Castelli cycling clothing has got to be one of the most admired brands in the industry. The iconic red scorpion seemingly gives you extra juice when you’re wearing it and seems to pass by too quickly when worn by other riders. Well-known for their cold-weather gear, the NanoFlex Bib Knickers add a hefty dose of rain protection on top of cool-weather protection.

Castelli NanoFlex Bib Knickers Features:

  • NanoFlex fabric provides outstanding warmth and stretch with water resistance
  • Minimum seams for maximum water resistance
  • KISS3 pad for all-day comfort
  • Mesh bib straps for breathability
  • Screen-printed Castelli graphic on both legs
  • Rear reflective inserts
  • MSRP: $149.95
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Castelli NanoFlex Bib Knickers Review

Rain, Snow Meet the NanoFlex Bib Knickers

One of the unsung heroes of cycling gear is the knicker. When the weather gets cool or wet, it seems like your knees end up taking the brunt of the cold. You know you’ve been there as your knees feel like they’ve been shoved inside the freezer. Keeping them warm is key to efficient riding and bib knickers are just what the doctor ordered when temps are hanging in the 40’s and 50’s.

Castelli’s NanoFlex fabric takes center stage on these bib knickers as it sheds rain, blocks wind and adds warmth on cold rides. This treatment is infused into the fabric for highly water-resistant performance. Water simply beads up and blows away at speed, thus leaving your legs dry from the outside.

The water just beads up, thanks to the NanoFlex treatment.

The water just beads up, thanks to the NanoFlex treatment.

Not only are these bib knickers excellent for wet weather, they are quite capable down into the 40-degree realm. My morning assaults have started out in the upper 40’s, but after climbing 1500 ft up American Fork Canyon, there are pockets of upper-30’s. The NanoFlex Bib Knickers have been some of the warmest cool-weather bib knickers I’ve tested. During rainy adventures, the water just beads up and warmth is maintained. The only water penetration (and albeit slight) that I experienced was on my backside as the rear wheel flipped a constant stream of water right at it during one rainy ride.

While the design doesn’t feature a multitude of panels to best map the body, the overall cut of these knickers seems to more than make up for it with a comfortable and snug fit. These are really a simple design, all things considered, but the NanoFlex fabric is stretchy without losing its supportive properties. And, since the seams are the weakest link to water resistance, the minimal panel design improves wet-weather performance.

The frontside of the NanoFlex bib knickers maintained their water resistance even after an hour of constant rain.

The frontside of the NanoFlex bib knickers maintained their water resistance even after an hour of constant rain.

The uppers are comfortable and breathable, but do come up a little high up front for easy roadside relief. Worn with or without a lightweight base layer, I loved the fit and function of the bibs. Moving down low, the KISS3 chamois features continuously-variable thickness instead of the multi-density layers found on other bibs. It’s a great chamois that doesn’t overdo the padding yet still provides ergonomic comfort for happy miles in the saddle.

The leg grippers are about 2-inches wide with a simple textured pattern on the back. They stay put perfectly, but my initial rides were a bit too snug on my calves. Subsequent rides were much better — either I found better placement or they stretched slightly. When riding in the rain, the cuffs get saturated with water and become a little cold on the downhill.

The Good

  • Love the weather resistance for both wind and rain
  • Water just beads up — even after over an hour of constant rain
  • KISS chamois has proven comfortable on long rides
  • Comfortable down to the low-40’s
  • Wide leg cuffs have done away with grippy rubber for a more fluid fit

The Bad

  • Leg cuffs were a bit tight on my calves at first (where they naturally sit)
  • When riding in the rain, the leg cuffs get saturated and become cold

The Bottom Line

NanoFlex fabric is worth it when the weather goes South and these bib knickers are some of the most versatile available. Whether you’re looking for a pair for cyclocross season or want a trusty shoulder-season pair of knickers, these are highly recommended.

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About Author

A Seattle native, Jason developed a love for the outdoors and a thing for mountains. That infatuation continues as he founded this site in 1999 --sharing his love of road biking, mountain biking, trail running and skiing. That passion is channeled into every article or gear review he writes. Utah's Wasatch Mountains are his playground.

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