The Castelli Alpha 150 is an impressive piece of kit that delivers in many ways on its promise to be the ultimate winter jacket but the hefty price tag will be the deciding factor for less committed winter riders.
Before we go any further, let’s all say a big ‘Happy 150th Birthday’ to Castelli. Founded in 1876, the brand originally made clothing for football teams, ballet troupes and then Alfredo Binda, winner of multiple Giro d’Italia between 1925 and 1933.
The release of the Alpha 150 coincides with this milestone and it is a striking piece of kit. On the outside you get Polartec’s new AirCore fabric, designed to deliver exceptional breathability. Made from recycled polyester yarns in a process that is 100% free from PFAS chemicals, it has environmental credentials that are worth shouting about.
The fabric is produced by Polartec and on the website it describes it as a ‘nano-fibre membrane… made using an innovative electrospinning process’.
The more obvious innovation here is an insulating inner layer constructed from Polartec’s Alpha material that aims to offer new levels of breathability and moisture resistance. It’s a fluffy, mesh-woven fabric that really is very good at dealing with moisture.
I first encountered it when testing a pair of Santini Alpha Undergloves earlier in the year. They were very breathable, added great warmth and dried exceptionally quickly. (You can read why I only scored it 5/10 here.)
On the Alpha 150, this sewn-in gilet can be zipped up separately. And using this in conjunction with the top and bottom opening YKK zipper on the outer shell, you can get a great balance of ventilation and insulation as you ride.
The effect is incredibly comfortable. The insulating layer fits tightly around your body and moves independently of an outer shell that keeps out wind and light rain. Its high, fleece collar adds to comfort and warmth when zipped right up.
At the rear there are three deep and secure pockets and there’s a small zipped pocket to the side for keys and valuables. Reflective piping gives you added visibility at night while double cuffs add comfort and the silicone waistband stops the jersey from riding up.
Colour options for the men’s version include Brilliant Orange, Light Black, Deep Bordeaux and this fruity Mango Mojito that I was testing out. It’s a really nice shade of what we used to call ‘yellow’, great for visibility but as I was to discover with late night roadside mechanicals, it does show up oil stains that I am still struggling to remove.
Fabric close up
If you like reassuringly complex marketing guff, then Polartec aims to please. It describes the AirCore fabric as a ‘highly engineered nano-fibre membrane’ that ‘enables a controlled airflow to keep you dry by escaping moisture and vapour at an industry leading MVTR of 25,000g/m2/24 hours, along with the combination of air permeability ranging from 1CFM…’
If you’re a fan of plain English – this is a brilliantly breathable material. It’s windproof, water resistant and it will stretch and move with your body to keep you comfortable even when you are slogging up one impossibly steep incline after another.
The outer shell works in conjunction with the inner panels of Alpha fabric that add insulation to your core and along the front-facing part of your arms. It’s a really effective combination that deals well with sweat to keep you dry.
Polartech says that its Alpha material is tough, light and that its ‘lofted fibres, mesh core and hydrophobic qualities’ are what makes it so breathable and fast drying.
And of course… it was designed for US Special Forces. So if you feel like invading somewhere far flung, this is very much the fabric of choice for today’s cycling soldier of fortune.
First night foray
I had to wait for the temperature to drop during an unseasonably warm autumn, before testing this jacket. The mercury hit a suitable 6°C on the very night I was leading an evening club ride to the coast. I half expected to overheat as I pedalled out of the city but as we hit a pocket of cold air on our first descent, I started to appreciate just what this jacket has to offer.
It kept my core beautifully warm as we rode across a misty section of moorland, with headlights bouncing off the water droplets hanging in the air. And as our first serious incline came into view, I unzipped the outer to get some cooling air inside and I hit the top of a steep climb feeling surprisingly fresh and dry.
As the temperature dropped on our final few kilometres, the Alpha 150 kept me perfectly warm. When we made it to the pub, I took it off to feel for patches where sweat had gathered. There was very little damp to speak of, even after a few hours of hard cycling. After a pint in front of a roaring fire, it was bone dry and ready for the ride home.
The Puncture Fairy
A few weeks later, approaching Salisbury at 2am on a 300km ride, I felt the air go out of my back tyre. There’s nothing worse than a puncture on a night ride. I really feel the cold when I’m sleep deprived and exhausted. So I zipped up the jacket, pulled a snood over my nose and got to work.
To be honest, five minutes of pumping the tyre back up is probably what kept me from starting to shiver uncontrollably, but the jacket definitely played its part.
That ride had started with drizzle and patches of sustained rain but the Alpha 150’s outer shell dealt easily with all of that. As we rode over Salisbury Plain, I kept hitting sections of really cold air and was delighted to be wrapped tightly inside this jacket, with a new Kostüme base layer underneath for good measure.
And as we rode through the New Forest and watched the sun rise over the sea at Bournemouth, I could not have been happier to be safely ensconced in a genuinely superb piece of kit.
