Castelli Alpha RoS 2 Light jacket review

At its launch, the Castelli Alpha Ros 2 Light winter cycling jacket had a big job ahead of it, if it were to earn its place in Castelli's revered lineup of winter cycling clothing. Such is the brand's popularity, its iconic scorpion logo is a sight you'll see at almost every winter club ride around the world. 

Ever since redefining winter clothing with the Gabba, Castelli has been known for making some of the best winter cycling jackets. We've already given a strong rating to the Alpha RoS 2 Light's bigger brother in our Castelli Alpha RoS 2 jacket review, so how does the pared-down Light version compare? 

Well for starters, it's probably unfair to call it pared-down. It's not simply a shoestring model of a better jacket made cheaper with worse materials and less tech, it leads a category of its own, integrating different technologies to cater to a different market. 

For all of its kit, Castelli provides a temperature range in which each item is supposed to be suitable. For the Alpha RoS 2 Light jacket, that range is 7C/45F to 15C/59F, putting it in an altogether different ballpark to the -5C/23F to 10C/50F quoted for its heavier brother. 

Design and aesthetics

Being an Alpha jacket means the Alpha RoS 2 Light gets two-layer construction, which, for those unfamiliar, basically means there's a warming second layer stitched onto the inside, providing double protection upfront for better temperature regulation and protection from the elements. At the front, it's not dissimilar to wearing a jersey beneath your winter jacket, but the single-layer back panel means heat is managed correctly, and you don't need to contend with the bunching effect of two (or three if using a base layer) long sleeves on each arm. 

This, in turn, means there are two zippers to contend with, which allows you to retain core temperature whilst opening up the windproof layer to expel excess heat on climbs.

On the RoS 2 Light, the inner layer is made using ProSecco Strada material, which is the same material used for some of Castelli's summer jerseys. The outer layer features GoreTex's incredible Infinium Windstopper 150 material placed strategically throughout, with the slightly thinner Nano Flex Xtra Dry on the rear. 

The cut of the jacket is undeniably geared towards road cyclists, with a narrow cut and aerodynamic shape. However, like the heavier weight jacket, the tight-fitting waist is let down by a chest and shoulder section that's a little loose when compared to the Perfetto or the Gabba. 

Specifications

The Alpha RoS 2 Light is equipped with four pockets. Three across the back in the usual fashion, and a waterproof zippered security pocket across the left side. The three across the back feature laser-cut drainage holes, which are surrounded by small reflective trim. 

Across the hem of the lower back, a solid silicone gripper keeps everything in place, aided by extra silicone in the form of a large Castelli wordmark printed on the inside. 

Taped seams are used across the shoulders to help keep out the wind and rain, and they are given a nice contrasting colour to aid with design. 

The zipper upfront is basic in function. There's no two-way action or cam-locking zipper, but in its simplicity lies a few positives. The zipper itself is large enough that you can easily fumble it into place while riding along wearing fat gloves, and the zipping itself is light-action enough that it's easy to slide up and down without a fight. 

However, my biggest gripe with the Alpha RoS 2 Light comes with the small neck guard that has been added at the inside top. Every time you zip up whilst riding, the zipper catches against this neck guard and stops, meaning if you want to zip right the way to the top, it's a two-handed job. 

The wrists forego the dual-layer construction in favour of a simple single layer. This means it might not have quite such a tight seal with gloves, but the sleeves are long enough that it plays nicely with most gloves. 

Performance

With the two-layer construction, the theory is that the inner layer works to wick away sweat and moisture, while the outer layer keeps the cold weather on the outside. In reality, it really works. And it's better than just wearing an extra jersey in many regards. However, the quoted temperature range is slightly high for me. 

Despite the quoted temperature topping out at 15C/59F, at around 12C/53F and up, I found that even while wearing a summer base layer beneath, I'd need to open both layers while climbing to expel heat. At the other end of the range, Castelli claims it bottoms out at 7C/45F, but I've comfortably been down to freezing with a couple of different merino base layers. 

Verdict

At £230.00 ($279.99 / €239.95 / AU$449.00), the Castelli Alpha RoS 2 Light is going to need to do one of two things: either serve multiple purposes adequately or serve a single purpose brilliantly. After four months of British winter testing, I am convinced that it's capable of both. 

If you're the sort of rider that will continue riding as the temperatures descend past frozen and beyond, or you're after a single jacket for winter riding and want warmth no matter the conditions, the heavier sibling is for you. 

However, for most riders, when the risk of ice arrives, riding outdoors ceases, so the best winter cycling jacket is one that performs dutifully in the degrees hovering above. The Alpha RoS 2 Light does exactly that, while being entirely suitable down to freezing and on warmer spring afternoons. It's versatile enough to be ridden through a temperature range that covers three quarters of the year - and that's why I'd buy the Castelli Alpha RoS 2 Light jacket. 

Tech Specs: Castelli Alpha RoS 2 Light jacket

• Price: £230.00 / $279.99 / AU$449.00
• Material: GoreTex Infinium Windstopper 150, Nano Flex Xtra Dry, ProSecco Strada