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  • Castelli Alpha Ros Jacket - Men's
  • Castelli Alpha Ros Jacket - Men's
  • Castelli Alpha Ros Jacket - Men's
  • Castelli Alpha Ros Jacket - Men's
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CastelliAlpha Ros Jacket - Men's

Item # CST00IC

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Item # CST00IC

The alpha dog in winter.

Cold-weather cycling creates a conundrum. Naturally, we want to stay as warm as we can but if the jacket doesn't breathe well and we get too hot, we'll begin to sweat. This isn't a good thing especially if we start descending and the wind chill cools our damp jacket. To truly stay comfortable, it is imperative to have something that keeps the elements out yet regulates body temps. Leave it to the wizards at Castelli to produce a piece of kit that defies our expectation of what we know of a winter jacket. The Alpha ROS Jacket is ready for Rain Or Shine and is there to help make all of your winter rides more enjoyable. What's really nice about this jacket is that it works so well, it inspires us to go ride even in the worse conditions.

The Alpha ROS Jacket's two-layer construction separates the thermal insulation layer from the wind- and waterproof outer shell. A double front opening to diffuse the cold air when you open up to ventilate on the climbs and prevent overheating. The thermal layer is breathable and is able dissipate heat easily so temperature regulation is an all over affair and not just confined to small pockets. If things heat up even more, the thermal layer can also be zipped down. By crating two layers, each can do their job more efficiently. The thermal piece adds warmth and is more breathable while the outer Windstopper fabric keeps you dry and keeps the chill out. This results in you being less clammy at the top of the climb, and with a quick zip up, you can descend shiver-free since you'll be warm and dry.

By using Gore’s new Windstopper light rain-resistant membrane and DWR treatment, selective seam sealing, careful seam placement and construction, and a waterproof YKK Vislon zipper the jacket is essentially waterproof without compromising characteristics making it such a great dry-weather jacket too. No matter the weather report or what kind of ride or training you have on tap, this jacket pretty much guarantees a dry and warm experience.

The Alpha ROS features raw edges at the waist and wrist—a trend defining top-end gear in the cycling industry of late. Raw edges mean that the hem and cuffs don't contain elastic inserts, so they allow for complete freedom of movement and fit nicely under gloves' cuffs. The jacket never rides up, so no tugging it back into position if you have spent time doing an interval in the drops and now you are recovering on the tops.

The fit of the Alpha ROS Jacket is actually more akin to that of a jersey. Since it does come with its own thermal layer, base layers of varying degrees, depending on the temps, can be employed customizing the jacket to the conditions. Castelli rates the optimum operating temperature range between 23- to 50-degrees Fahrenheit. The Italian brand is typically conservative with its temperature estimates, so that huge range speaks volumes for the jacket's versatility.

The Alpha ROS Jacket's aggressive cut rides very close to your body. Stretch fabrics with advanced patterning make for an excellent snug fit that still accommodates a wide range of body types. You will notice a tighter feel across the chest when off the bike; however, once you're clipped in and rolling, the Alpha ROS is designed to accommodate your arms, shoulders, and back as you reach for the handlebars, so there's little or no bulge or baggy material. The articulated collar is cut to prevent wind from catching it, and the shell and thermal layers' zippers are offset to eliminate bulk and allow easy access on the go. It has three rear pockets and a zippered pocket in the rear and the front.

  • A next-generation cycling jacket for cold and wet weather
  • Windstopper 150 membrane blocks wind and water without stifling
  • Insulating thermal midlayer zips separately for targeted warmth
  • Race fit eliminates flapping material during tempo base miles
  • Maintains breathability to manage moisture during hard efforts
  • Raw-cut hem and cuffs add comfort and improve fit
  • Castelli's revolutionary all-weather race kit continues to evolve
Tech SpecsSize
Tech Specs
[membrane/laminate] Windstopper 150, [face fabric] 100% polyester, [liner] 90% polyester, 10% elastane
Waterproof Rating
double front opening
3 rear, 1 zip side
rear pockets
Recommended Use
road cycling
Manufacturer Warranty
1 year


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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Too Small

  • Fit: Runs small
  • Size Bought: Large

Runs smaller than i thought. Too tight, so have to return

Avg. ride time: 6h 40m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Best cycling jacket I ever had!

