Castelli Ultra Rain Cape review: Fits like a jersey, but lacks waterproofing

The Castelli Ultra Rain Cape aims to be the go-to waterproof in Castelli’s range by combining Polartec® Power Shield RPM waterproof material, the RPM moniker referring to the inclusion of greater stretch, so as to have the fit of a jersey and reduced material flapping. However, as with a lot of post-PFAS-ban waterproofs we have tested lately, the waterproofing performance is not what the old ShakeDry and other PFAS jackets were able to do.

Breathability is exceptionally good for a waterproof, while the fit is ideal for faster paced riding, although it is a bit hard to take on and off while on the move. The waterproofing just needs to continue to improve in this post-PFAS era, but at least elements like breathability are improving.

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Design and specifications

Castelli has designed the Ultra Rain Cape to be packable waterproof jacket but without the usual compromises of flapping material. It has achieved this by using a Polartec® Power Shield RPM fabric which features a two-layer stretch fabric giving it more flexibility and stretch than most standard rain capes. This gives it what Castelli calls a form-fit, similar to a jersey.

Looking at Polartec's website, it states that the Power Shield RPM fabric is waterproof, windproof, highly breathable, stretchy, and made of recycled materials. Waterproof rating is stated as 10,000mm water column, which is the physical height of a water column it can support before it penetrates the material. 10,000 is the minimum value usually necessary for something to be described as 'waterproof'. Breathability is 30,000 g/m²/24h which essentially means how much moisture can transfer through a given area over a period of time. 30,000 is classed as incredibly breathable.

Externally the jacket uses a PFAS-free and PFC-free durable water repellent (DWR) treatment to displace water and bead it off the garment. Seams are then also taped so as to prevent water ingress into the jacket, while the rear of the jacket has been extended to protect more against road spray. Another interesting feature about the jacket is not just the use of recycled fibres, but also the fact that Castelli states the jacket can itself be recycled. It's a nice addition that I’ve rarely seen within the cycle clothing industry where new models or colours are released every season with little thought for what happens to the older garments.

In this Electric Lime colour option, the jacket is designed to be fantastically visible in foul weather. Both this and the black option have reflective piping around the hem and across the shoulders and arms. It’s a surprisingly common thing to see being an afterthought rather than a key feature of a rain jacket and is something I’m a big fan of. Other practical features include a pull tab on the zip to make zipping up and down easier, and the jacket can also pack into its own small internal pocket for easy storage.

Castelli rates the jacket as 5/5 for waterproofing, windproofing, and lightweight on its website, while breathability and insulation are ranked 3/5. Colours available are this Electric Lime, and a standard Black. Sizes range from XS to 3XL.

Performance

Fit wise this is an odd garment by waterproof standards. The material is substantially more stretchy than most hardshell jackets, fitting more like a jersey than a jacket. This means that there is virtually no material flapping even at speed, and makes this likely a far more aerodynamic waterproof than most offerings on the market save for the aero designed Castelli Gabba R. I personally like a more sleek fit, but it does come with a compromise for this jacket. Putting the jacket on when riding is near enough impossible, so tight is the fit of the arms. I had to stop to be able to pull it over my arms, whereas the Gabba R has a short sleeve or a looser forearm fabric making it easier to put on while riding. This is a jacket you have to commit to wearing at the start of the ride really, which is problematic for changeable weather for reasons I’ll explain next.

When it comes to waterproofing, this jacket is an interesting performer. The water column method used is also an interesting one, as water pressure from rain is actually very low. Standing outside in the rain in the Ultra or running it under the tap it was exceptionally waterproof with no moisture transfer inside. The Polartec Powershield fabric working well.

However, driving rain while travelling at speed increases the water pressure, and I found on the front of the jacket in showers the water penetrated through the fabric consistently, save for the reflective tabs which kept it at bay well. At the rear however, the road spray coming off the back wheel didn’t get through the fabric at all, so my back was nicely dry and protected.

There are no front facing seams on the sleeves of the jacket either, so it’s not a case of those being weak points for waterproofing as can happen. Unfortunately, in wetter conditions, the Ultra is just not the best waterproof jacket. It could be the form fitting factor to a degree, as often slightly looser waterproofs mean that the fabric takes some of the pressure from water impact and also makes it slightly more difficult for transfer of moisture through the material if it’s not skintight.

