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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
  • Castelli Alpha Ros Jacket - Men's
  • Castelli Alpha Ros Jacket - Men's
  • Castelli Alpha Ros Jacket - Men's Back
  • Castelli Alpha Ros Jacket - Men's Back
  • Castelli Alpha Ros Jacket - Men's Back
  • Castelli Alpha Ros Jacket - Men's Back
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CastelliAlpha Ros Jacket - Men's
Sale $314.99 - $349.95

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




















































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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Amazing jacket!

  • Familiarity: I've used it once or twice and have initial impressions
  • Fit: Runs small
  • Size Bought: 3XL

Absolutely love this jacket. I have worn it only once in 46 degree temp in 12-15 mph winds. I only had a short sleeve base layer t-shirt underneath and was more than comfortable. Prefect Castelli fit.

Alpha RoS jacket

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

I've worn this jacket twice: 1st- 46 degrees w/ light drizzle to light rain. I was not only warm but also dry; 2nd- mid 50s with cool-cold breeze. I opened the jacket zipper on climbs, arms were a little warm but fine. So far I am very impressed. I wear my Pefetto jersey on 50s temp rides and now I'll wear my RoS jacket in low 50s and below. I really like both jersey and jacket.

The Best Kit

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

Usually buy Castelli. Sizing is perfect. Race cut with performance in mind. It is warm. It is form fitting. It sheds water. I am extraordinarily picky with cycling kit. And this is the best piece of cycling kit i have ever worn. If you knew me, you would know how big of a deal that statement is. So, if you plan on pedaling hard, you are performance oriented, and you care about style, form factor, comfort, and having everything while sacrificing little to nothing, then this piece is for you. If that is you, then get this. As far as Castelli sizing goes, this is not too small. True to size.

Well-made jacket

  • Fit: Runs small
  • Size Bought: Large

I bought this jacket near the end of the winter season, but had the chance to wear it under race conditions. The jacket was everything I hoped it would be. It fit snugly (fit advertised to run small) but not too tight; it felt almost like a second skin. I was comfortable throughout the race (28-35°F) and the fabric shed the falling snow easily. The zipper was easy to operate with gloves on and the front zipper pocket was handy for food. The inner vest provides protection when the main zipper is used to control body temp. Very happy with this jacket!

No-regret purchase

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

This is truly a great jacket which managed to shorten my indoor season by several weeks a year (I live in DC). The inner/outer jacket setup works well when encountering climbs and such. I combine it with the Rosso Corsa thermal. Yes, it's pricey but this jacket will get you out on your bike more often - and isn't that what it's all about?

Great jacket!

  • Size Bought: Medium

This is my go-to jacket for cold weather rides. I’m very happy that I purchased it. Excellent quality all around.

Simply Great

  • Familiarity: I've put it through the wringer
  • Fit: Runs small
  • Size Bought: medium

This jacket is awesome. It is a great jacket on those really cold days. It pairs well with the Polare bibs. It is light yet pretty warm. It is good in temps down to 20-degrees here in Utah. I personally really like the vest feature. It is great to unzip the main layer while climbing, then zip it back up while you climb over the top of the mountain. One of my favorite jackets on those cold days.

One Impressive Winter Jacket

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

Sadly this is just an initial impression as the weather has not gotten cold enough to truly test this jacket. Quality is excellent. Castelli has had some issue with seams coming apart on some pieces but everything is very nicely sewn on this. Design also is quite impressive - every part of the jacket has been carefully considered to ensure a perfect fit with temperature regulation and weather resistance. The inner sewn in vest adds some extra warmth and allows the outer zipper to open up during the climbs for ventilation without the jacket flapping all over and letting in cold breezes. The sleeves are the perfect length and tailored to fit into gloves. The collar is a nice height, the pockets are accessible, and there are reflective accents in unobtrusive locations. Windstopper panels are on the front and cozy fleece is placed everywhere else to vent heat when you're riding hard.

I found the fit excellent but did size up a good bit. I normally wear medium in more American sized brands like Pearl Izumi and Louis Garneau and size large in Castelli tops. A large in this jacket certainly would have worked but I chose an XL for a little bit more room for layers on the coldest of days and am still happy with the fit. So I'd say runs true to size for race fit Castelli.

Worth the Investment

  • Familiarity: I've put it through the wringer
  • Fit: Runs small
  • Size Bought: XL

Bottom line: not cheap, but well worth the investment (buy nice vs twice).
An incredible piece of garment technology that performs in every aspect. True to the ROS name, feels cozy in every possible cold weather condition (freezing, windy, rainy). I've used it at temps in the 20s with a single winter base layer (Assos winter skinfoil).

Love the many well-thought out details: smart collar design that keeps a snug (but not tight) fit designed around the neck (where it gets cold) to work with a more aggressive position on a road bike, sleeve finish to integrate with gloves, long back to protect from cold/wet, snug cut that may feel strange standing up straight, but perfect once in the saddle.

As always with Castelli - one size up.

Great Jacket - Typical Castelli Sizing

  • Familiarity: I've used it once or twice and have initial impressions
  • Fit: Runs small
  • Size Bought: large

Used the jersey twice in 30 degree weather; very comfortable and really keeps the cold out. I'm 6'4" and normally go with a large jersey, but Castelli is known for their sizes running small and this jacket is no exception. Got an XL and its snug, but I really like it.


  • Familiarity: I returned this product before using it
  • Fit: Runs small
  • Size Bought: X Large

Bought the jacket as a Christmas gift to my father but it was too small. Material is great and the jacket is truly superior to others.

One stop shop solution!

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

This is my winter cycling solution...rain, shine, wind and I picked orange to be totally visible on the road! Best investment I have ever made. Highly recommended. The true test was a couple 2-3 hour rides in 35-39 degree cold rain. It kept me warm in that worst possible chill condition with a merino wool base layer.

thank you for the great review!

Best jacket ever

  • Familiarity: I've used it several times
  • Fit: Runs small
  • Size Bought: 2xl

This jacket do everything they said, I used with Flanders baselayer is warm at 37 degrees

Size Size Size

  • Familiarity: I've used it once or twice and have initial impressions
  • Fit: Runs small
  • Size Bought: XL

I read a lot of reviews of this jacket and decided to take the plunge (full disclosure I bought the limited edition grey version but figured this version will be around awhile, so I am putting my review here). I normally wear a size Med in just about all clothing. I am average slim athletic build, meaning I have shoulders and a chest from years of doing sports beyond cycling. I am not Euro pro thin, hipster thin, nor cross-fit bulky. I decided to buy a Med and Lg to test and tried on the Lg first when it arrived. I felt just shy of being a sausage. Even with a short sleeve base layer it felt snug. Stuffing a jersey in as well was doable but I questioned if I'd really be comfortable on a long ride. I decided to order an XL and its night and day. It is not baggy, but just a bit of extra material makes all the difference. The sleeves are still the right length, but the tail is a little long in back. In a riding position, that just gives you more coverage.

The quality of materials and construction are superb. Really looks good. Bottom line though: if you want aero-sleek with not much extra room, size up one size. If you want flexibility with your performance, go up two sizes.

Ditto on size. Bought an XL and doesn’t come close to fitting. I can’t imagine they make a size that would fit me at 6 feet. Crazy small.

Too Small

  • Fit: Runs small
  • Size Bought: Large

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

for Castelli sizing, this is pretty true to size. It's not nearly as small as the Aero 6.0 series jerseys.

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.

how well would this jacket pack down? back jersey pocket?

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.

how well would this jacket pack down? back jersey pocket?

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.