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Castelli Alpha RoS Jacket



A brilliant deep-winter performer that takes the hassle out of dressing for the cold

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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As an all-in-one winter jacket, the Castelli Alpha RoS is hard to beat. The Italian brand really means it when it calls it the 'Rain or Shine' (RoS – geddit?) jacket, and there's plenty of insulation for when the mercury falls.

  • Pros: Feature-packed, warm, breathable, great fit
  • Cons: Wickedly expensive, care needed when washing

After living with the Alpha RoS jacket for the past month or so when temperatures have dropped well into single figures at times, it has shaken up my perception of how I should dress for this coming winter.

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I've always been a layering kind of guy – donning baselayers, jerseys and jackets in varying combinations to achieve the optimal solution when I head out on cold mornings. It's a faff, and usually wrong by the time I get back in, when either the temperature has risen or it hasn't rained as predicted.

Castelli Alpha Ros Jacket - riding.jpg

You're probably all familiar with that story in some way or another, but if there's one product that I've reviewed in recent times that can legitimately claim to do it all in deep winter, it's the Castelli Alpha RoS jacket.

Castelli Alpha Ros Jacket - back.jpg

It has a two-piece construction – a technical outer layer made from Gore Windstopper 150 fabric, bonded to a fleece inner lining that covers the core. In truth, when I first donned it for the pre-test photoshoot it looked and felt like a bit of an over-complicated and messy design, but the fact is it takes a lot of the complication out of winter layering, and does it to a level that makes the eye-watering £275 asking price bearable, if not quite great value.

Castelli Alpha Ros Jacket - inner jacket worn.jpg

Worn with the 'hatches battened down', so to speak, it's a superb cold weather solution. Worn over the top of just a summer mesh baselayer, it can easily handle 3-5°C, and I actually found myself unzipping the outer fabric zip in order to get a little extra cooling down my front at times despite the breathability of the outer.

Castelli Alpha Ros Jacket - wind flap.jpg

The other way to increase cooling is to either partially or fully unzip the inner lining, allowing more airflow and the Gore outer fabric to do more moisture wicking. You can't take out the lining, so you can't convert the jacket into what would more or less amount to a Perfetto jersey; I always kept it partially zipped in some way to avoid the risk of it bunching up on my back, which meant that when temperatures were getting up beyond 6-7°C, it really was too heavy for the conditions.

Castelli Alpha Ros Jacket - inner jacket.jpg

Assuming you keep it back for the really cold weather, though, it's brilliant, and feature-packed for the job. The collar is tall and articulated with a fleece backing, the sleeves long and cuffs slim to create a seal from the wind, and a dropped tail for additional protection. That tail is elasticated and figure-hugging too, with a tacky Castelli-branded gripper underneath to ensure it sticks in place over your bibs.

Castelli Alpha Ros Jacket - gripper.jpg

The body is nicely slim without being restrictive – we had a large on test, so that's about right even with Castelli's traditionally small sizing – and doesn't leave any noticeable flapping in the wind.

The Gore Windstopper 150 fabric used throughout (with a lighter version of it used for the back panel for added temperature regulation) isn't quite waterproof, but suitably water resistant for showers and road spray, and the outer zip is partially covered to prevent ingress too. For me, that ticks the 'Rain or Shine' tag and covers any weather I'm likely to want to go out in, but if you're expecting genuinely heavy rain for prolonged periods, a dedicated fully-waterproof jacket is probably your best option.

> Buyer's Guide: 20 of the best waterproof cycling jackets

There's added bulk on the wind-facing parts of the arms and shoulders, while the black parts you can see under the arms and on the flanks are made of the same surface fabric, just without as much bulk, helping comfort and breathability. It's a very comfortable jacket to wear (even if you only wear it with a light baselayer) and is very practical too.

Castelli Alpha Ros Jacket - shoulder.jpg

The pockets are deep and easy to reach and get into even with full-fingered gloves on, and they also feature neat laser-cut holes for drainage in the event that you are caught in a serious downpour. Those holes are cut into small reflective tabs, and there's more reflectivity in the shoulder seam taping and Castelli branding too, for front and side-approaching vehicles.

Castelli Alpha Ros Jacket - pockets.jpg

I'm also a fan of the zipped front pocket – very helpful for quick access to keys or a stashed gel when you're fighting the elements and don't want to stop.

Castelli Alpha Ros Jacket - front pocket.jpg

All of this comes together in two very big figures: 522g in a large-sized garment, and that £275 price tag. The thing is, the weight adds to the sense of protection, while the price tag – remarkably – seems fairly justified given the performance and plethora of features on offer. Jackets like Sportful's Fiandre Extreme and any waterproof ones featuring Gore's ShakeDry fabric all price at around this level, but those are definitely wet-weather-specific without the thermal capacity of the Alpha RoS.