However the old GoreTex ShakeDry did not have this problem (it had a hydrostatic head figure nearly 3x PowerShield), and I’ve not seen it on the equally skintight Castelli Gabba R, which has a lower waterproof rating of just 5000mm. As Will Jones has found in his testing, the spate of new waterproof technologies such as Polartec Powershield fabric do not seem to come close to the ShakeDry tech, may it rest in peace.

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Breathability though is where this jacket really shines. Riding in some 13-17˚C (55-62ºF) temperatures, I normally cook if I wear a waterproof as I run very warm. With a long sleeve jersey underneath, the Castelli Ultra was comfortable even on quite a hilly route with plenty of high intensity low airflow efforts. It’s akin to a semi-thermal jersey in terms of breathability, which is mightily impressive for a waterproof and was quite unexpected.

It achieves this while maintaining solid wind proofing; sometimes the two are not compatible with each other so a compromise is made one way or another. My only gripe on the breathability front is the lack of a two-way zip. If you do get warm, you need to undo from the top which results in some billowing fabric. An asymmetric front zip means it billows on one side more than the other. Plus accessing pockets in the jersey is difficult under the waterproof, especially with that tighter fit.

Other features of the jacket are potentially a bit of a mixed bag. The dropped rear hem is great, as it protects the contents of pockets really well and extends nicely down over the rear. The zip is also decent and can be operated with one hand for opening or closing pretty easily. The off-set nature of it I imagine is to reduce the chance of rain penetration given the lack of flap over the zip. However I find it awkward when you open it slightly, and it looks like the jacket is twisted.

The packable pocket is also more faff than needed, I found it very hard to roll it up into its own self-contained pocket, and instead just shoved it into a pocket with far more ease. It is admittedly very easy to pack up small and stow away.

Two things I am a big fan of are the reflective detailing, and the recyclable nature of the garment. The large reflective strips on the sleeves and shoulder boost visibility really well, and that’s before even mentioning the electric lime colour option which stand out well against almost any backdrop. For riding in rainy or dark weather this visibility is very welcome.

I also appreciate the use of recycled materials and the forward thinking to make the jacket recyclable. Castelli, like all brands now, has made a clear intention to move away from PFAS waterproofing, while also improving the durability and environmental consciousness of its range, and this is something that is good to see in a market where there is often a lot of waste and not much thought into how to limit that or make use of it in future garments.

Value

£240 for a rain jacket is far from being one of the most expensive waterproof offerings on the market, with the new Q36.5 Dottore Rain Jacket being £350 for example. However, in a market where the Gore Wear Spinshift is £224.99 and the rather excellent Rapha Core Rain Jacket is a mere £140 and frankly performs better at waterproofing in my own testing.

Looking at race fit specific waterproofs and the likes of the Pas Normal Studios Mechanism Rain jacket (£250), Rapha Pro Team Gore-Tex Lightweight rain jacket (£295) and Castelli Gabba R (£340) are all either around the same price or a fair bit more expensive. I would say that the Castelli Ultra is, aside from the Gabba R, the most race fitted waterproof option you can get, while being a good chunk cheaper than the Gabba.

Breathability wise is where the Ultra really does win out well. But my problem with that is the waterproofing appears to be compromised, making it hard to justify this as a waterproof jacket. It’s more of a water resistant jersey, but without pockets. My personal preference would be to use a thermal jersey, plus a waterproof gilet to offer most of the protection for rear pockets, with better core waterproofing and similar overall breathability. Given the lack of pockets on the Castelli Ultra, a jersey underneath is not an additional outlay, but rather an essential item anyway.

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Verdict

The Castelli Ultra Rain Cape is less of a cape, and more of a second skin, while it’s also less of a waterproof and more of a shield layer. Its waterproofing is just not good enough in heavier rain conditions when travelling at normal road speeds, although it does provide excellent spray protection at the rear. I like the race like fit and lack of flapping material, while the breathability is superb by waterproof standards.

But this is marketed as a waterproof jacket, and to that end the performance is just not there for most rain conditions. This isn’t like the Castelli Espresso Air jacket, which has been designed explicitly to not be worn in the rain and can therefore be forgiven for the lack of waterproofing. This is a waterproof jacket, that is not very waterproof.