib Tights

Sale $129.96 $199.95 35% off

Item # CST008V

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  • Black, S ($129.96)
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Item # CST008V

Go Nano.

Rumor has it Castelli is working on a portable pedal-powered force field that will protect you from rain and wind when you're riding, but it's still in the test phase, so they wheeled out the new Nano Flex Pro Bib Tights to keep you dry while they run through some more R&D. It's a simple, elegant solution to a difficult problem: how do you stay dry when you're riding in a rainstorm?

The obvious answer is "Wear hard-shell rain gear", but that leads to sweating and eventually sogginess. To prevent sweat buildup, Castelli built the Nano Flex from the fabric of the same name, a stretchy, warm, and soft blend of polyester and spandex, and then infused it with silicone nanofilaments, which make the fabric virtually waterproof without inhibiting breathability.  Accordingly, you can wear the Nano Flex Pro on its own when its drizzly or under Castelli's new Tempesta Pants — which are a more traditional rain shell — when conditions are really bad.

On the thighs, knees, and rear, Nano Flex Light overlays provide extra water resistance, while a waterproof and reflective band at the inner leg keeps wheel spray away from your legs and ankles. All the Nano Flex's panels are joined with reduced seams to eliminate bulk and discomfort, and Castelli's Progetto X2 Air chamois keeps you comfortable in the saddle even if the ride is grueling and the weather straight up nasty.

  • Foul-weather cycling tights for staying dry in the rain
  • DWR-treated material repels water while breathing
  • Chamois included for comfort through base miles
  • Reflective details help keep you visible under overcast skies

Tech Specs

[body] Nano Flex (polyster/spandex blend), [thigh, knee, and seat overlays] Nano Flex Lite
yes, Progetto X2 Air
Recommended Use:
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.

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Great if you buy the correct size

  • Fit: Runs small

Castelli is based in the foothills of the Italian Alps (Dolomites). They know Winter cycling.

The brilliance of these bibtights is the waterproof fabric used at the shin. This prevents the constant wheel spray from your front tire from soaking your tights at the leg (then your socks and feet). Cold wet feet are awful.

These tights prevent this! Remember, if you are riding in real rain to wear these tights OVER your waterproof booties.

I can highly recommend the following booties for riding in wet weather: Pearl Izumi WxB, or Castelli Poggio or Castelli Tempesta.

***Sizing:. With Castelli kit, usually size up +1 from your normal street size. Italian sizing is different. Here, size up +2. Trust me, I'm not kidding. They will still be snug in the thigh.

My recommendation really? Buy two sizes. +1 and +2. Keep the ones that fit best. Return the other (with tags on, etc, of course).

insanely small size

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

I'm 6'4" tall and thin (35" waist) about 190lbs. I could barely get the XL on. I am used to Castelli sizing their gear a size or two small, but this was crazy. I couldn't even zip the calf zippers, and I have pretty narrow calves.. Size up one or two sizes... I wanted to like this, but the fit was just crazy.

Yep, go up at least one size from the regular Nano tights.

I just tried them on at a LBS, and could not zip them up, and there is no way you could ever zip them with socks on. Not enough stretch in the one flexible panel. Bad design.

Yes, size up +2. Italian sizing -is- different.

And... @Guy, I don't think it is a bad design. It is a great design. Just no design can fit every body type.

Tip (online shopping reality): Order two sizes. Return the one that does not fit. (Or both if neither fit.) CC has an easy return procedure. Ride dry and happy out there!

FWIW I am a castelli small in everything from gabba jersey to bib shorts. I ordered these in small and they fit fine, calf closure included. 5' 9", 150 lbs.