Castelli Alpha RoS Jersey review

Italian apparel manufacturer Castelli continuously refines core pieces in its collection. The iconic Gabba is on its third version and the Alpha jersey’s latest update added three season functionality to my wardrobe that felt like it was sorely missing. New to the Alpha is increased protection against the elements which Castelli calls Rain or Shine. The Alpha RoS Jersey’s versatility extends beyond other pieces of cycling apparel I rely on when I ride.

Materials and construction

The Alpha RoS is a workhorse. Like its name suggests, it’s resistant to the elements with the front and sleeves of the jersey made from Windstopper 150. While not an overly thick material, it’s lightweight makes it less likely I would overheat in changing conditions and it’s very resistant to water penetration. Whether climbing on a cool spring day or descending in the cold, this piece kept my body temperature regulated.

The back is made from Nano Flex Xtra Dry which allows for better ventilation than the Neoprene Windstopper fabric but offers good rain deflection. The back is so water repellent that Castelli felt the need for drainage holes at the bottom of the three back pockets.

The real unique feature of the Alpha is the inner baselayer that is sewn into the jersey. The ProSecco Strada liner has its own zipper and on rides when you unzip the outer jersey you still have this protection on your chest. On warmer days it meant I entirely left my baselayer at home while in cooler temperatures I comfortably wore a long sleeve baselayer underneath the Alpha RoS jersey.

Other features of the Alpha RoS jersey I liked were the high collar which provides excellent protection against the cold and the raw-edge waistline which offered stretch but kept the jersey comfortably in place. A zipped pocket on the side of the jersey is perfect for storing snacks or wrappers you’ll discard after the ride.

All weather performance

The thin fabric allowed me to continue wearing the jersey into the low teens and if there were alpine climbs close to where I lived, I would have continued to rely on this piece even later into the season as conditions at altitude would have merited it.

As with all long sleeve jerseys, I was worried I would easily overheat in the Alpha RoS especially given its bolstered rain protection. While the Alpha RoS jersey can’t replace a Gortex rain jacket like a Castelli Idro when it’s pouring, it can keep you far more comfortable when riding in the rain or if you are exposed to road spray. Additionally, it will entirely protect you if you encounter a rain shower. The combination of cold and wet is never a good one for a cyclist. The Alpa RoS jersey is the answer. The seams on the shoulders are sealed with a reflective material that gives the jersey a unique aesthetic.

When the temperature shifted to become a little warmer on my rides, I was comfortable unzipping the jersey to allow increased ventilation. I could see this being particularly handy on a climb in the Alps when you heat up on a long climb but need good protection for the cold and long descent on the other side. The next time I travel to the mountains where the weather can be cold, wet and unpredictable regardless of the time of year, the Alpha RoS will be coming with me.

Conclusion

The Castelli Alpha RoS jersey is a lightweight long-sleeve piece that offers the protection of a heavier jacket. Combined with the inner baselayer and sturdy weather protection, it’s comfortable in a variety of conditions making it more versatile for riding in the autumn, winter or spring. At $385, this is a feature packed jersey you can lean heavily on to make riding in challenging conditions easier.