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Castelli Nanoflex Pro Bibtight



Warm, water-resistant tights with great breathability and an excellent seatpad

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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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 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. 

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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.

Castelli Nanoflex Pro Bibtight On Bike

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.

Castelli Nanoflex Pro Bibtight StrapBack

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.

Castelli Nanoflex Pro Bibtight Leg

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.

> Check out our guide to the best bib tights and trousers here

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.

Castelli Nanoflex Pro Bibtight Badge

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 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."

Rate the product for quality of construction:
Rate the product for performance:
Rate the product for durability:

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.

Rate the product for comfort (if applicable)

Castelli's Progetto X2 Air seat pad is, in my opinion, the best out there. The Nanoflex fabric is highly breathable.

Rate the product for value:

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.

Overall rating: 9/10

About the tester

Age: 43  Height: 190cm  Weight: 75kg

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 technical editor for over a decade, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. 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 over 50, he's riding road and gravel bikes most days for fun and fitness rather than training for competitions.

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pauldmorgan | 8 years ago

 £95.99 at Evans right now...

Curly | 8 years ago

They look quite good! Pity the lack of reflective at the rear, The Lusso Nitelife thermal bibtights

Look better value and fit great with more reflective panels and Half the price.

tj | 8 years ago

I got a pair of these quite recently and managed to put my finger through the fabric the first time I wore them...Evans/Castelli were very good about taking them back and giving me another pair though, which have been ok, but I have been treating them very gingerly since then....
The pad is great.
They keep road spray and gentle showers off very nicely and I've personally found them quite warm - a recent ride around Loch Rannoch when the garmin was reading -2 and my legs were fine (feet blocks of ice mind).
The reflective patches on the shins are VERY reflective. Steer well away from flash photographers, it's not a good look...

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