Castelli Women’s Alpha RoS Light jacket

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. 

> Find your nearest dealer here

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.

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.

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 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 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.

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.

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.

The laser-cut holes are reflective, too.

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.

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.

Verdict

Top-end winter jacket with brilliant wind and rain protection