Castelli Nanoflex kneewarmers

Castelli Nanoflex kneewarmers combine two handy functions, keeping your knees both warm and dry. Their only downside is a slightly awkward seam.

Castelli's Nanoflex is a water repellent range of garments based on their Thermaflex material but with silicone filaments added to the surface. These filaments are what keeps the rain out, causing it to bead on the surface and be moved away by the wind.

Heavy drizzle, road spray and riding through fog have little impact on these knee warmers and you'll remain dry for a very long time. Eventually the wet will break through as the fabric gets overwhelmed but it'll take a good soaking before that happens.

Unlike waterproofing treatments the silicone filaments aren't washed away in the washing machine. They are attached to the surface and are part of the material so the performance throughout their life should remain a constant. The care instructions recommend a cool 30 degree wash and not to tumble dry as the silicone isn't a fan of too much heat.

Right then, we've established they'll keep you dry but are the Nanoflex knee warmers worth paying thirty five quid for?

They're Castelli so that does carry a bit of a premium but thankfully they do have the performance to back that up. The fit is very good with a large size staying put on my 55cm upper thigh, a silicone gripper holding the top in place while elastic takes care of the bottom.

The inner is a fleecy lining Roubaix style that is very soft to the touch and keeps your knees warm even when the rain eventually gets through. The Thermaflex fabric does exactly what the title suggests, flexes and moves with your leg while travelling through the pedalling motion.

One whinge though is the seam that runs up the rear. On rides over a couple of hours the seam would start to rub the skin on the back of my knee, which was quite irritating. They aren't articulated at the back of the knee either which does cause the seam to bunch.

Manufacturing wise it's all good. The stitching is good quality and after plenty of wear and machine washes there is no sign of an fraying.

There are three colours available, red, white and black, in sizes from small to extra large.

So are they worth £35? Yes I reckon they are provided that seam doesn't annoy you.

Verdict

Great wet weather performance and wonderfully warm but the seam placement could irritate.