Castelli Alpha ROS Cycling Jacket - AW18
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Code: CS1750285
Castelli Alpha ROS Cycling Jacket - AW19

The Castelli Alpha ROS jacket provides insulation from the cold while preventing you from over-heating thanks to its excellent breathability. This versatile jacket will keep you warm in cold weather as well as keeping you dry thanks to its effective waterproof outer and sealed seams on the shoulders with double stitching to stop water creeping in on longer rides. With a clever ‘Alpha construction’ Castelli have been able to produce a cycling jacket with two separate layers built in – one providing protection from wind and rain and the other providing insulation from the cold. 



  • Windstopper outer – for breathable protection from wind and rain
  • Sealed seams on shoulders
  • Separate insulating layer
  • Partially covered YKK zipper
  • Raw edge waist lies flat and moves with you
  • Raw edge wrist cuffs – prevents interference with gloves
  • Stretch fabric for close fit
  • Ventilation on back
  • Castelli text gripper at waist keeps jacket in place
  • 3 rear pockets with drain holes

Sizing Information for Castelli Clothing:

Castelli Size Charts

Mr Stevens Excellent jacket good quality kept me very warm yet to try out in wet but very pleased with purchase and Merlin service
Greg A supreme performing winter jacket for those cold winter mornings in Canberra Australia
Saunders Excellent quality. Comfortable to wear. Little tight across the chest. Ordered medium despite some measurements in the S and still a bit tight. Otherwise perfect.
Mr Cubbon As expected from Castelli its of the highest quality. The fit is great and the breathability is of the highest level. Not had chance to test the water resistants yet but I know it won't let me down.
Mr H Awesome jacket! Initially I was a little disappointed as I’d expected a thick fleece like garment but on wearing this product I’m so impressed. I’m 5’7” and bought M. Used it in temps around -2to+7 and it works a treat. Pricy but worth the money. 5star product.
Mr Ademosu Probably the best thermal jersey out there. Nice and toasty @ 2 degrees with just a base layer. Well done Castelli
Philip This is a seriously decent piece of kit of fantastic quality and feel. I'm built skinny, 179cm in height, 92cm chest, 63 kilos and Large fits perfectly. I first wore this on a 30 mile ride in 3 degrees with a base layer and was too warm, its perfect for me 0-7 degrees without any additional layers and the ability to open the inner vest to ventilate when required. Windproofing is superb and breathes very well. Not tested in heavey rain although it's not intended for that, the trade off you get in breathability out weighs that for me. Love it.
Mr Wong This is an incredible jacket. Wore in 20 degree F(-7 celsius) with flanders base layer and was perfectly warm. The inner vest allows you to unzip the jacket during intervals and stay warm enough and then easily rezip during recovery. Haven't used in wet weather yet so we will see how it works there. I am 5'11 165-170 lbs and needed a large.
Mr Kaye I’ve worn this jacket on two recent 2 hour rides in 6 degrees with wind chill. Kept me toasty warm with only a half sleeve base layer underneath. Castelli have stepped up their quality with this jacket. Outstanding level of garment. I’m a slim 38” chest, size Medium was perfect. Great deal from Merlin.
Mr Pařízek Best winter jacket. Using it around 0°C only with light thermo base layer. Perfect quality. 170cm bough L size.
Mr Pérez Higuera Amazing and beautiful jacket. Excelent fit breathability and versatility
Waldo Jeffers Used this for the first time today with a LS merino base layer for an hour and a half at 5 deg C in steady rain and it was fantastic. Every bit as good as the reviews have stated. Kept me warm and dry for the duration of the ride while my legs (in winter, windproof/water resistant tights) froze. I have always been happy to layer but age is making me feel the cold a bit more so I decided to splash out on this when it had 40% off. It's definitely greater than the sum of it's parts - better than a Perfetto + thermal jersey even though that's pretty much what it is. I am 5'8", 38" chest & 68kg and the medium fits perfectly. The outer layer is comparatively loose fitting but the integrated liner is quite close fitting so anything other than a base layer might be a bit tight, particularly at the arm pits. Size large had the same issue. I may just have an Alan Partridge fat back though. Perfect winter jacket.
Mr Howe Fantastic jacket, as other reviews have said it gets a bit hot at >8c but perfectly wind proof, warm and waterproof for winter rides.
Mr Lange Just one word: Perfect
Mr Martinot Absolutely great jacket, quality in every little detail. Fits on the small side, I'm 1.87, 80kg, usually XL for italian cycling apparel, but this jacket fits just great in XXL (with the possibility of a layer underneath)
Edward Second one Ive bought, exceptional piece of clothing, Used it on a 400k 15hour Festive 500 spin that started at 6C and finished at -2c, worn with a base layer, kept me warm and dry. Worth every penny
