Castelli Nanoflex bib tights

Castelli's Nanoflex bib tights are a water-resistant option for wet and changeable off-season weather, and that means a lot of the time in the British autumn/winter.

Castelli's Nanoflex is clever stuff. It feels like a normal Roubaix-type fabric – it's stretchy, it's warm, it's breathable – but it is also water repellent thanks to a silicone 'nanotechnology treatment'. Water beads up and rolls off the surface. Really, it does.

That's not to say that Nanoflex is entirely waterproof – it's nothing like GoreTex, for example – but I was out on a ride this past weekend, for example, and it started hoofing down. After a few minutes of pretty heavy rain, I glanced down to see thousands of little water droplets on the surface of the Nanoflex tights. Yes, some water had got in, but not nearly as much as would have got through normal tights, so I was a lot drier and warmer than I'd otherwise have been.

The really good bit is that it's all benefit; there's no downside. A hardshell waterproof jacket or overtrousers will stop rain getting in but they'll also compromise breathability to some extent. That's not the case with Nanoflex. It's a lot like a thousand other fabrics used for cycling clothing, just with the added benefit of being water repellent. You're not compromising on other properties here.

We've reviewed plenty of Nanoflex items on road.cc before, so check them out too. We've found that the water repellency will gradually diminish over time but you can restore it to virtually as good as new by ironing the fabric periodically. Honestly! Just don't let anyone catch you ironing your cycling kit. They think you're crazy enough already.

The seatpad is Castelli's own Kiss3 design. It's not their top level pad (that's their Progetto x2 which really is a bit special) but it's still pretty darn good. The Kiss3 looks basic but that's largely because Castelli haven't stuck graphics all over it shouting about the various features. It actually uses two different densities of padding and the thickness varies in different areas too, being at its greatest underneath your ischial sit bones.

The pad is stretchy enough to mirror your movement as you pedal and the soft, brushed microfibre layer next to your skin has an antibacterial treatment. It's a really good pad on the quiet, and I didn't give saddle comfort a second thought even on big weekend rides.

Castelli haven't gone for loads of different panels here '' quite the reverse. Each leg is one piece of fabric with a single seam down the back. I can't say I particularly noticed that in use, and I didn't get any trouble from that seam, even though it's not flat-lock stitched. Castelli say they've kept the seams to a minimum in order to maximise water resistance, and that seems like sound thinking to me.

The bib section is a light, breathable mesh with wide shoulder straps to reduce the pressure, while at the bottom of each leg you get a YKK ankle zipper with a camlock puller that locks in place and a reflective flap that sits over the top.

The ankle grippers, which Castelli call Giro3, are super-stretchy. If you're not wearing overshoes, they sit right against your ankles the same as normal, but you can also position them over the top of overshoes rather than tucking them inside. Why? You don't want the water that the Nanoflex won't let in simply rolling down the outside of your tights and funnelling into your shoes. Again, it's good thinking and it does work.

The Nanoflex tights provide a level of warmth similar to other Roubaix-type tights, with the addition of that water resistance. Castelli give a temperature range for these of 6-18°C. Their guidelines are usually pretty accurate, I reckon, but even I wouldn't be wearing fleece-backed full-length tights at 18°C and I'm famous for getting cold at any opportunity. About 6-14°C, I'd say.

Don't get these confused with Castelli's Fluido bib tights from last year, by the way . Those tights did have Nanoflex panels but they were different in several other ways.

The are also available in a bib knicker (three-quarter length) version for £95, and as bib shorts for £85. We've not used either but they both use the same Kiss3 seatpad.

Verdict

Water-resistant bib tights for wet and changeable conditions; a decent price too.