Castelli Alpha Ros Jacket - inner jacket stitched.jpg

Its construction is practically flawless – a single loose strand in one of the shoulder joins between the inner liner and outer on our test jacket – and despite the slightly fussy interior, it looks super-smooth and sleek on the outside.

Castelli Alpha Ros Jacket - Gore Windstopper.jpg

You can have it in the red on test, a sleek black or stylish blue, or a higher-visibility orange that really does look the part.

You'll naturally be wanting to take care of your big investment, and will no doubt need to use something like Nikwax's Tech Wash to keep its technical properties in tip top condition. You'll also want to reduce the stress on the internal seams joining the two parts together by zipping up at least the lining when washing. This also helps keep any untangling required to a minimum.

> 30 of the best pieces of clothing to keep you warm this winter

Overall, the Alpha RoS is a winter jacket with the flexibility to be worn in anything from 5°C and lower, in dry conditions and anything short of a proper deluge, with all the features you could ask for. Yes, it's expensive, but if you look after it properly it's going to give many years of excellent service.

If you want an all-in-one winter jacket with a particular focus on cold weather, I'd say the Castelli Alpha RoS is right at the top of the tree.


A brilliant deep-winter performer that takes the hassle out of dressing for the cold test report

Make and model: Castelli Alpha Ros Jacket

Size tested: Large

Tell us what the jacket 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?

Saddleback (distributor) says: "Castelli Alpha RoS - Rain or Shine engineering provides insulation and breathability for cold dry conditions with great protection during wet rides and a superb fit all built into a full specification winter cycling jacket.

"The goal when Castelli started work on the Alpha Jacket was to create a winter jacket that is good as it can be for cold days. A jacket offering supreme comfort and breathability, a jacket that can adapt to changing temperatures and conditions.

"Additionally, they wanted a jacket that if you did get caught in a heavy shower or the day turned for the worst, you would make it back home warm and mainly dry.

"To achieve this Castelli started with the excellent Gore Windstopper 150 fabric offering a barrier against the wind and rain, then added a fleece lining with its own independent front zipper allowing you to control frontal airflow. A large covered vent in the back works alongside this to allow through-flow of air in milder drier conditions.

"While not being a fully waterproof jacket the Alpha use selective seam sealing, double seams and a partially covered front zipper to keep the worst of the weather out."

Tell us some more about the technical aspects of the jacket?


- Gore® Windstopper® 150 fabric is windproof highly breathable and offers great protection from rain and spray

- Seam sealing on the shoulders with a reduced seam main body and double stitching work to keep you dry in all but the worst conditions

- Dual layer Alpha construction separates insulation and protection to create better ventilation, moisture evaporation and breathability

- Articulated Collar for a better fit

- Part covered waterproof YKK® Vislon zipper lays flat and slides easily

- Raw edge waist follows the body contours, lays flat and is low bulk

- Raw edge wrists create a perfect interface with Castelli gloves

- The stretch fabrics combined with the latest advanced patterning creates a close fit on a wide range of body types

- Back ventilation for greater comfort

- Castelli silicone text gripper at waist keeps the jacket from riding up

- Front zippered key pocket - with waterproof zip

- Three large open rear pockets with laser cut reflective drainage patterning

- Sizes Men's S-3XL

- Weight 515 g (Size L, claimed)

- Castelli Comfort Range -5˚ to 10˚C

Rate the jacket for quality of construction:

Aside from just one stray strand in the stitching between the liner and outer, the construction is excellent.

Rate the jacket for performance:

In the conditions it's designed for (anything deep-winter-like, aside from the heaviest/prolonged rain), it's superb.

Rate the jacket for durability:

I can't see it wearing down any time soon.

Rate the jacket for waterproofing based on the manufacturer's rating:

Based on the manufacturers rating, it's really effective. Keep it fresh and clean and well looked after, and showers will bead off the jacket.

Rate the jacket for breathability based on the manufacturer's rating:

An eight here, simply because when the lining is in place breathability gets a little less effective; it's very good, but ultimate warmth is prioritised in the coldest temperatures.

Rate the jacket for fit:

The fit is absolutely perfect, it really is. Slim but not restrictive anywhere (even around the neck, which I sometimes find the limiting factor in some garments). It's perfect for performance-orientated riders.

Rate the jacket for sizing:

Typical Castelli fare coming in slightly smaller than true-to-size, but still ample space for those wanting a large (slim) garment.

Rate the jacket for weight:

Objectively, it's a bit of a beast at over half a kilo, but that does add to the sense of protection and isn't a huge drawback.

Rate the jacket for comfort:

I found it very comfortable – the only time it's less so is when you try to wear it with the inner undone, where it can get a bit bunched up.

Rate the jacket for value:

This is a hard one. It's hugely expensive, but it packs so much performance that – I'd say – it delivers okay value. Look after it and it'll pay you back for seasons to come.