And then the sun came up. The sky cleared. And the hills started to get steeper and more challenging. By the time we got to Milton Abbas, the temperature was around 9°C and approaching the top of the Alpha 150’s suggested range (-2°C to 10°C).
I was riding my fixed Van Nicholas and gunning to get to the cafe stop. When I finally placed my flat white on the table, and took off the Alpha 150, a gasp went up. A cloud of moisture lifted off my body as though someone had attached a smoke machine to my sternum. It lasted a good five minutes and was the source of delirious hilarity for a group of sleep-deprived audaxers.
I had come prepared with a cooler set of kit for the final 100km in daylight. The built in insulation is great when it’s cold, but when the temperature rises, it would be nice to be able to shed one of these two layers independently.
Rolling the jacket up, I realised it was going to take up a big chunk of my saddle bag. The Alpha 150 is really designed for a consistently cold winter ride that stays under 8° most of the day. This isn’t a piece of kit I’m likely to use on multi-day trips when temperatures look like they might be much higher than that for a sustained period.
And for me that limits how and when I might use this piece of kit. I love being out in winter but just how much use would I get from this top?
The ultimate winter jacket?
Is this ‘the ultimate winter jacket’? It is certainly one of the most comfortable winter tops I’ve worn. It has an almost magical ability to keep you warm and dry and it deals easily with light rain. But that price tag is eye-wateringly expensive and I would struggle to justify the investment.
Castelli’s International Brand Manager, Steve Smith, reckons it does have mass appeal, based on the 12-year evolution of this jacket. ‘For years, the Alpha has been one of our core winter products,’ he says, ‘and both amateur and pro riders tell us it their favourite jacket in cold conditions. With the Alpha 150, we are setting that benchmark even higher and delivering the best winter jacket we have ever made.’
I wouldn’t disagree with that. But I reckon digging around in your existing kit and using a strategic layering approach is going to meet the needs of most of us. The ability to add and shed layers that can be easily stashed in a saddle bag or back pocket is likely to be a far more practical approach for the majority of us.
Value
If you ride consistently through winter I have no doubt you are going to appreciate the outstanding combination of warmth and moisture control that this jacket provides. If this is within your budget and you plan on being out every week right through the coldest of months then you won’t regret buying it.
If you still want the Castelli logo and would rather take a layering approach then its Perfetto RoS costs £245. Liam gave it 9/10 when he reviewed it, praising its warmth, breathability and great fit.
George gave the MAAP Training Winter Jacket another nine-star rating. Its RRP is £270 but it’s less than half that at present, which deals with George’s main criticism – the price.
Costing a lot less but still very highly rated and the Altura All Roads Fleece costs just £90 and could be an effective part of a very good layering system.
Galibier’s Liberté Insulated Packable Jacket costs just £82 and is just the kind of top you can stash easily and pull on when temperatures drop.
The Galibier GrandTour Jacket delivers great warmth and comfort.
Pair either of these two with a good gilet and base layer and you have a solid winter combination.
For other options, check out our best winter cycling jackets buyer’s guide.
Verdict
The Alpha 150 is certainly an excellent winter jacket that is packed with new fabric technology. If you are a Castelli fan – and like to sport that white scorpion logo – then this is a great way to mark the 150th anniversary of a distinguished cycling brand.
It will deliver great performance on the bike for those months when the temperature drops. Despite its technical brilliance, its bulk and cost limit the mark I can give this.
That said, I’d love to have this jacket to hand for a Festive 500 or any of the day-long audax rides that I have planned through January and February. If you have deep pockets and you plan to be out all winter, then I can assure you that you won’t regret buying this one.
Verdict
Technically excellent winter jacket that will deliver if you ride consistently through winter – but mighty expensive
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road.cc test report
Make and model: Castelli Alpha 150
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?
This jacket is made for riding in cold and dry winter days.
Castelli says: “New for 2025, the Alpha 150 Jacket now uses Castelli’s exclusive Polartec® AirCore™ fabric for unmatched breathability in a windproof and rainproof fabric. On the inside, Polartec’s Alpha insulation provides warmth while enhancing moisture management. The stretchy close-to-body fit means you don’t feel like you have a full winter jacket on. This jacket is ideal for cold, dry days yet can stand up to everything except all-day driving rain.”
Tell us some more about the technical aspects of the jacket?
Outer layer made from 150 g Polartec® AirCore™
Polartec® Alpha™ inner liner for insulation: light weight with excellent moisture management
Top- and bottom-opening YKK® Vislon® zipper for easy sliding, covered for additional wind and rain protection
Zippered key/money pocket on front side
3 rear pockets
Reflective piping at bottom of pocket
This is a beautifully designed and thought out piece of clothing – construction is excellent.
It does exactly what it sets out to do – which is to deliver a brilliantly warm and breathable top for the coldest winter months. It will cope with a certain amount of rain and deal with everything up to a real downpour.
