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  • Castelli Alpha RoS Light Jacket - Men's
  • Castelli Alpha RoS Light Jacket - Men's
  • Castelli Alpha RoS Light Jacket - Men's
  • Castelli Alpha RoS Light Jacket - Men's
  • Castelli Alpha RoS Light Jacket - Men's
  • Castelli Alpha RoS Light Jacket - Men's
  • Castelli Alpha RoS Light Jacket - Men's Back
  • Castelli Alpha RoS Light Jacket - Men's Back
  • Castelli Alpha RoS Light Jacket - Men's Back
  • Castelli Alpha RoS Light Jacket - Men's Back
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CastelliAlpha RoS Light Jacket - Men's
Sale $184.99 - $249.95

Item # CST00ND

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Item # CST00ND

Alpha RoS Light Jacket

The RoS in Castelli's Alpha RoS Light Jacket stands for Rain or Shine, as in the jacket is wind- and waterproof but also breathes well enough to manage moisture when the clouds part and the sun shines through on a late-November day. Depending on conditions, the jacket is actually well suited to Castellie's suggested temperature range of 46 - 59 degrees Fahrenheit. We don't always trust vendor recs, and we know that seems like an extraordinary claim, but, well, it's an extraordinary jacket. If it's raining and windy, 50 is actually comfortable; if it's a bright winter afternoon, then temperatures in the mid-40s range are fine—though we should disclaim that some of us need a thermal baselayer to push down into the low-40s.

Gore's Windstopper 150 membrane is the key to the jacket's versatility, but Castelli's cycling clothing know-how is why it's ideally suited for serious cold-weather training and racing. Part of that is the inclusion of a rear panel of Castelli's Nano Flex Xtra Dry, a thermal material with a DWR treatment that dumps excess heat, improves breathabillity, and maintains a water-resistant surface across the entire jacket.

The Windstopper layer is separated from a thermal layer across the front panel, so you can unzip the protective shell but leave the thermal layer intact, letting you moderate exposure on long climbs without exposing your bare chest to a frigid, wintery blast. Skiers and alpinists use Windstopper indiscriminately: their goal is to stay warm and dry at all costs. Cyclists' needs, on the other hand, change over the course of a ride depending on intensity, climbing, descending, etc., so we need the protection to change with us in real time. The Alpha solves that problem.

  • Castelli's most versatile jacket for training and racing
  • Windstopper 150 membrane blocks wind and water without stifling
  • Rear thermal panel breathes but keeps rain at bay
  • Separate thermal mid-layer provides targeted warmth
  • Race fit eliminates flapping material during tempo base miles
  • Maintains breathability to manage moisture during hard efforts
  • Raw-cut hem and cuffs reduce bulk and maintain coverage
  • Born near the Dolomites, Castelli knows the needs of cyclists in winter
Tech SpecsSize
Tech Specs
[membrane/laminate] Windstopper 150, [face fabric] 100% polyester, [liner] 90% polyester, 10% elastane
3 season
3 rear, 1 zippered side
rear pockets
Recommended Use
road cycling


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

Love the style, material, but way way way too small. I normally wear L in jacket, XL shirt, bought XXL. Sleeves small and will barely zipped. Does not come in 3XL, but I don't even know if that would fit comfortably. It's going back...

Great Jacket

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

Wore this jacket over a long sleeve Prologo V (size L) jersey on a 46 degree sunny and windy morning on a high intensity ride. I was warm when I started and stayed cool enough the whole ride. The temp was 57 when the ride finished. Well cut to fit me. I’m 5’10 167lbs and would highly recommend this jacket. Jacket size XL.

New Favorite

  • Familiarity: I've used it several times

I know, it's not cheap, but just go buy it and thank me later. I can't find a better piece of cold riding gear -- Castelli got it right. I've rode in light sprinkles into the mid 30s, plus windy, 50+ deg temps. Folks, this thing works and is comfy too -- 100% wind/water protection. Above 50F, I ride w/ the outer zipper open, and it's perfect as you heat up. Think ski jacket pit zips, only much better functionality. Sizing is typical Castelli -- runs small for my non-Euro sized American bod. I can squeeze my 34 in waist and 42 in chest into an 2XL, but I went w/ 3XL so I could get a base layer in there and keep blood circulating. As usual, sleeves are a bit long (all brands).

What a Jacket!

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

I wanted visibility when riding in light rain and mountain biking, I need sunglasses when wearing my orange Alpha Ros! I had tried the Perfetto long sleeve jersey and found my arms and back got cold from sweat that did not evaporate. With more Nanoflex on the sleeves and back, the Alpha Ros is perfect. The front is much more wind resistant than my old Ibex cycling jacket. I don't like the second zippered internal vest, but I can wear it with a light wool long sleeve undershirt and long sleeve wool jersey down to 32 deg F. It is quite tight, even in XXL for my 36


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

This is such a great jacket. It is a very nice technical piece. I personally ride it down to 35 degrees here in the West. It works well with just a baselayer. You really can't go wrong with it. I highly recommend this piece of clothing for the fall and winter days.

So your 6’-2” and bought a small? Really?
Were you born with alligator arms?