"This carousel displays a list of buttons that updates the main product image when a button is clicked"
Castelli - Nano Flex Plus Knee Warmer

Castelli Nano Flex Plus Knee Warmer

Temporarily Out Of Stock

Don't get too bummed. This item is on the way and will be available for purchase as soon as it rolls into the warehouse.

Can't wait? Consider one of the other Men's Warmers we have in stock.

View Similar Products

Tech Specs

[front] Nano Flex, [rear] Nano Light, DWR treatment
Claimed Weight:
(pair) 102 g
Recommended Use:
Manufacturer Warranty:
1 year

Ignore the weather forecast.

When the forecast is slightly chilly with a chance of drizzle, be proactive about your knee protection with a pair of Castelli's Nano Flex+ Knee Warmers. They'll resist the elements so your tendons stay dry and happy to turn over long, cloud-covered miles.

Nano Flex starts its life as the warm, stretchy Thermoflex fabric used in many of Castelli's winter pieces. It then gains an outer coating of tiny nanofilaments of silicone fiber that create a water-repellent barrier so raindrops and road spray dead up and run off without soaking through. Despite its water-resistant finish, Nano Flex fabric remains highly breathable, keeping you comfortable even when rain falls in the low 60s.

Across the back, Castelli uses a panel of its lighter Nano Light fabric to increase stretchiness behind your knee for full freedom of motion without reducing protection from the elements. In our experience, the previous generation of Nano Flex warmers tend to bunch behind the knee. This is a common ailment in knee warmers, so it's a small price to play for dry joints, but the addition of Nano Light helps to address that common nuisance.

Silicone grippers on both faces of the thigh hem and the inner face of the calf hem keep the warmers in place.

  • Water-resistant cycling warmth for your knees
  • Soft, brushed lining protects against the chill
  • Silicone grip holds hems in place

More Than Knees

  • Familiarity: I've used it several times
  • Fit: Runs large
  • Size Bought: Extra Large

I purchased this set of knee warmers to compliment my Nano Flex bib shorts. I don't ride in the wets often, but figured I could get more cool weather use out my bibs by adding a couple inches on length. At my height and weight these become knickers. They're comfortable, but definitely long on me. My quads are a tick over 24 inches. To get them above my calves, I'd have to wear them like thigh high stockings. Nonetheless, I love the feel. Just beware of Castelli wonky sizing if your not built like a pro.

Very nice knee warmers

  • Familiarity: I've used it once or twice and have initial impressions
  • Fit: True to size
  • Size Bought: Medium

I had an older pair of merino warmers that annoyed me because they simply would not stay up. Not a problem with these -- the warmers extend 8-10 inches up from the bottom of my bib shorts and did not budge during a 2-hour ride. They are also comfortably tight-fitting and soft. I rode for two hours in the low 40s and was fine. I wouldn't hesitate to ride in colder weather with them.

Stay Dry

  • Familiarity: I've used it several times
  • Fit: True to size

I recently got these to replace my old knee warmers and I made the right choice with these! They have a fleece lining that really keeps you warm. I bought these for the water repellent qualities. They aren't waterproof but they keep you dry from the road spray! Overall, you can't go wrong with these.

perfect for Oregon shoulder seasons

  • Familiarity: I've put it through the wringer
  • Fit: True to size

Shield from wind and rain--you can feel rain drops, and I wouldn't call them water proof, but as long as it's above ~38 degrees and I'm putting out watts, I can ride in a full downpour and be okay. Any colder and I go full winter bib, particularly on a short or low intensity ride.. I was a bit surprised how far I had to pull them up (and under my bib shorts of course) to keep them from slipping down, but this also helps keep me warmer than if they only went mid thigh. I pull them nearly to top of thigh and they end ~ 4 inches below my knee. If you have skinnier legs, I would go medium. Used for commuting and training rides. Logged roughly 300 miles on them, mostly on road, some gravel and mud, no signs of wear yet. Easy enough to take off roadside and tuck in jersey pocket.

Water shedn'

  • Familiarity: I've put it through the wringer
  • Fit: True to size

The Nanoflex material does a great job of shedding road spray and light rain. This comes in handy in the spring and fall weather, when dealing with variable conditions. The Nanoflex knee warmers also do a good job in dry conditions, with plenty of breathability.
Fit seems standard. I am 6' tall, 185lbs and the medium fit perfectly.


  • Familiarity: I've used it once or twice and have initial impressions
  • Fit: True to size

These did keep my knees warm when they would stay in place but I had to stop my ride several times to pull them back into position. After eight miles I gave up and took them off. Next ride I will bring Duck Tape along! They fit snug on my legs but maybe they
should fit like my SKINS (very tight). I ordered a large because my legs are
not skinny, maybe I will trade them for
a medium and see how they like my knees then. Update 4.12 Exchanged for a medium and they slipped less.

My Favorites

  • Fit: True to size

I like knee warmers, don't own leg warmers, and these are the best I have of four other brands. Cool stuff, keeps the knees toasty and long enough to keep the thighs warm under your shorts.