Pas Normal Mechanism Pertex Rain Jacket review: Lightweight and breathable wet weather protection

Thunder boomed and lightning broke the sky as the rain hammered down around me, and I thought to myself, "I hope this jacket does its job".

Girona is often regarded as a dream cycling destination, but the first time I went, it just rained like crazy for three days straight. It made for the perfect start to my test period with the Pas Normal Mechanism Pertex Rain Jacket, providing the heaviest rain I've ridden in for years.

The Mechanism Pertex Rain Jacket sits in the Pas Normal Studios line alongside a few other long sleeve protective jackets, but is the only one with 'rain jacket' in the name and is a dedicated wet weather piece, like any of the best waterproof cycling jackets.

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It's a lightweight, thin rain jacket that uses the Pertex Air Shield three-layer membrane to keep you dry in wet conditions and help the jacket breathe. If you're after a more heavy duty layer the brand also makes the Mechanism Shell Jacket, which my colleague, Will, is currently testing.

The retail price is £250 / $310 / €280 and it's available in three colours. I've been testing it since May, whilst in Girona for the Traka and back home in the UK this summer and autumn.

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Design and aesthetics

The Mechanism Pertex jacket is available in three colours and seven sizes. I've been testing the navy version, which you can see in the pictures, but there are black and plum options to choose from as well.

There's the usual large Pas Normal Studios wordmark on the back. I much prefer this version to the triangular PNS logo on the Mechanism jersey.

This is also the lightest rain jacket I've ever used, at 109 grams for a size small. It's lighter than most other rain jackets, including my well-used Endura Pro SL waterproof, and after conferring with Cyclingnews' rain jacket connoisseur Will Jones, we concluded there aren't many rain jackets that we know of which are lighter; one that is lighter still, however, is the super lightweight (and expensive) POC Supreme jacket.

It is indeed lightweight; there just isn't much of it, and that means it packs down very comfortably into a jersey pocket or bag to carry, which is always welcome. I've carried it a lot this summer at home in the UK and abroad.

When it comes to the jacket's primary function, which is waterproofing, it uses the PFAS-free, three-layer Pertex Shield Air Membrane and is constructed from Polyamide. The Pertex membrane was first launched in 2021 and every seam is taped to prevent water ingress, except the stitching of the very bottom of the jacket to the elastic hem at the rear, which means it might get soggy there in time.

Pertex Shield Air uses an electrospun membrane sandwiched between a woven face fabric and fabric backing. The idea being that waterproofing is good, the jacket remains breathable so you don't get sweaty, whilst offering a good degree of windproofing. It's the same membrane used in the very well-reviewed Albion Zoa Rain Shell.

You may have heard that before; it's what most waterproof jackets are trying to do, and there are a few ways to try and do it. There are, of course, lots of rain jacket options on the market, and in the post-PFAS world, we will all need to recalibrate for the not-quite-as-good but crucially greener, non-PFAS chemical DWR rain jacket options like the Rapha Pro Team Gore-Tex Lightweight Rain Jacket.

Pas Normal lists a temperature range of 0-15 degrees for this jacket, though, of course range is going to depend on what you wear it on top of and how you are riding. It is very light and comfortable, which means I have pulled it on to keep me a bit warmer when stopped on warmer days or if the sun has gone in. I pulled it on whilst waiting for a mate to fix a puncture on a cool, shaded descent recently and was glad of it. The very low bulk, soft material and good breathability have made me more inclined to do this than I usually would be with rain jackets.

You can hopefully see from the images that the jacket does have a more fitted cut, and I feel it might get tight over bulkier winter jackets and or additional layers in my size; there isn't the room of some more generously cut rain jackets, for instance. I'm 176cm and wearing a small in the shots.

This continues into the sleeves, the cuffs end where a long sleeve jersey would most of the time and aren't extended in any way like some jackets, this also contributes to the lightweight vibe.

Details-wise, there is a two-way zip to boost temperature control, and a hang loop at the neck, which isn't cut too high and has a soft lining.

Some flap is to be expected from this kind of garment. If you're racing and want skintight, flap-free protection from the rain and spray, look to the Castelli Gabba R.

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Performance

It's best to start with the question that determines if any waterproof cycling jacket is a success: Does it keep you dry?

In my case, the Pertex rain jacket has kept me dry on various wet rides. At home, it's shrugged off showers and road spray without blinking.

The serious tests were in Girona with back-to-back rides with what I would comfortably call torrential rain. One being cut short due to worryingly close thunder and lightning. I, along with my colleagues on the Canyon Grizl launch, was completely soaked on the outside, but I was very keen to peel off the Pertex jacket and see the damage.

The outer fabric didn't wet out; promising, especially for a brand new piece at that point, and there were no catastrophic failures that allowed water to make its way inside. It kept my top half dry and comfortable.

It also did well as I was climbing in the rain, and I didn't feel overly hot and sweaty. We were starting to climb at that 'we better push on here or this is going to get really grim' pace that often materialises on wet or bleak rides, but it performed well in this department for me. The two-way zip will also allow you to regulate temperature when and if needed.

Generally, breathability has been really good. I don't think I've once felt uncomfortable or clammy; the Pertex membrane really does seem to do its job well. I've ended up keeping the jacket on for extended periods when going hard on the road and have remained comfortable.

Back at my hotel post deluge, I carefully took it off and was very pleasantly surprised; the majority of my top half was bone dry. The bottom of the Spatz BurnR2 gilet I was wearing underneath for warmth, however, had gotten saturated, which takes us onto fit.

The cut of the Pertex rain jacket is fairly close; there is some flap, as mentioned, given the kind of garment it is, but unzipped, it sits like a trendy bomber jacket.

It is on the short side, though, and there isn't much tail drop at all, as you can see in the picture below. My gilet sat slightly lower than the jacket, and this meant my inside layer, at the bottom, got wet from rain and spray, and this did migrate up as the water soaked in.

This short rear cut is present on a lot of Pas Normal pieces right now. I would like the rear of the jacket to be just a touch longer. Yes, you could roll or shift up your inner layer to try and keep it out of harm's way, but this seems unnecessary. Mudguards would obviously help massively, and we are all different shapes and sizes, but a waterproof is meant to protect and cover you.

Value

We are looking at £250 / $310 / €280 for this jacket, so it is pretty pricey.

However, it is in line with plenty of other premium waterproofs with named waterproof membranes, certainly most everything in our best cycling waterproof guide.

It is also less than the Rapha Gore Tex rain jacket I'm also testing currently by over $100. I see that jacket as better suited for long, cold, wet rides in winter; it's roomier and heavier in weight with an external pocket.

The construction and quality are there for me. I think you will really love this piece if you want something lightweight and breathable, that in truth doesn't feel a million miles away from a long sleeve jersey, with solid wet weather protection, of course.

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Verdict

I really like pulling this jacket on, I like the styling for starters and the packability, low weight and cut all mean it's unobtrusive and very easy to pull on and off as needed.

It has, apart from the issue I mentioned with the short tail, kept me dry and comfortable in very heavy rain, so a big tick there. Breathability also seems to be very good, and this has led me to pull it on a lot more for warmth or protection from the wind, boosting value.

If you want the best, most capable waterproof jacket for everything a bleak winter can throw at you and for always riding, regardless of the weather, I don't think it will be this piece. If you want something lightweight that can still deal with an awful lot, this good option from Pas Normal, and one to rival the popular Maap Atmos.