How easy is the jacket to care for? How did it respond to being washed?

Not the easiest with the inner layer, and the need to look after the outer fabric well, but it does come back like new if you do take reasonable care.

Tell us how the jacket performed overall when used for its designed purpose

It's brilliant.

Tell us what you particularly liked about the jacket

Feature-packed, warm, breathable, great fit...

Tell us what you particularly disliked about the jacket

Wickedly expensive, care needed when washing.

How does the price compare to that of similar products in the market including ones recently tested on

I'm not sure there are many that we've reviewed recently that are quite like the Alpha RoS. Jackets like Sportful's Fiandre Extreme ( and any waterproof jackets featuring Gore's ShakeDry fabric all price at around this level, but those are definitely wet-weather-specific without the thermal capacity of the Alpha RoS.

Did you enjoy using the jacket? Yes

Would you consider buying the jacket? Yes, even with this price.

Would you recommend the jacket to a friend? Yes, unless they tend to put their bike away for the coldest months or want a jacket for the wettest weather.

Use this box to explain your overall score

Despite the hefty price, this is a superb outer layer for the coldest weather and I rate it very highly indeed.

Overall rating: 9/10

About the tester

Age: 29  Height: 188cm  Weight: 80kg

I usually ride: Canyon Ultimate CF SL 9.0 SL (2016)  My best bike is:

I've been riding for: Under 5 years  I ride: Most days  I would class myself as: Expert

I regularly do the following types of riding: time trialling, club rides, sportives, general fitness riding

Add new comment


Chris Hayes | 4 years ago

I have the RoS Light, which you could classify as Gabba+.  It's a useful jacket, but not suitable for colder weather (I run cold so sub 9).  I was excited when I saw the links to the RoS offering the jacket at significant discounts - but they are all RoS Lights. CAN YOU MAKE SURE THAT THE LINKS TO THE ADVERTISED GOODS ARE THE SAME AS REVIEWED.  It is irritating.  As is clicking on the links to bike sales only to find that they only have one and it is a 49cm frame.  You'd have to be 5-6 inches shorter than the average Brit to ride that. Or 11.

srchar | 4 years ago

It's expensive but good value. It'll last - mine looks new even though it has done two winters, ten commutes per week (it's really breathable and doesn't stink up). I got it out of the wardrobe yesterday for the first time this year and had forgotten how much I like it.

Rapha Nadal | 4 years ago

Thanks again, srchar.  I'm going to get it, along with some other bits, via our C2W scheme which makes the price a bit easier to swallow!

TheBillder | 4 years ago

Alternatively, Galibier Mistral at £75 kept me warm on Sunday between 1-3 deg and a chilly breeze, with a merino base layer. I actually had to remove my buff, cloth skull cap and (for a few minutes) my gloves to cool down. I do run warm but this was in the slow group with my club, and a fairly flat route to avoid ice on higher roads.

No front zip pocket and no scorpion, but £50 in the bank even on discounted prices. Which is 4 months cake costs for me. Just sayin'

Rapha Nadal | 4 years ago

Thanks srchar.  I'm South Coast based so we don't generally see the coldest of winters and I think the standard ROS may just be an overkill. Do you need any more than a base layer on underneath the Light?

srchar replied to Rapha Nadal | 4 years ago
Rapha Nadal wrote:

Thanks srchar.  I'm South Coast based so we don't generally see the coldest of winters and I think the standard ROS may just be an overkill. Do you need any more than a base layer on underneath the Light?

No, I'd cook if I wore anything more. It really is very warm considering how thin and light it is.

srchar | 4 years ago

I have an Alpha ROS Light, Rapha. I'm in London and find the AROSL (pronounce that however you like) is warm enough for anything below 5C. Above 5C, I wear a Perfetto, and by double figures, I'm in a normal jersey.

I run quite hot and don't hang around.

Rapha Nadal | 4 years ago

I'm looking at getting one of these but have also noticed that there's a "light" version which i think may be more up my street.  Does anybody have any experience on the Light version at all?  

Russell Orgazoid | 5 years ago

Just bought one of these and in the cold snap last week i was very impressed. 3 deg C with a summer base layer......7-8 deg was about it's upper limit for me but i run warm.

Regarding fit, im 5ft8 and 38" chest. 70kg. Medium was perfect and some wiggle room and large was ok if you want a bit more room. My medium Gabba was snugger. Really, really comfy.

I'd say the size guide Castelli give is bang on.

Regarding design and quality.....It's a class apart and despite cost, still worth it on first impressions.

I was never sold on brand loyalty, like some, but this jacket is the best Castelli item I've yet owned.

don simon fbpe | 5 years ago

I do like that, I've always layered and fotunately am unlikely to get too warm as the temp increases during a ride. That means that I never remove layers redering te layering a little pointless. When I say I never get too warm, the Gabba was worn throughtout this summer without overheating..

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