Castelli Alpha Ros Jacket Review

By Guillaume Judas – Photos: 3bikes.fr

The Alpha RoS is a very technical jacket, designed for temperatures below 5°C, very well cut (meaning quite fit and not flapping in the wind), and likely to protect you from water splashes or even light rain. It is not a completely waterproof jacket. But then, do truly waterproof jackets even exist in heavy downpours? Because while some materials prevent water from passing through the garment, you always end up getting wet, either from contact with other clothing (tights in particular) or because water penetrates through the neck.

This is not what the Alpha RoS promises; it focuses primarily on its versatility. It is also not the warmest in the range, but it is the most athletic among the Italian brand’s jackets designed to face the rigors of winter. In short, as soon as you ride actively in temperatures from -5 to +5°C, it becomes essential.

Attention to detail

As often with Castelli, it’s the details that make the difference. The Alpha RoS is constructed in two parts, with a technical outer layer of Gore Windstopper 150 (wind protection combined with high breathability and effective rain protection) and a fleece-lined inner layer around the body, much like an inner vest.

The jacket is therefore put on by closing two zippers one over the other, but this offers a certain advantage under certain conditions, as we will see later. To minimize moisture entry, there are sealed seams on the shoulders, a waterproof outer zipper covered two-thirds by a Windstopper flap, a flat waist hem with a silicone band and Castelli logo for a perfect fit of the jacket during movements, and long cuffs also with a flat hem for a perfect junction with gloves.

The outer layer is also lined on the front of the arms. Body moisture wicking is ensured by a separation of the Windstopper layer at the shoulders for better ventilation.

The collar rises high, its interior is fleece-lined for comfort, and an additional arc-shaped layer follows the movements of the neck to limit cold air entry.

Moreover, the Alpha RoS jacket is particularly remarkable, like most of Castelli’s fit garments, for its close-fitting cut made possible by stretchy fabrics and a design adapted to the cycling position. No zippered back pockets, but three classic pockets, nevertheless enhanced with three small holes around the small reflective strips, to drain water if necessary.

For practicality, it’s better to have easy access to pockets if you’re wearing gloves. There is, however, a small zippered pocket on the front of the jacket, bottom left, possibly for slipping in a key, a bank card, or some change – in short, anything you’d rather not lose on the road.

High-level insulation

These two superimposed layers already allow for some heat regulation, thus avoiding the need to layer up under the jacket. In practice, a single long-sleeved technical base layer is usually sufficient under the jacket. And for those who plan to use it in extreme conditions, one could imagine adding another base layer, short-sleeved for example. But given the snug fit, an additional long-sleeved jersey would not only be uncomfortable, giving the impression of being constricted under the jacket, but also unnecessary. By closing both zippers one over the other, the Alpha RoS is really warm, allowing you to ride comfortably around 0°C as long as you are minimally active. At higher temperatures, you might even feel slightly damp inside, but curiously, if you stop at the side of the road, you don’t shiver from what could be called cold sweat. The jacket allows you to quickly regain balance, proof of its good thermal exchange management. But it is, of course, by playing with the opening of one of the two zippers that you manage best during effort. Those who get too hot while riding can always partially open the inner lining. As for the outer zipper, it is ideal to manipulate for ventilation or not, for example, during a long climb.

Rain tested

As mentioned above, the Alpha RoS is not 100% waterproof, but it resists frequent light rain or water splashes very well. After a two-hour ride in drizzle, nothing got through. And in case of heavy downpour, the protection is still above average. The outer layer remains windproof, and the close fit minimizes cold air infiltration through the neck or sleeves. In short, you eventually get wet, but you shiver much later than your friends.

Finally, we appreciate this particularly visible orange color in low light conditions. This is also a small criticism that can be made of the Alpha RoS (in another color, as it is also available in red, black, or grey/blue), which is the lack of reflective strips, although here it is not a real problem.

A price to match

Two downsides to this almost idyllic picture: a slightly high weight at 465 g in size S, but this is the consequence of a two-part construction and remarkable technicality, and finally the price. At €299.95, the Alpha RoS is not cheap, though it remains on par with many competing jackets. Even if we prefer lighter jackets for more temperate conditions (a bit lighter and less warm), we are not far from thinking that the Alpha RoS stands out as the first jacket to acquire for those who are starting to equip themselves, in addition to summer outfits, of course.

However, we are approaching the end of the winter season, and as often with Castelli, stocks are not unlimited. So don’t hesitate to check the Alpha RoS off your wish list. It’s already a best seller.

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