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Castelli Alpha ROS Jacket- Limited Edition
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Item # CST00JS

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Item # CST00JS


Embrace the unpredictable.

Your cycling wardrobe likely consists of wet-weather gear and dry-weather gear, with little overlap. Until recently, those really were the only options, with wet-weather gear that would leave you feeling bogged down and steamy when you get pedaling, and dry gear that just couldn't hold up to more than a couple of raindrops. Castelli created the Gabba and Perfetto to help cover the bases for both, but the release of the Alpha ROS Jacket takes things to the next level. With limited edition colors, this model of the Alpha ROS Jacket captures the performance we expect from Castelli, along with an exceptionally stylish and elegant aesthetic.

The Alpha ROS Jacket is ready for rain or shine, with its two-layer construction that separates thermal insulation from wind and waterproof shell. The front offers a double-opening so you can ventilate without exposing yourself directly to the frosty chill. With two-layer construction, Castelli enables each layer to do their job to a higher degree, so Windstopper can keep its focus on sealing out water and wind, keeping the thermal layer dry so it can excel at regulating temperatures. The inner layer provides thermal warmth that wicks away perspiration and allows heat dissipation when needed, so your core temperature can be regulated and you're able to put down the power on long climbs without overheating.

Shielding you from the elements, Gore's Windstopper membrane is reinforced with YKK Vislon waterproof zippers and selective seam sealing. By being selective with seam-sealing, Castelli is able to maintain great dry-weather riding qualities on the Alpha ROS Jacket, without compromising water protection. Castelli won't make the claim that the jacket is 100% waterproof, but it does present the jacket with confidence to stand up to most cold and wet riding with resilience.

With a form-fitting cut that's much like a jersey, the jacket leaves little room for drafts or excessive fabric that flaps in the wind behind you. The cut is designed for in-saddle comfort, so you might notice the chest feels a bit tighter than normal across the chest when off the bike; however, on the bike the design is built to accommodate your arms, shoulders, and back when you are in the drops, eliminating extra fabric in that position. Since the design already features 2-layers you often won't need more than a baselayer to remove the chill, depending on the day's weather and your own preference. The jacket can span temperatures ranging from 23-to-50 degrees Fahrenheit, but—again—that depends on how hot your engine runs.

  • Pedal on through wind and rain in this cycling jacket
  • Limited edition colorway stands out in a crowd
  • Blocks wind and water with Windstopper 150 membrane
  • Insulating midlayer unzips separately for heat dumps on climbs
  • Race fit eliminates excess material and cold air drafts
  • Breathes and wicks away sweat on long climbs
  • Raw-cut hem and cuffs and comfort and improve fit
  • Castelli's revolutionary all-weather race kit continues to evolve

Tech Specs

[membrane/laminate] Windstopper 150, [face fabric] 100% polyester, [liner] 90% polyester, 10% elastane
Waterproof Rating:
double-front opening
3 rear, 1 zippered side
Claimed Weight:
[large] 515g
Recommended Use:
road cycling
Manufacturer Warranty:
1 year

Size Chart


Men's Apparel
Chest 36.2in
Waist 31.5in
Hip 37in
Inseam 31.9in
How to Measure:
For best results, take measurements over your underwear.
Measure under your arms, around the fullest part of your chest.
Measure around your natural waistline, keeping the tape a bit loose.
Measure around the fullest part of your body at the top of your legs.
Using pants that fit well, measure the crotch seam to the bottom of the leg.

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Avg. ride time: 4h 27m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Performs as promised

  • Familiarity: I've used it several times
  • Fit: Runs small
  • Size Bought: Large

I've been very pleased with this purchase, primarily because the product works as advertised. I have a few other cold weather jackets, but nothing that works as well as this one in providing good warmth, moisture management, wind and water resistance, and good fit with other parts of your kit.

Warmth: have ridden into the low 20's in Northern Virginia weather with a long-sleeve baselayer underneath and stayed plenty warm. The usual problem areas on most jackets are the arms, they start out warm but get cold as you start sweating underneath -- not so with the Alpha.

Moisture management - This is why your arms don't get cold. The multiple high performance materials around the arm let moisture escape.

Wind and Water Resistance - The dual-layer concept allows you to control the balance of airflow on your torso much better than traditional vent zips by ensuring that you still have some breathable insulation in the direct wind path. That pulls away excess heat and moisture over a wide range of needs -- fully zipped at very low temps, and much more open as you start working harder or the temperature climbs. Water resistance is similar to a Perfetto/Gabba jersey. It will hold off a mist throughout your ride, but don't expect it to keep you dry in a steady rain for more than about an hour and change.

Fit - The fit is typical for Castelli (i.e., runs small), I wear a medium in most race-fit jerseys (6'2"/168lbs), and a large fits me snug, but with room for baselayers underneath. Unlike some other jackets, the sleeves are snug enough to stay put underneath multiple types of winter gloves (fully insulated or thinner wind-proof style), yet don't feel constricting. The extra material on the back of the neck is a nice addition to a spot that frequently gets cold, but doesn't get in the way of a neck gaiter or balaclava.

In short, at a price much lower than a trainer, this jersey will let you ride in a much wider range of conditions than you thought you could.