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Introducing the Castelli Alpha RoS 2: the Ultimate Winter Jacket

By Stan Portus –  10 September 2020

Castelli has brought some fresh updates to its ultimate winter jacket, the Alpha RoS 2. Every detail is designed to help you ride longer and in complete comfort come rain, wind, snow, or whatever foul weather mother nature throws your way.


When designing the original Alpha RoS jacket, Castelli started with a list of things that it didn’t like about winter jacket design and set to change them.

In the process Castelli did to winter jackets what it did to foul weather racing jerseys with the Gabba, creating a jacket that did away with the need for cumbersome layering and ensured excellent foul weather protection was matched by superb breathability.

This meant that even in the depths of winter riders could benefit from greater performance and comfort for the months of the year that are often defined by compromise.

In short, Castelli completely changed the game.

Always seeking an advantage, Castelli has fined tuned the Alpha RoS for Autumn Winter 2020. The Alpha Ro 2 is the result, and it offers even greater warmth, breathability, and comfort. Ideal for the winter months ahead.  

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Alpha Construction

Model unzipping the Castelli Alpha RoS 2 to reveal the internal vest

The Alpha RoS 2 uses Castelli Alpha construction. This is a double layer that consists of an exterior jacket and internal vest that hugs close to your body, and offers insulation down to -5˚C. 

You can allow airflow to enter the jacket to evacuate moisture, without cold air coming into direct contact with your skin. On long climbs and punchy parcours the outer layer can be completely opened for maximum ventilation.

For 2020, Castelli has updated the insulating layer fabric. The 3D insulating fabric with a waffle-like appearance provides better warmth, moisture management, and fit.  

Wind and Rain Protection

Photograph of the taped shoulders on the Castelli Alpha RoS 2 Jacket

The Alpha RoS 2 is part of Castelli’s Rain or Shine family. The guiding principle behind Rain or Shine (RoS) is dress for the temperature and don’t worry about the weather.

With the Alpha, this ethos is made possible by the use of GORE-TEX INFINIUM™ WINDSTOPPER® fabric. This blocks out all the wind and keeps you dry through mist, wet roads, and incessant rain while remaining breathable.

Castelli calls the Alpha RoS “essentially waterproof”, striking a balance between rain protection, breathability and comfort. It doesn’t mean no water will get in, but you will find that on longish rides in real rain you’ll stay completely dry.

Castelli has also strategically placed seams shielding them from direct exposure to the elements. Critical seams on the shoulders are taped to prevent moisture entering the jacket.  

New Wrist Closure

Close up photograph of the wrist on the Castelli Alpha RoS 2 jacket showing the GORE-TEX INFINIUM graphic
Close up photo showing the double layer design of the Castelli Alpha RoS 2 new wrist design

A new wrist closure for the Alpha RoS 2 eliminates any exposed skin where winter gloves meet jacket sleeves.

A double-layer design means an inner layer seals tight to the wrist and an outer layer goes over your glove, so any rain rolls down the outside of your glove and doesn’t end up getting inside.  

Back Ventilation and Improved Fit

Photograph showing the back of the Castelli Alpha RoS 2 Winter Jacket

Two vents on the back of the Alpha RoS 2 let moisture and heat escape from the jacket. Due to the overlapping layers of the vents you won’t feel any cold, but you stay significantly drier on the inside.

While adjusting the back of the jacket for ventilation Castelli also created a narrower back panel on the top of the back and introduced more width to the jacket’s chest panel, improving fit in the riding position. The new cut accommodates a wide range of body types and positions on the bike. 

Easy Reach Pocket

Close up photograph showing model opening the side pocket on the Castelli Alpha RoS 2 jacket

Reaching round the back of a jacket to rear pockets can be cumbersome with thick winter gloves. The Alpha RoS 2 has a pocket on the left side panel of the jacket so any essentials are within easy reach. It closes with a zipper too, so you can safely stow valuables such as a phone, keys, or bank card. 

Shop Castelli RoS

Key Features

• Rain or Shine engineering makes the Alphas RoS 2 Castelli’s best jacket for cold dry conditions while providing significant rain protection

• GORE-TEX INFINIUM™ WINDSTOPPER® 150 fabric. Highly breathable wind protection and effective rain protection

• Minimal seaming with seam sealed shoulders reduces chances for water to enter through stitching

• Double-layer Alpha construction separates insulating layer from the wind/water external barrier to let you better regulate ventilation

• Water-resistant YKK® Vislon® zipper slides easily

• Raw-edge waist with silicone gripper lies flat and seals out wind

• Double-layer cuff integrates with glove to prevent cold wind and water entering

• Stretch fabrics with advance patterning for excellent close to body fit

• Back ventilation

• 3 rear pockets with reflective laser-cut drain holes

• Zippered secure side pocket for valuables

• -5˚ – 10˚C / 23˚ – 50˚F

• Weight: 525g (Large, Men’s) / 454g (Small, Women’s)

Alpha RoS 2 Light: For Milder Conditions

Photograph showing the back of the Castelli Alpha RoS 2 Light Jacket

Alpha RoS technology and construction, but for milder conditions.

The Alpha RoS 2 Light Jacket shares much in common with its deep winter sibling. It has the same GORE-TEX fabric in the front and sleeves to protect from wind chill, but has a lighter Nano Flex Xtra Dry back panel to introduce greater breathability making it suitable for riding in temperatures between 7 – 15˚C.

The perfect jacket for the transitional seasons, and higher intensity workouts. 

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