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CastelliAlpha RoS Jacket - Women's

Sale 20% OffCurrent price:$279.99 Original price:$349.95

Item # CST00JB

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Item # CST00JB

Alpha RoS Jacket

We're well aware of the additional hardships and discomfort associated with riding during the winter months. We certainly don't want our apparel to be our excuse for not getting out, so if you're in the market for a thermal jacket that offers excellent protection during times of precipitation, take a look at the Women's Alpha ROS Jacket from Castelli. It blocks the weather, but the outer layer and insulating layer are separate, so you can choose how much insulation and protection you need, even mid-ride.

Part of the reason dressing for winter riding is so difficult is that we need to stay warm for most of the ride but if the pace picks up or there is climbing involved, we'll quickly turn into a sweaty mess leaving our muscles feeling stiff and us shivering for the rest of the ride. From working with pros and from other garments it's created, Castelli learned that a jacket with wind and water protection was necessary, but that protection could occasionally be too much. The Alpha ROS is prepared to pamper you with warmth and dryness this winter riding season.

Castelli uses the requisite Windstopper 150 membrane and thermal insulation in the Alpha, but does so in two detached layers allowing each piece to do what it does best and further regulate temperatures while climbing. As you heat up, unzipping the shell lets the wind hit the jacket's thermal layer cooling you off gradually instead of with an unmitigated arctic blast. The thermal layer insulates while breathing quite well so you get more of a thermostat and less of an on/off feel. It's able to manage moisture continuously as you summit the climb keeping you dry as possible. At the top, simply zip up and head down without teeth rattling or shivering throwing you off your lines through corners.

On the plunge down, you'll appreciate the Gore Windstopper 150 membrane. The windproof three-layer, four-way stretch knit fabric with a water-resistant DWR coating keeps wind out and precipitation at bay. You'll want this jacket just as much on solo base mile rides through the valleys as you will on tempo group rides over rolling terrain. The ventilating back panels resist trapping heat to further promote cold-weather comfort.

The Alpha ROS has an aggressive race fit more reminiscent of a jersey than a jacket, and it leaves just enough room for a base layer underneath, which is all you'll really need since the thermal layer does such a wonderful job of providing warmth. Castelli cuts the jacket to accommodate your arms, chest, and shoulders while you're in a riding position. The only disadvantage is it may feel tight across the chest when you're off the bike, but, once you're back in the saddle, it all-but disappears.

The Alpha ROS features raw-edge construction at both the waist and wrists. This allows the sleeves to integrate cleanly with gloves without bunching fabric, and it keeps the hem in place. The waistband also features silicone grippers, anchoring it and maintaining coverage as you ride. The collar is engineered to avoid creating a wind chute behind your neck while you're in the saddle, and three jersey-style rear pockets add easy access to nutrition mid-ride. A final, zippered front pocket adds an element of security to keep your valuables safe.

  • A race cut cycling jacket for the heart of winter
  • Windstopper 150 membrane shields against the elements
  • Maintains breathability and stretch for comfort
  • Outer and thermal layers unzip separately
  • Raw cut hem and cuffs reduce bulk and lie flat
  • Three pockets supplemented by a zippered side pocket
  • Race fit is sleek with just enough room for a base layer
  • Recommended for temperatures hovering around freezing

Tech Specs
MaterialGORE Windstopper 150
Waterproof Rating10,000mm
Ventingdouble front opening
Pockets3 rear, 1 zip side
Reflectiverear pockets
Recommended Useroad cycling
Manufacturer Warranty1 year


Women's Apparel












































Note: Castelli has a "Euro" slimmer fit. We suggest ordering at least one size larger than your normal US size.
How to Measure:
For best results, take measurements over your underwear.
Measure under your arms, around the fullest part of your chest.
Natural Waist:
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.

What do you think about this product?


>Rating: 4

OK for the price I paid

True to size

I got it on sale, and for that price it's good. It's a super warm jacket (I'm always cold!) and should be worn at or below 50F. As mentioned before me, the fit is awkward. Loose in the belly, and tight in the arms and shoulders. I'm 5'6", 110 lbs, 82 cm chest, 64 cm waist and 84 cm hip. Normally XS in Castelli. Got both the XS and S in this jacket, but sent back the S, as the mid-section was far too loose and only offered marginal gains in the arms. Kept the XS, hence true to size (see picture). I suppose you shouldn't need to wear much under the jacket anyway, it's that warm. Criticism for Competitive Cyclist: The picture is not accurate. Expected a yellow detail (I have a yellow bike) but got orange.

>Rating: 5


I've put it through the wringer
Runs small
Size Bought
5` 5"
110 lbs

I didn’t think Castelli could improve on the Alpha Ros, but they have. This is my third jacket of this kind, and this year’s changes make the jacket perform even better in extreme cold. The jacket breathes better for more warmth with the redesign of the inner layer not being stitched down in the back-there is a noticeable difference. The slightly longer back of the jacket covers more to keep you warm and protected from the wind, and the redesign of the sleeves makes it easier to get on and off and seals better around the wrists. The slightly taller fleece tab on the collar keeps more cold air away from your neck, and there is nice room in the shoulders. The new colors are great-hope they bring back the yellow which is great for visibility. I usually wear a small in Castelli jackets, and this one fit the same.

>Rating: 3

Wanted to like this jacket

I returned this product before using it
Runs small
Size Bought
5` 6"

I got my usual size in Castelli. Unfortunately, the shoulders and arm areas were too tight for me. The rest of the fit was good.

>Rating: 1

Fabric is nice, fit is not

Size Bought
5` 9"
147 lbs

I’m 5’9” 147lbs, and ordered the XL based on the size chart. From the waist up it fit great but the waist down was horrible. The jacket hit well below my waist almost to mid-hip. Not only that the entire black bottom piece was so loose and huge that I had at least an extra 8” of fabric. Even if I went down one size, the bottom fabric is not hemmed, nor does it have eleastic, it’s just a single thickness that is supposed to provide a smooth windless finish. To get a tight fit on the bottom I would have to drop 2 sizes and then the top half wouldn’t fit. If you are a lady with larger hips it might work for you. Color and craftsmanship is good, just weird fit. Returning it.

>Rating: 5

Awesome jacket

I've used it several times
Runs small

I am 128 lbs, 5’5”, I usually am size small. But in this jacket small was too small. I got a medium instead. This jacket really does what it says. I am the type of person who is always cold. I wore it in 32 degree Fahrenheit weather. I wore a base layer and tank top. Also had fleece neck muff and gloves. Once I got going I was comfortable, not cold. I have also worn this jacket with only a tank top on a 52 degree Fahrenheit day. I’m sure I’d be fine if it got even warmer and I wore it unzipped. The pockets, fit, sleekness and style of this jacket are superb. Was more expensive that others, but very much worth it. This jacket can take me from fall, through winter and into spring. It fits like a cycling jacket, close to body, fitted, not exactly super snug like a cycling jersey would be, this is not a problem for me.

>Rating: 4

Nice, but not perfect for me

I've used it once or twice and have initial impressions
Runs large

I wore this jacket for the first time the other day in fridgid temps with a long sleeve base layer as well as a thermal long sleeve jersey. I was comfortable while riding, but unfortunately am not completely loving the fit off the bike (maybe there is extra room in the mid section to allow for the added attached inner warm fabric to fit properly under the jacket?). Thinking it is more of a relaxed fit rather than a racer one. Bought the medium (5’3”, 117 lbs.)