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Castelli Women’s Alpha RoS Light jacket



Top-end winter jacket with brilliant wind and rain protection

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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The Castelli Women's Alpha RoS Light is, I believe, one of the best winter jackets on the market. Unless you're riding in heavy rain for hours and hours, you won't need another rain jacket; rain or shine, this one keeps you warm and dry.

  • Pros: Windproof, mostly waterproof, breathable, versatile
  • Cons: Expensive

Ashley reviewed the men's version of the heavier-weight RoS (Rain or Shine) jacket and loved it too. This is the Light version, but it still lives up to its name. 

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I've always believed layering is the way to go – baselayer, jersey, then jacket for wind and rain protection – but like Ash, I'm thinking the Alpha RoS could change the way we dress for cycling because this jacket is essentially a jersey-like layer with wind and waterproofing features, along with some insulation.

Castelli Alpha Ros womens jacket - riding.jpg

A while back, before I tested this jacket, I set off in the early morning temperature of 6°C and finished the ride in 15°C, having to strip off layers and find somewhere to stow them. The Alpha RoS removes the need for so many layers, and makes riding in the winter more convenient.

> Buyer's Guide: 18 of the best winter cycling jackets

Castelli has designed this jacket with two layers. The outer layer has Gore Windstopper 150 fabric on the front and top of the sleeves, while the back and underneath of the sleeves are Nano Flex Xtra Dry, which provides some water protection and breathability, as well as being warm, fleecy and soft against the skin.

Castelli Alpha Ros womens jacket - shoulders.jpg

A second, inner layer provides insulation. With a separate zipper, it looks a bit like half a waistcoat sewn into the jacket, and you can unzip during the ride to regulate your body temperature, on climbs for example. As this jacket keeps you warm, dry, and protected from the wind, you really don't need any other outer layer.

Castelli Alpha Ros womens jacket - lining.jpg

Castelli recommends a comfort range of 8-15°C. Below this, at 6°C, I put on a light-long sleeve baselayer as the Gore Windstopper fabric isn't fleeced on the arms. At 8°C I wore a light vest baselayer, had everything zipped up, and was very comfortable. At 15°C, the top end of the temperature range, I unzipped the inner layer completely and the outer layer slightly.

Castelli Alpha Ros womens jacket - lining seam.jpg

Castelli has also thought about a lot of other features to keep you warm and protected. The collar is fleeced and sits really nicely on your neck so the wind doesn't get in. The cuffs are flat, keep the wind out, and allow you to pull your gloves on easily. The waist of the jacket sits flat and has a drop-down tail with gripper.

Castelli Alpha Ros womens jacket - gripper.jpg

The Alpha RoS has reduced seaming and sealed shoulder seams for extra rain protection. In addition, the combination of a waterproof front zipper, rain-resistant membrane and treatment on the fabrics mean it is essentially waterproof while not compromising on breathability. However, do remember that it isn't a full waterproof; some rain can get in. Prolonged riding in the rain will need a full waterproof.

Castelli Alpha Ros womens jacket - shoulder.jpg

The jacket has three classic pockets with laser-cut holes to drain rain water. The pockets are deep enough for all your cycle essentials, plus there's a fourth zipped pocket at the side for keys or money.

Castelli Alpha Ros womens jacket - pocket.jpg

The laser-cut holes are reflective, too.

Castelli Alpha Ros womens jacket - reflective 2.jpg

It's a very comfortable jacket to wear. I would normally wear a medium, and the Alpha RoS was a good fit; I wouldn't need to go a size up as can be the case with some Italian kit. (It's not me in the photos.) The jacket weighs 372g, which is comparable with other winter jackets I have tried, and it didn't feel bulky at all.

Castelli doesn't guarantee that 'no drop will ever enter the jacket', but in light rain and showers the water beads off all the different fabrics. The most waterproof fabric seems to be that on the top of the arms and front of the jacket. The Nano Flex Xtra Dry fabric on the back holds off a shower, but when I got caught in 30 minutes of heavy rain it felt a little damp.

Castelli Alpha Ros womens jacket - back.jpg

All in all, I felt dry in a shower, but some water got in during a full-on downpour, which is pretty good for a jacket that doesn't claim to be fully waterproof. It will do a great job at keeping most of the water out in anything but the most unpleasant of weather conditions.

> Buyer's Guide: 21 of the best waterproof cycling jackets

It's a very good jacket, but it isn't cheap. It does a better job in the wet than the dhb Aeron Full Protection Softshell, but the dhb is very good value at £110 rrp, saving you £100. If this is more your price range, the Lusso Ladies Aqua Repel v2, at £135, is also worth a look, with its water-repellent and windproof fabrics.

Overall, I really like the Alpha RoS Light. It's a jack-of-all-trades winter jacket, packed full of features to keep you warm and dry. Yes, it's a pretty eye-watering price tag, but its versatility really appeals: you can buy this jacket instead of an expensive waterproof and use it more often – in rain and shine.


