Zero Compromises.

The Castelli Women's Alpha ROS jacket is its most technical one to date and fills in right between a light jacket and a warm jacket. The ROS (Rain or Shine) excels in both cold and dry or wet and cool conditions with Windstopper fabric material on the front and sleeves and a Nano Flex Xtra Dry back for extra breathability.

This jacket's strongest suits are keeping you warm yet dry and the regulating temps during chilly departures and high-intensity efforts. The Alpha double-layer construction front helps you manage ventilation and lets this piece go from mild conditions down to cooler temperatures. While it's not guaranteed to keep you as dry as an all-out rain jacket, the Alpha ROS does keep you warm and dry in the widest range of conditions.

Below the Windstopper front, a ProSecco Strada liner with its own zipper works to remove sweat and prevents you from getting wet and chilled from the inside. On hill repeats or intervals, unzipping the outer layer lets you cool your engine without forgoing all protection.

Advanced patterning of the material allows for an excellent close-to-body fit, and the extra stretch at the waist keeps the fit sleek while a raw-edge waist lies flat and moves with you. A Castelli silicone text gripper at the waist keeps the jacket from riding up, and three rear pockets, with reflective laser-cut drain holes plus a front zippered pocket, carry everything you will need for a big day—and possibly damp—on the bike.

Castelli calls this a jacket, but we think it's more than that. Perfect for intense rides in wet or variable weather conditions on cool days and windy rides, the Alpha ROS jacket offers protection that strikes just the right balance to keep you dry and comfy all day.

  • Versatile jacket for cool rides in wet or dry conditions
  • Windstopper membrane leads into rain and wind
  • Inner layer zips separately to tailor protection
  • Breathable back panels boost moisture evacuation
  • Slim fit perfect for group rides and early spring races
  • Reflective accents on pockets improve your visibility
  • Three rear pockets with drain holes stash ride snacks
  • Zippered front pocket adds secure storage
  • Reviews
  • Q & A

Runs extra small

  • Familiarity: I returned this product before using it

Really cute and looks well made. Couldn’t even get it on. Im a size 6 in jeans and a small or medium in tee shirts. Im 5’6” and weigh 130 lbs. the medium was way too small. Im returning it for an XL and hope it fits 😳

Yeah, Castelli runs very small. In fact, most (all?) Italian cycling brands seem to run small.