Castelli Alpha Ros Jacket review

Castelli claims to have reinvented the archetypal cycling jacket. Bold claims indeed, but with wind and water proofing, insulation and breathability apparently accounted for in a sub 400gram jacket - could the Castelli Alpha Ros be the ultimate winter jacket?

Castelli Alpha Ros Jacket
Cycling Weekly Verdict

Water resistant, windproof and thermal, the flyweight Castelli Alpha Ros Jacket makes bold claims and delivers every single promise. It's one of the most impressive pieces of kit I've seen in a long time, just be prepared to pay for it.

Reasons to buy
  • +


  • +

    Water resistant

  • +

    Female and male options

  • +


  • +


  • +


  • +

    Low Profile

  • +

    Race cut fit

  • +

    Cuff design

  • +

    High double collar

  • +

    Taped shoulder seams.

  • +

    Pocket design

Reasons to avoid
  • -

    Low on reflective details

  • -

    Small Zip secure pocket

You can trust Cycling Weekly. Our team of experts put in hard miles testing cycling tech and will always share honest, unbiased advice to help you choose. Find out more about how we test.

When in comes to cycling kit innovation, Castelli doesn't muck about. It's been at the forefront of research and development since the year dot, with products such as the Sanremo 2 Thermosuit, Body Paint 3.0 Speedsuit, and of course not forgetting the game changing Gabba.

It's safe to say when it comes to clothing technology, Castelli knows its onions, so while bold 'reinvention' claims by many brands might give us an itchy chin, when the Castelli Alpha Ros landed with a huge winter jacket wish list apparently ticked, we had to sit up and take notice.

Castelli Alpha Ros jacket construction

As expected, the Castelli Alpha Ros Jacket has had all the technical bells and whistles thrown at it. The fabrics and methods used in construction reads like a phd thesis.

If it looks familiar, then it's probably because many of the key design attributes are taken forward from the jacket's predecessor, the Castelli Alpha, with the obvious one being the two piece construction creating inner and outer layers.

Castelli Alpha Ros Jacket

Available in both male and female options, the Castelli Alpha Ros Jacket says it has winter covered.

Castelli say that by separating the inner thermal layer from the outer wind and waterproof layer you get better ventilation and moisture management, and arguably better insulation by the creation of a warm air pocket.

In laymen terms, at the back of the integrated waistcoat a thermal mesh fabric is used whilst a Polyester Elastane mix waffle-like material sits at the front. This same fabric is also double layered in the front of the arms.

>>> Winter bikes: buyers guide to 2018 models 

The outer uses industry gold standard GORE Windstopper. We've waxed lyrical over this fabric over the years and are still yet to find a better windproof, water repellent and breathable fabric.

The devil, however, is in the detail, and it's normally an area where Castelli excels.

The cuffs have been made from a high elastic mix Polyester, and are effectively fleece backed elastic, which allow them to provide warmth while preventing any draft gaps. As well as being seamless and raw cut , they're also longer at the front of the arm (back of the hand) - a great combination when partnering with gloves.

The Castelli Alpha Ros Jacket also gets an extra collar, which is doubled up, with a fleecy inner ensuring a very snug fit around the neckline.

At the back there are three good sized rear pockets, with an additional smaller zip secure one located on the right hand side. The waistline, from pockets down and flowing round to the front, is a high elastane mix raw cut finished Polyester, again keeping the bulk down of the jacket as well as laying flat to the waist.

Finally, one of the most exciting things about the Castelli Alpha Ros Jacket is that it's available in both male and female options. Awesome to know that exactly the same level of weather protection is offered to both sexes.

The Ride

Having reviewed several winter jackets back to back, the first thing that is noticeable about the Castelli Alpha Ros Jacket is how low profile it is. Weight wise, the 399g Castelli claim is slightly indulged, but 412g for a women's size small isn't too shabby, and for the level of protection it offers, it certainly still qualifies for lightweight.

Pull the women's version of the Castelli Alpha Ros Jacket on and it's clear you are in high end territory. Just everything about it is on point: the snug race cut fit, the double layer system, the high collar, raw cut edges on the cuffs and waistline, it's all delivered perfectly.

The only design grumble is the minimal reflective details. The men's equivalent version has a fluro orange option and there is a rather bold turquoise or red offering for women, but as soon as the light fades, these aren't great visibility wise, and I'd personally love to see a few more reflective strips up the back.

Testing this as the north was gripped by a reasonable dusting of snow and plenty of ice, it meant my only option was to hit the gravel roads across the moors. I was apprehensive - it's such a flyweight in stature, that I was desperate to reach for a more padded number. But my word Castelli has delivered. What a jacket. It was around 2°C on the thermometer, but with wind chill much more like -5°C , the Alpha Ros didn't skip a beat.

The double front and arms worked perfectly, totally cutting out the wind chill and acting as great thermal agents. It was so blowy on the tops that at times I did feel the chill on the inner arm, where it's not double layered, but if you press on and work a bit harder, your natural body heat will counter this, plus this section also acts as an exhaust - giving the jacket great breathability.

Every element of this jacket delivers, from snug collars to perfect pairing with winter gloves.

The fit of the Castelli Alpha Ros Jacket is race cut. Feeling like a warm jersey, it's actually hard to believe that it can offer such great thermal insulation. Under constant attack from snow and icy slush puddles I was expecting the water resistance to be breached after an hour or so, but wet slush just beaded off without any jacket penetration.

One of the biggest telling signs of the jacket's performance was at the end of the ride. When I'm normally gagging to get out of wet kit and remove sweaty soggy base layers, I was so dry and warm still that once I'd removed the icy muddy slush sprayed jacket, I was able to just shove a jumper on over the base layer and drive home in it.

The pockets are big enough for tubes, tools, and snacks. The only disappointment is that the perfectly positioned side pocket wasn't large enough to fit my iPhone 6 with a case. It might fit one without a case at a push, and I suspect the larger sizes get scaled up pockets too, so shouldn't be an issue, but it would be great to see Castelli remedy this on the next iteration.


There's no denying that the Castelli Alpha Ros Jacket is high end, in fact at £260 for the men's version (£250 for the women's we had on test), it's probably one of the most expensive on the market. But my goodness, what an exquisite piece of kit it is. Just putting it on will instantly make you feel like a pro rider. There are cheaper winter jackets out there, and some will keep you just as warm, but not for the fit and feel. If you're looking to train hard with zero compromises in performance then this is for you.

Thank you for reading 20 articles this month* Join now for unlimited access

Enjoy your first month for just £1 / $1 / €1

*Read 5 free articles per month without a subscription

Join now for unlimited access

Try first month for just £1 / $1 / €1