Castelli Alpha ROS Jersey

I don’t know what Castelli expect in terms of pronunciation of ROS. So I keep envisaging him from Friends. But it’s just Castelli’s acronym for Rain or Shine. Which is pretty fair and, also, pretty hang on wasn’t the old one good for that? It was exceptional in foul weather, far more so than Castelli gave credit for. Read my original review here. And, of course, like the old one, there’s also a jacket. That too gains the ROS moniker so I guess we have something which is good in warmer rain or shine and something for use in colder rain or shine.

So, I guess the first question to be asked is, what has changed? The answer? A little, not a lot, but some of it is arguably significant. As before, the main body of the jersey remains Windstopper 150 on the front and sleeves. That’s a full on but pretty lightweight windstopper. There’s no lining per se, but let’s come back to that, so you will need to tool up with a suitable base layer. Again, being a Gore windstopper fabric, it is inherently waterproof. Rain can’t really get through it but it can get round it and prevent moisture from escaping. So sometimes when you feel a bit damp, that’s you, not the rain. And there are still seams so water will eventually find a way.

The inner gilet is still made from ProSecco Strada, a waffly lightweight fabric. The previous version appears to be Stratus rather than Strada, but I don’t think there’s any actual difference. The most significant difference is round the back. So the Nano warm fabric is replaced by Nano Flex Xtra Dry. This isn’t just a name change, it feels quite substantially different. It’s similar but appears slightly more heavyweight to that found in the Perfetto Light jersey. Effectively it’s a breathable mesh coated with a DWR nano repellent which prevents water from getting in. And I have to say that in its deployment in the Perfetto and Alpha it’s the stuff of witchcraft. How much it repels in two years time will be interesting to see. But, for now, it simply beads up water and chucks it off. That would be problematic if the rain pockets were fully sealed, but Castelli have dealt with that and added drain holes.

The shoulder seams are now externally taped as well. But the overall effect is a little limited. That is the main ingress point on most jerseys given the angle of the jersey when you sit on the bike. It can still leak in just below the seams and on the arms too. But it’s a welcome and visible addition.

Size wise, it’s identical to before, that is to say, Italian. So I need an XL, where I need a Large in most other things. That’s on a sub 40″ chest. RRP is actually a bit bonkers. £230 full price £190 most of the year, currently around £150 and with little sign of dropping to old Alpha sale prices. That is a lot of money. That’s Assos ih.habu money which is a lot of jacket for the money. Mine was a little more sensible, a price reduction to £125 at Evans combined with a 20% post Xmas code and it’s £100, half price. For that it’s an absolute bargain but I can’t help think that it should be pitched at £175 RRP and usually around £149. That’s particularly so as the ROS jacket is a ‘mere £50 more’ and offers a lot more function if not versatility. So, let’s have a look.


It’s pretty similar in look. Colours are better, or worse, depending on your POV. So there’s black, and light black. There’s no mirage anymore, which is a good thing. I quite like the light black (called anthracite) with its orange shoulder taping. But there’s nothing really eye catching apart from Wiggle’s exclusive orange one which commands pretty close to RRP. A mis-step perhaps, brighter colours would be better. The central arm stripe appears to have moved inwards so you can’t see it as prominently, but it’s there. The underarm section is more soft shell than not now. So there’s added protection in that area. The giant rubber band is the same, the zip is excellent and the fit is just as it was before.


The back does look a little different because the main body colour continues in the pockets where, before, it was always black, unless you buy the black one, natch. It’s a neater look IMO and provides, at least in the blue one, a bit of contrast. There are no valuables zips at the back but there is one at the side. Reflectives are better in that they actually exist now, a small amount, but a welcome addition.


The arms have changed a little too. As stated the central section moves around a bit and the new rose cut cuffs first seen on the Potenza jersey make a nice return.


The gilet section remains similar despite the slight name change. You should just be able to make out the fleece backing on the nano flex fabric that makes up the rear section.


Remember that the gilet section is merely a front flap and that the sleeves are single lined. Step up to the ROS jacket and you gain full windstopper protection and lined sleeves.


The new valuable zip is placed on the waist section. You won’t get a phone or a wallet in but cards, coins and keys fit pretty comfortably.


And those taped seams can be seen here. They’re ok but inevitably, given their overall lack of coverage, they don’t really offer a huge amount of extra protection. But they don’t cut down on articulation either. This isn’t a rain jacket, but it does a pretty good impression of it sometimes.

Castelli score this as 4/5 across the board now for wind and waterproofness, insulation and breathability. It scores 3/5 for weight. But it still weighs very little indeed. If you want comfort and insulation this is your boy. And here’s the kicker. The only thing that the Perfetto (previously Gabba) gains is more windproofness yet, Castelli say, it loses out on insulation to the Alpha. Both are rated the same in relation to rain. Hmm, for me the Alpha is just as windproof, if not more so, clearly better at insulation and seems, so far, to perform just that little better in the rain than (already excellent) before. It does seem to have been incrementally improved. A bit better in the rain, a bit more capable of getting to lower temps, just as good at higher temps and oh so comfortable to wear. It’s good to 5 degrees with a base layer, chuck a gilet on and you could go lower. It’s good at 15 degrees. It’s great in drizzle, it’s great in rain. I wouldn’t set out in driving rain but, hey, that’s what Zwift is for, right?

And so it becomes one of those pieces that you should have in your wardrobe just like the old one. If you do have the old one I wouldn’t rush to replace it. If you don’t get this. It’s still not exactly a bargain but have a google and you should get a deal. It’s quality and will last for ages. You can ditch the rain jacket, most of the time. You can ditch quite a lot of stuff actually as this is as comprehensive an all rounder as it ever was.


11 thoughts on “Castelli Alpha ROS Jersey

  1. Looks like Castelli have improved the stitching where the pockets meet the back; my Alpha has started to rip a little at those points, so it looks like another improvement.

    Liked by 1 person

    1. I had been checking out this jacket for a while and waiting for a sensible price and then i found galibier.
      If you want a very similar jacket that does have the thermal material all round that will go below zero then checkout galibier’s mistral pro.
      At £80 its absolute steel, an amazing peice of kit even if you can afford the more expensive brands.


  2. Thanks for the review! I’ve got a few of the older style Alpha, and while they are great one of the bugbears I had was that the roubaix used on the rear panel was pretty insubstantial. How would you describe this new material? I don’t have a perfetto light jersey to compare it with, but I do have a perfetto vest – is this new material similar to the material used on the back of the vest?


  3. Not considering price, if you could only have one jersey to cover variable conditions between 8-14oC would you take the Alpha or Perfetto, or would you consider s/s Gabba with arm warmers or something else ?


    1. 8-14 I think I’d always take the Alpha jersey. It can be a little warm at the upper end. I’d take the Perfetto last each time because the fit isn’t right, good as it is. Otherwise a SS Gabba is always better, IMO, than a LS one


  4. Not considering price, would this or the Perfetto be the best option for sub-3 hour steady riding in variable conditions between 8 – 14oC or should a s/s Gabba be considered ( or something else )


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