Castelli Nanoflex Plus kneewarmers

Castelli has updated its Nanoflex kneewarmers this year. We test whether the new Plus version is as good as the original




  • Extra warmth for in-between days
  • Persistent water resistant coating
  • No seams behind the knee joint in the new Plus version


  • Not cheap for a short tube of fabric
  • Almost as long as a legwarmer

Price as reviewed:


Castelli’s Nanoflex kneewarmers are a staple of my mid-season wardrobe and good for milder winter rides too. I’ve had a pair for over four years and they’re still going strong. Kneewarmers extend the life of your summer shorts for a month or so in the spring and the autumn. Pair them with fleecy shorts and you’ll get another few weeks’ use from them into even colder conditions. And they’re useful even in the summer if you are making cool starts.

>>> Dos and don’ts of winter training (video)

Castelli adds a bonus to its Nanoflex kneewarmers, which are surface treated for water repellency as well as being fleecy. My four year old pair are still water resistant and do the beady-off trick if you put them under a tap, which is pretty impressive after so much use and washing.

Rear insert of Nanoflex Light fabric is flatlocked into the warmers

Rear insert of Nanoflex Light fabric is flatlocked into the warmers

But the only problem I had with the old Nanoflex kneewarmers was the single flatlocked seam up the rear of the leg. Wear them the way Castelli intended and, coupled with the relatively inflexible fabric, I found that they tended to rub uncomfortably after a few hours’ riding. It’s easily enough addressed by turning the warmers through 90 degrees so that the seam is on the inside of the leg and the large, white Castelli logo at the rear. But nevertheless it’s an irritant. Now it’s been addressed by the Nanoflex Plus kneewarmers.

>>> Buyer’s guide to armwarmers

The front of the Nanoflex Plus warmer is made from the same Nanoflex fabric as of old, But at the rear, there are now two flatlocked seams, displaced to the sides of the knee joint. And the rear of the warmer is made from Nanoflex Light fabric. This is far more stretchy than the standard Nanoflex, so in one stroke Castelli has removed the seam at the back and added a lot more flex.

Outer and inner top grippers mean the warmers stay in place well

Outer and inner top grippers mean the warmers stay in place well

And it works really well. I’ve not had any discomfort at the back of the knee and there’s still plenty of warmth and rain protection. Castelli’s kneewarmers are long too, so you can pull them far up your thigh. This stops a gap opening up below your shorts and adds a second layer of insulation to your hard-working thigh muscles. The bottom of the kneewarmers extends almost to the top of my socks, so there’s plenty of lower leg coverage too.

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There’s no gripper at the bottom of the warmers, but at the top Castelli has a silicone band both on the outside and the inside of the opening. This means that the warmers grip the inside of your short legs as well as your thighs, which helps them stay up and avoids a gap with your shorts.

>>> Leg and knee warmers buyer’s guide (video)

Castelli has been really sensible with the Nanoflex Plus kneewarmers, preserving the great qualities of their predecessors while addressing their one weakness, even it that has taken quite a long time to happen. And they are expensive for such a simple piece of kit.


Preserve the excellent warmth, water repellence and fit of their predecessors while removing the uncomfortable rear seam. But they are pricy.


Weight: 85g

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