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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 $258.99 - $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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Assos ros alpha

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

I’m average size guy and the xxl fits nicely. I tried the xl and it was a little tight around the armpits. I’ve used several name brand pieces of riding gear and this jacket is very nice. Rode today in 40 degrees, cloudy with light wind. I’m using Assos mille s7 tights (m) which are also outstanding! I did need a long sleeve base. I used the craft (m) and never got a chill. I’m not sure I completely agree with the breath ability thing. My base layer was pretty wet but not uncomfortable.

I’m 5’9” 180 with a 33 inch waist, 32 inseam and wear a 40 dress jacket. Buying without trying things on can be tough. Hope this helps.

Castelli Alpha Ros Jacket

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

First, regarding fit, I am 5' 7" and 163 pounds (body mass index of 25). The average BMI for an adult male in the U.S. is 26 and in my opinion, the Alpha Ros jacket is not sized for the average-sized cyclist but one much leaner than average. Almost all of the reviewers that I read (see below) sized up from one to three sizes larger than their normal size. So, I followed the many reviewers' claims about the jacket running quite small and I went up 2 sizes (I normally wear Large). For me, I made the right choice. The jacket fits snug but not too tight. Others should choose size based upon preference.    
Here are the numbers of cyclists of each size of the 33 reviews that I could discern (from Amazon and Competitive Cyclist/Backcountry).
Small - 1
Medium - 4
Large - 9
XL - 11
XXL - 5
XXXL - 3
One can see that a full 60% of reviewers of this jacket chose either a L or XL size. Plan accordingly - this jacket runs very small.
Secondly, concerning functionality I had initial doubts whether a decidedly winter garment without much bulk could provide the essential warmth and protection for which I was looking. The first time that I wore the jacket was at 25 degrees with a base layer and jersey and it worked quite well. At that temperature riding at 20 mph, the wind chill was a bone-chilling 11 degrees. In fairness, Castelli rates the jacket as effective down to 23 degrees. Subsequently, I wore it on several 2 to 3-hour club rides in 30 to 40-degree weather with a single base layer and it effectively blocked piercing cold wind and kept me warm. I feel that it works because it is made with technologically-advanced fabrics. I like the two-piece design in which the windproof outer layer can easily be unzipped to the breathable thermal insulated inner layer when needed to vent some upper torso heat  In my opinion, this design to regulate inside heat is one of the most important features of the jacket.    
Third, I also like the garment design around the neck because it provides additional protection and the three rear pockets and side pocket are all useful. Moreover, the cuffs are well-designed, allowing gloves to easily fit over them and seal off cold wind from entering up through the jacket sleeve. I opted for the red/black Alpha Ros color because it should be highly visible to motorists, it is a welcome addition to my standard mostly-black cycling gear and it is aesthetically pleasing.    
Lastly, the jacket is expensive but it appears very well-made. I consistently ride throughout the year with a local cycling club and have logged more than 7000 miles on the road in 2019. I fully expect this jacket to help me withstand our 5-month winters for years to come. It does the job and I am glad that I purchased it. I rate it five stars.

Amazing jacket

  • Fit: Runs small
  • Size Bought: XL

It's magical how a jacket with so little bulk can keep me so warm! So far, I have worn it down to 35F (measured on the gauge built into the Garmin 1030) over just a turtleneck Flanders base layer, with zero indication that it was anywhere near its lower temperature limit. The two-zipper system works exactly as claimed: unzip the outer zipper approaching an uphill, zip it back up going down the other side, prevents overheating and sweating. The ends of the sleeves are very glove-friendly, a big plus.

The outer zipper was slightly balky when pulling it down from the top so I applied zipper lube to the top few inches.

A small improvement would be to make the inner thermal layer removable (zippers?) so one could clean it without having to wash the entire jacket.

I am XL in all Castelli tops and and XL in this fits me perfectly.

Its $350 list price seems steep until you have used it. Then it seems worth every penny. Still, I was pleased to get mine on sale!

way too small

  • Fit: Runs small

Jacket is well made but way too small. Went with one size larger and it is still too small.

Best cold weather cycling jacket.

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

What took me so long to get this jacket??? Had my first ride a few nights ago and was in 40's. Perfect. Did second ride with it today with just the jacket and a light, long sleeve base layer. Was about an hour from home when unexpectedly a cold rain came. The temp was a little warm for the jacket today, 53 F, but was SO glad I was wearing it. Dry as a bone and warm. At least from waist up. During first half of ride climbing was a bit warm, but easy to cool down with the two layers.

I usually wear size Small..have 36" chest, but got the medium and it's a perfect fit. Did try a small but too tight in armpit area..otherwise good. The medium comfortably allows for heavy base layer when needed, and even jersey as well if it gets freezing. Tried the Assos too, and prefer the Castelli for both fit and function.

Will use for both road and mountain biking. Got it on sale for about $220. Would I spend the full $350 for it? Well, it's worth it, but probably would suggest getting on sale. Now I definitely need waterproof booties!

Flexible and warm

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

Excellent piece of kit, seems well made And can be made useable in warmer temps and colder temps 30-50f. Great jacket and worth the price, almost too warm in the high 40-50f temps but can be easily unzipped to add some cooling. Nice color options as well the orange color is very visible while being stylish and not the typical high vis yellow.

Super warm jacket!

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

Crazy how a jacket so thin keeps you so warm! The technology these days is amazing. 45 degrees with no sun is pretty much the upper limit I think for this jacket. I first used it at 31 degrees and it kept me warm, by the upper 30's to low 40s, It really blocks the icy air when going 20 - 40+ mph. I had the inner base unzipped and had the outter shell partially unzipped so as to not sweat too much. I am 6 feet tall and around 182. based on other reviews, and body dimensions given, I chose the Large, it fit very well except for the armpits. It dug into them even when I test road in front of the house, I went to XL, same thing happened, so I went to XXL and the jacket fits perfectly. I must say, I didn't see much in size change with the 3 jackets other than it felt more comfortable now. Still conforms to the body and is sleek. It works like a regular jersey with the 3 pockets in the back, and it has a zipper pocket in the front as well. Comp Cyclist was awesome, I would exchange and have another jacket in 2 days each time I had to re size.

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.

Nice review. A request to all reviewers: it's a great piece of kit, but what are all your sizes if you have not mentioned them? It greatly helps others to mention your suit jacket size (ie, 40, 42, etc), height, weight, sleeve length, neck, and if you're long-waisted (and do you prefer to wear "Tall" sizing in shirts), etc. What I'm getting at: is this jacket long enough in front/back/sleeves? Is it too snug, too big or just perfect in neck, etc.? Grazie Mille.

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