Castelli has worked through a few generations of what is now the Alpha RoS (Rain or Shine) 2 Jacket, which is intended to be their ultimate cycling jacket for temps from 25°-50°F, and more than capable of blocking wind and water. Castelli enjoys a close working relationship with GORE-TEX®, ensuring the expertly informed use of the best technical fabric systems made to achieve the desired garment. By employing the dual-layer Alpha jacket design, the team at Castelli can isolate the thermal layer from the protection and membrane layer, allowing for greater temperature and condition flexibility. The 3D grid-like fleece thermal fabric is ideal for the inner layer, which is attached to the outer, but not continually. For the outer layer, they used GORE-TEX INFINIUM™ WINDSTOPPER® 150 fabric, a true thermal 3-layer membrane system that completely blocks wind and maintains heat while allowing moisture to escape via billions of micro-pores and pass out the uni-directional outer. For high-level water resistance, durable water repellent (DWR) treatment is applied by GORE to outer layer. This penetrates a jacket’s outer fibers, lowering the surface tension so that water beads up and rolls off. Castelli opted to reduce and hide seaming, while sealing the crucial seams to offer even greater water protection. Read on for Castelli's detailed process or skip down to the Details for the essentials.

In creating the Alpha ROS 2, the design team faced several challenges. The first issue was to resolve related to moisture management. Even the best of the currently available fabrics provide a good level of breathability but can't keep up with the sweat generated during high-intensity riding. This where Alpha comes in. The double-layer construction allows you to open an outer wind-protection layer while keeping the insulation layer closed and thereby allowing airflow inside the jacket to evacuate moisture while avoiding direct contact with the skin. On a long climb the rider can completely open the outer layer to allow moisture to escape, and when facing the descent the rider can close the outer layer and be completely dry inside. It works so well that sometimes it feels like magic. New for the Alpha RoS 2 is a softer, warmer 3D insulation-layer fabric that provides better warmth, moisture management and fit.

Next the designers focused on the openings: neck, waist and, most of all, wrists. The soft and flexible neck comes up high and is shaped to move with you, whether you're standing or in a low, aero position. For the waist they've created a stretch layer with a silicone bead that lies flat and completely seals out wind without bunching or riding up. Added in this generation is a brand-new double-layer wrist opening with an inner layer to go under your glove that seals tight to your wrist, and an outer layer that goes over your glove so that any rain will roll down the outside of the glove and not end up inside. In addressing these areas, it is actuslly useful to point out that the designers added openings, though not front facing. As part of the moisture management system, two flaps allow the two layer to move air through and out when the front is open as described above, but become offer more passive when closed up. These follow the shape of the lower scapular on each side and have enough overlap to prevent intake from the rear.

Of course, the ultimate jacket will also hold up well in wet conditions, where the GORE-TEX INFINIUM™ WINDSTOPPER® 150 fabric was the key to performance, along with waterproof seam taping on critical seams around the shoulder. Other seams are hidden out of direct water flow, and the DWR water-repellent treatment on the fabric is sufficient to prevent most moisture from entering. Castelli considers it essentially waterproof, using their own subjective judgment to find a balance between water protection, breathability and comfort. It doesn't mean that no drop will ever come in, but one can do longish rides in real rain and stay completely dry.

It is the combination of all these features that make the Alpha ROS 2 Jacket a favorite of the Team Ineos riders, and the most versatile performance jacket for cold-weather training Castelli has ever created. If you see your requirements in the above story and want to train at a high-level with a jacket that not only matches yours, or actually raises it, you won't find another piece like it on the market.