The jacket looks robust – stitching is excellent no signs of any issues during the test period
The jacket has performed well in light rain and delivers exactly as Castelli suggest. You will need to throw a rain coat on if you are riding in sustained heavy rain but it will copy very well with longer periods of drizzle and shorter showers.
Get this in the sweet spot of its temperature range and it performs brilliantly in terms of breathability. I found issues when I had a reflective gilet over the top for a couple of hours of night riding and when I was riding hard at the top end of its suggested range.
It delivers a great fit and this is in part because of the two layers on offer, with the inner insulation relatively snug but able to move independently of the outer shell. This delivers a sleek jacket with great comfort.
I hover somewhere between a large and X-large depending on the manufacturer. This was a large and delivered well in terms of sizing.
The jacket itself isn’t heavy but I am going to pick up issues with bulk here. If the temperature rises, you might need to stash this jacket – as I did – and that does require you carrying a little extra weight. If you are going to be using this exclusively for rides that stay under 8°C or so then it is less likely to be a problem.
Really very good comfort levels thanks to the jacket’s ability to deal with sweat and moisture.
Money is likely to be the deciding factor with this jacket. There are plenty of alternatives out there that offer better value for money but that don’t deliver the specific functionality that comes with this jacket. If you are likely to be using it just a few times over winter then it won’t represent good value. But if you are planning on using it to keep you riding consistently through the coldest of winter months then you could easily make a case for this as a solid investment.
How easy is the jacket to care for? How did it respond to being washed?
It’s fine to wash – although you need to pay close attention to care label – but I am still struggling to get oil stains out of the Mango Mojito (ie yellow) of the outer shell fabric.
Tell us how the jacket performed overall when used for its designed purpose
When riding at night in the sweet spot that this jacket is designed to operate it, it was a really excellent piece of kit and a delight to test.
Tell us what you particularly liked about the jacket
Its ability to deal with sweat and moisture means that I didn’t find myself shivering when I stopped for a midnight control or to deal with nighttime mechanical issues.
Tell us what you particularly disliked about the jacket
I wouldn’t use this jacket on multi-day trips because I found it too bulky to pack away when I did need to take it off. For rides where the temperature is likely to get warmer for a significant period, I’d be inclined to use a smarter layering system. I sense most people riding this will be doing shorter rides that they know are going to be at consistently lower temperatures.
How does the price compare to that of similar products in the market including ones recently tested on road.cc?
This is definitely more expensive than other pieces of kit out there but it packs in more fibre technology and with two layers on offer and the additional warmth, breathability and rain proof qualities that come with it, this is worth comparing to the cost of 2-3 items of clothing.
Did you enjoy using the jacket? Yes – absolutely loved using it in lower temperatures and on chilly night rides.
Would you consider buying the jacket? No – too pricey and it doesn’t match the needs of most of my winter riding.
Would you recommend the jacket to a friend? Yes – if they’ve the budget and it meets their needs.
Use this box to explain your overall score
Is this the Ultimate Winter Jacket? That really depends on who you are and what you want it for. As a piece of kit that shows what can be done with interesting new materials it is genuinely exciting. I have found it brilliant to use when the weather is really cold and exceptionally comfortable. It terms of its technical performance this scores a 9 at the very least. The price tag and its bulk limit the mark I am able to give it.
About the tester
Age: 0 Height: 180cm Weight: 83k
I usually ride: Specialised Langster (fixed commuter) My best bike is: Condor Fratello (new – Audax rides)
I’ve been riding for: Over 20 years I ride: Most days I would class myself as: Experienced
I regularly do the following types of riding: commuting, touring, club rides, general fitness riding, fixed/singlespeed, Audax
5 thoughts on “Castelli Alpha 150”
While this Castelli jacket
While this Castelli jacket and its Polartec makeup look great, I’m struggling to see how they match Endura’s excellent Pro-SL PrimaLoft® jacket. The latter is a little less expensive and a lot more versatile.
https://www.endurasport.com/men-s-pro-sl-3-season-primaloft-jacket-pomegranate/14876383.html
I count four zips on the
I count four zips on the endura to vent. So a sweat box
Not in my experience—the Pro
Not in my experience—the Pro SL jacket doesn’t sweat. I wish more brands offered similarly versatile ventilation.
https://road.cc/content/review/endura-pro-sl-3-season-jacket-289913
I count four zips on the
I count four zips on the endurance to vent. So a sweat box
Sweat boxes are receiving an
Sweat boxes are receiving an unfairly bad press! Several years ago I bought 3 black jackets from Aldi at £3 each. They’re very useful, a good fit andand at this rate I’ll be dead before they wear out. However, they do collect wetness at the bottom of the arms- a gravity effect? However, I was comfortable yesterday for 4 hours at 6-3°C and my back was fine. So were my feet, with my Aldi waterproof socks inside ordinary summer shoes. The only problem arises if you stop at someone’s house for a visit and the clamminess catches up with you. Then starting up again in the dark for the last couple of miles is a trial!