Mr Erjomaa Already had a lighter version of this Alpha ROS jacket and this is awesom product. Now going for the winter version. I go for 180cm (normal body shape) and XL is the right size while you want to wear something beneath during the colder months.
marcus Great Jacket, warm and windproof. I have not had the opportunity to test the waterproofness yet. I nice fit for my body type, typical Castelli sizing, so size up!
Keith This is a well-designed, well-made jacket with a neat inner waistcoat and easily copes with the advertised temperature range without that sweaty feeling after a 2 hour ride. I am 170cm height, 100cm chest and ordered a size "Large". It is smart, comfortable and a generally smooth "club fit" but light, and unrestricting. So far only worn in dry conditions but ideally described as "Rain Or Shine". Thoroughly recommended.
Gabor IMHO the best winter cycling jacket. It looks a bit complicated with independently zippable interior, but in fact after you are in it, everything looks manageable. With it you can more or less independently regulate warmth AND windproofness.
Mr Vincent Awesome bit of kit. Fine with just a baselayer (I use UA Coldgear) down to freezing . XXL fits me perfectly (I'm 6'4" and 97kg), which I knew from having a Perfetto, and this jacket is the perfect colder weather accompaniment to that. If it's sub 6 degs C then grab the Alpha ROS. Great buy, Merlin performed as well as I'd have expected - they always deliver.
david Probably the best winter jacket available, warm with just one base layer at -1, waterproof and a good fit comfortable
Tim Castelli does it again. The perfect winter jacket that allows me to cycle in comfort down to -5C. Fab!
Mr Cholakov Very good jacket it is working very well. This is my first so expensive jacket but I do not regret. It is perfect.
Mr Kindhag Best ever jacket I have, have a couple of them before, if you want a jacket that can handle moist and rain and cold this is the ONE!
Paul Quite simply the best cycling jacket I have ever owned, beats the winter cold and rain hands down. Great price point and timely delivery.
Herve Brunet I've ordered it in medium previously and it was too small. The design of this jacket is incredibly advanced, with multiple layers, that should let the sweat out while keep you dry. I am 177 cm and 74kg and size L is just fine. As always Castelli runs small
mjr Excellent bit of kit to have - warm and great in the wind and rain
Steve whittington Great piece of kit and well worth the investment. Sizing is unusually generous for Castelli and the XXL fits me like a glove, I'm 6'3" and 93kg. Sleeve length is perfect. Rode yesterday in temps down to 1 degree and didn't feel cold once, not even on long descents, and I only wore an L/S merino base layer. On the climbs opening the zip slightly meant I wasn't over heating either. It rained at the end of the ride and the jacket just repelled it. Best jacket ever!
Drongo77 Great Jacket! Have worn this in several wet cold days now, and very impressed. Have been in heavy rain for 40 mins, followed by light rain for another hour plus, and despite less than 10 degrees Celsius, have continued riding in comfort for another 2 hours with still totally warm torso and arms. Particularly like the tight fitting cuffs and waist, that keep the weather out. Snug fit for slim builds. I am 65kg, 170cm and medium fits nice. Also, after being out in rain for some time, the jacket dries quickly in mild warm room overnight, so fully dry to back up and use next day Only knock is limited colour range - brighter hi viz colour would have made a better choice than the blue, that is not ideal on cold grey wet days. Well worth the money for very warm jacket that copes extremely well in the wet..
Park I'm 6'03" tall and weigh 172lb. XXL is good fitting. This jacket has many good things, good quality and I get a good price
Fernando Pinheiro Great Cycling Jacket Probably the greatest jacket I have ever owned, keeps my core at a comfortable temperature even when riding below zero just use a baselayer and you are ready to go! Size fits small like all Castelli products.
Mikel Very good jacket for winter. High breath-ability, tight fit. Only one base layer needed, even with less than 5 degrees.
Mr Sykes Excellent piece of kit, 100% windproof, highly water resistant and warm. Rode it with merino long sleeve base this week in 2 degrees with 15-25mph winds and continual rain. Proper grim day, but thankful for this jacket. In reality the waterproof was not quite there but we were out for almost three hours (WHY?)........ also worn on dry days down to 1 or 2 degrees and it is fantastic. I bought on recommendation and delighted to pass on. Only wish the Orange was not sold out as that's the winter option right there. If you have the dollar .....
william Good fit and warm, sleeves are a bit long
Mr Reay Ordered this jacket for winter riding and it certainly lives up to my expectations. Used on ride in sub zero temperatures and wind, with only a long sleeve base layer. Absolutely superb, a bit on the pricey side but well worth the money.