Top-end winter jacket with brilliant wind and rain protection test report

Make and model: Castelli Women's Alpha RoS Light jacket

Size tested: Medium

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?

Castelli says: "The Castelli Alpha RoS Women's Light Jacket might be that elusive an adaptable piece that you will be wearing for 6 months of the year.

"Much more than the name suggests the wind and water-resistant construction allows you to stay dry in most conditions. While the Nano Flex Extra Dry on the back is used for its water resistance and breathability as much as its used for its close almost jersey like fit.

"The main body at the front contains a second layer with its own zipper allowing you to run with either a light windproof or highly breathable thermal layer exposed to the wind - or close both up for superior warmth and protection.

"The now standard 3 rear pockets allow easy access to on the bike requirements these feature drain holes finished in a reflective tape. Additionally, there is also a side pocket with zipper for keeping cash or keys in."

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

Castelli lists these features:

Gore® Windstopper® 150 front and sleeves

Nano Flex Xtra Dry back for the most significant non-membrane water protection available

Reduced seaming with selective seam sealing on the shoulders

Prosecco Strada inner liner with separate zipper

Waterproof YKK® Vislon zipper

Articulated collar for the best fit ever in any position

Cross wrap raw-edge cuffs perfect with or without gloves

Side zippered key pocket

3 open rear pockets with reflective laser cut drain holes

Raw-edge waist sits flat and moves with you

Advanced patterning makes for an excellent close fit on a wider range of body shapes

Castelli silicone grippers to prevent ride up.

Sizes - Women's XS-XL

Weight 340g (S)

Castelli Comfort range 8˚-15˚C

Rate the jacket for quality of construction:

The construction of the jacket is excellent.

Rate the jacket for performance:

In the conditions it is designed for it performs really well. It doesn't keep water out completely but Castelli doesn't claim that.

Rate the jacket for durability:

So far it's holding up well after many uses and washes.

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

Castelli says it keeps most water out – which I'd agree with, showers and light rain. In heavy downpours the water creeps in.

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

I had no issues with overheating and becoming too sweaty. I felt the jackets fabric did its job well.

Rate the jacket for fit:

Testing the medium, the fit for me was great: a jersey-like performance fit, without being really tight.

Rate the jacket for sizing:

For the medium jacket, it sized up well. I take a medium in most clothes, and many say Castelli kit comes up small but that's not the case for this jacket.

Rate the jacket for weight:

For a winter jacket I was happy with the weight, seeing as it is windproof and virtually waterproof. The liner inside adds to the weight.

Rate the jacket for comfort:

I found it really comfortable to ride in.

Rate the jacket for value:

It is expensive at £210, but you could wear it for six months of the year as it is a versatile and quality jacket.

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

I washed according to instructions – 30 degrees, no softener – and it has been fine. Dries fast too.

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

For cold, dry and showery weather it was a great jacket to wear.

Tell us what you particularly liked about the jacket

Its water-repellent fabric, meaning you don't have to carry a jacket if light rain or showers are forecast.

Tell us what you particularly disliked about the jacket

Can't fault the jacket; it is pricey, that's my only dislike.

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

It's £100 more than the dhb Aeron Full Protection Softshell (£110), but the Alpha RoS does a better job in the wet; it's also a fair bit more than the Lusso Ladies Aqua Repel v2 (£135) with its water-repellent and windproof fabrics.

Did you enjoy using the jacket? Yes

Would you consider buying the jacket? Yes – in the sales.

Would you recommend the jacket to a friend? Yes, if they ride in the winter in most weathers.

Use this box to explain your overall score

It's an exceptional jacket that you really could wear six months of the year with its wind and weatherproofing features, helping to justify the price.

Overall rating: 9/10

About the tester

Age: 36  Height: 168cm  Weight: 60kg

I usually ride: Genesis Croix de Fer Ti  My best bike is:

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

I regularly do the following types of riding: touring, club rides, sportives, general fitness riding, mountain biking

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Tjaardbreeuwer | 5 years ago

I think this is a great jacket. The super light Windstopper fabric is so thin that having the extra layer of fabric at the front is very useful, since that is where you will feel the cold the most. Then, if the wind dies down or you are climbing, being able to unzip the front winstopper while still having an extra layer is really nice.

That said, the Perfetto Light short sleeve uses the same fabrics, minus the sewn in front layer and the taped shoulder seams. I think it offers more versatility:

Combine it wind windproof arm warmers and a baselayer with warmer/tighter weave on the front and you have the same level of protection and insulation. Yet on warmer days, you can use plain, non windproof armwarmers for a bit less warmth, and if it warms up, you can completely remove the armwarmers.

In this way, the only benefit to the ROS light is the the comfort and ease of dressing from the “all in one” nature of the jacket, but the Perfetto Light is more versatile. Choose according to your priorities.

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