  • Familiarity: I've put it through the wringer
  • Fit: True to size
  • Size Bought: Small

Can't go wront with this jacket, it feels like I never overheat but also never get cold. I use it everyday during the fall season to commute at down to -10C and never have any problems! The fit is really nice on the bike, but don't try to use it for something else like hiking, the cut is really made for cycling and it will feel very tight and uncomfortable otherwise.

Worth Every Dollar

  • Familiarity: I've used it several times
  • Fit: Runs small
  • Size Bought: 3XL

The Castelli Alpha Ros Jacket does a fantastic job of keeping me warm and dry when it's below 40F. For me, a race tight fit is not essential, so I ordered the 3XL and am pleased with the fit.

Awesome jacket

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

Used it vatious times, but the one time worth mentioning is, i used during a race this winter, Temp was about 30 degrees, night time, after the second lap it started pouring and I mean pouring rain, (like you couldn't draft the person ahead of you due to the roost cooming off their tire, pouring) for the next 6 laps the sky just let it all out, I was dry, everyone that dressed in just a race kit was freezing, those that bundled were overheating and wet, some didn't finish. This jacket kept me super dry and warm. Just in not feeling like an ice cube that night, it was totally worth every penny.

Warm, Simple And Sleek

  • Familiarity: I've put it through the wringer

I've been extremely pleased with the Alpha Ros Jacket. Winter training is sub 32 F degree weather is made simple knowing you'll keep warm and dry. I picked up the bright orange variant knowing it would contrast well in snowy conditions.

Sizing and fit remain consistent with Castelli's Euro fit and is not bulky at all. This a very versatile piece, the key is to vary your base layers based on the temperature you're riding in. I'll use a sleeveless summer base layer for warmer days or a heavy wool baselayer for the coldest of days.

Overall, this is my go to jacket during the cold winter months, and I think Castelli has done an excellent job on this piece.

Avg. ride time: 5h 48m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Quality Piece

  • Familiarity: I've used it once or twice and have initial impressions
  • Fit: True to size
  • Size Bought: XXL

I bought this as I wanted something that fit tighter than most traditional winter jackets. I almost always struggle with sizing, but, this is a nice, tight fit and allows for a base layer or two, without being baggy. I've only used once in 25-27 degree weather with a Castelli Flanders base layer and found that I was warm throughout my ride. The jackets seems to breath pretty well, but, my base layer was certainly wet by the end of my ride. The bright orange is a nice contrast to most of my gear and hopefully makes me more visible while riding.

Avg. ride time: 2h 10m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.


  • Familiarity: I've used it once or twice and have initial impressions

Pros: Dual layers for easier temp moderation.
Cons: Many sewn parts that are prone to fail. Not as warm as expected. Inner layer not removable.
Fit: Form fitting closer to race fit than casual fit.
Summary: I purchased this specifically for riding in colder temps (< 32 degrees). Tried it out this morning and it was exactly 32 degrees. First 10 minutes I was cold. After some moderate pedaling, I warmed up to a comfortable temp. My base layer was an Under Armour ColdGear Evo Long Sleeve Compression Mock. Any temps lower than 32 degrees and I'd consider another layer.
By comparison, I also have the Senza 2 jacket. The Senza 2 is definitely more bulky and more of a casual fit, but it feels warmer. The Alpha ROS does have the benefit of unzipping the outer layer for more temp moderation.
Overall, I wish the Alpha ROS was warmer, was more of a casual fit, and didn't have so many sewn pieces that will eventually fail. Would I purchase it again? Probably not. My biggest concern is the durability of all the sewn pieces.