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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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
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road.cc 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
Aside from just one stray strand in the stitching between the liner and outer, the construction is excellent.
In the conditions it's designed for (anything deep-winter-like, aside from the heaviest/prolonged rain), it's superb.
I can't see it wearing down any time soon.
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.
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.
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.
Typical Castelli fare coming in slightly smaller than true-to-size, but still ample space for those wanting a large (slim) garment.
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.
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.
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
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 road.cc?
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 (https://road.cc/content/review/235234-sportful-fiandre-extreme-jacket) 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.
About the tester
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