The Castelli Nanoflex Pro Bibtights are a warm (but not windproof) and water resistant choice for the cold weather, offering great breathability and freedom of movement.
We reviewed Castelli's Nanoflex bib tights here on road.cc a couple of years ago and rated them highly. These are even better thanks to extra layers of fabric in strategic areas and an upgraded seatpad.
You might well have heard of Nanoflex before because Castelli uses it extensively across its range. It's the brand's fleecy, stretchy Thermoflex fabric, a warm polyamide/elastane mix that's given a coating of silicone 'nanofilaments'. This makes water roll off the surface rather than soaking in.
That claim might well have your BS detector buzzing, but Nanoflex really works. It doesn't make the fabric waterproof – heavy rain will get through – but you'll stay dry in drizzle, and road spray won't soak in.
The best bit is that Nanoflex doesn't feel like most other water-resistant fabrics, it just feels like a brush-backed Roubaix material – stretchy and breathable. Other brands have similar fabrics.
Compared with the original Nanoflex bib tights that we reviewed (updated Nanoflex 2 bib tights are now available), the Nanoflex Pros have a double layer of fabric over the seat and the centre of the lower back – the area that's right in the firing line of spray from the rear wheel if you don't use mudguards – and also over your quads and knees.
In the past, I've found that water is most likely to get through Nanoflex where it moves, so that extra layer over the knees is welcome. And as well as offering more water resistance, the second layer adds insulation to the most exposed areas at the front of the tights. You definitely notice that, especially in a cold wind when these tights are noticeably warmer than the original version.
The fronts of the lower legs are made from a waterproof fabric that's highly reflective. These areas aren't very breathable but, personally, I don't sweat a great deal through my shins and I don't think anyone else does either, so that's not really an issue.
Castelli gives these a temperature rating of 6-18°C. I feel the cold but I'd never go out in these at 18°C; I'd sweat gallons. I'd say about 14°C would be about the top limit. I agree with 6°C as the lower limit. Below that and I'd want something with completely windproof panels.
The other key feature to talk about here is the Progetto X2 Air seatpad. It really is excellent, with multi-density, multi-thickness foam, viscous padding, and a smooth, perforated layer next to your skin. It performs superbly however long you're in the saddle.
The Nanoflex Pros are finished off with slim, stretchy straps, YKK ankle zips, and silicone grippers that hold them in place well.
Warm, water-resistant tights with great breathability and an excellent seatpad
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road.cc test report
Make and model: Castelli Nanoflex Pro Bibtight
Size tested: Large, Black
Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
Castelli says: "We initially developed our Nano Flex tights to help you get through the occasional rainy day of training. But you asked for more, so here it is: the extreme-duty Nano Flex bibtight. By putting an extra layer over the thighs, knees and bum we're able to significantly increase the rain protection while also blocking a bit more wind. We've made the lower inner leg completely waterproof, since this was usually the first area to soak through with our Nano Flex tights. And because these tights are going to see heavier use, we've also upgraded the seat pad to the Progetto X2 Air, so you're ready for long rides with a high probability of rain."
Castelli lists these features:
* Extra rain protection for long rides in the worst conditions
* Nano Flex base fabric with Nano Flex Light overlays on thighs, knees and rear
* Reduced seam construction
* Waterproof reflective band on inner leg protects against wheel spray
* Progetto X2 Air seat pad
Tell us some more about the technical aspects of the product?
Castelli says this about its Nano Flex fabric: "Exclusively engineered by Castelli, we take our thermal fleecy stretch Thermoflex fabric and coat it with millions of tiny nanofilaments to create the most water-repellent finish ever. Droplets of water stay as spherical balls on top of the fabric or bounce off the fabric without leaving a trace."
Strange as it might seem, ironing the Nanoflex fabric restores its performance; it really works. Castelli has used a sewn on logo around the back, so it won't flake off in the wash. There's a tiny patch of slightly worn fabric on the seating area, presumably where I've got some gritty mud on there while riding in wet conditions.
Castelli's Progetto X2 Air seat pad is, in my opinion, the best out there. The Nanoflex fabric is highly breathable.
These are great tights with or without the water repellency. Add that into the equation, along with the excellent seatpad, and the value is high.
Tell us how the product performed overall when used for its designed purpose
These deliver on their promise to repel water. They're also very breathable, comfortable, and well made.
Tell us what you particularly liked about the product
The water repellency and the seatpad.
Tell us what you particularly disliked about the product
I'd rather the reflectivity on the front of the lower leg was a bit more subtle.
Did you enjoy using the product? Yes
Would you consider buying the product? Yes
Would you recommend the product to a friend? Yes
Use this box to explain your score
These could be your everyday training tights for a large proportion of the UK off-season. Padded bib tights might start at about £50 if you really look around, but you get a lot for the extra money you pay here, including water repellency and an excellent seatpad.
About the tester
I usually ride: My best bike is:
I've been riding for: Over 20 years I ride: Most days I would class myself as: Expert
I regularly do the following types of riding: commuting, club rides, sportives, general fitness riding
Mat has been in cycling media since 1996, on titles including BikeRadar, Total Bike, Total Mountain Bike, What Mountain Bike and Mountain Biking UK, and he has been editor of 220 Triathlon and Cycling Plus. Mat has been road.cc technical editor for over a decade, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a Cambridge graduate who did a post-grad in magazine journalism, and he is a winner of the Cycling Media Award for Specialist Online Writer. Now pushing 50, he's riding road and gravel bikes most days for fun and fitness rather than training for competitions.