Castelli Squall Shell review: no excuses for not carrying a waterproof jacket

With the environmentally driven demise of Gore-Tex Shakedry products, cyclists have lost one of the best, most effective waterproof and hugely breathable fabrics available. It had some issues—high price, no stretch, low durability, and lack of colour choice—but many riders could overlook them for its incredible performance. I mention this by way of an introduction as it is inevitable that as brands introduce alternative performance rain jackets, they will be judged against the benchmark set by Shakedry.

Castelli isn’t short of outerwear options, but their new Squall Shell Jacket looks like a potential replacement for how I use my original Shakedry waterproof, which is to say as a windproof/waterproof layer that I carry on every ride that the forecast is less than glorious for. It sits towards the lower end of their waterproof range price-wise, which is no bad thing as cycling gear gets ever more expensive. There are lots of options from other brands on the market too, so how does the Squall Shell stack up?

It is available for men in sizes XS to 3XL with three colour choices whilst women can choose between two colours in XS to XL.

Construction

The Squall is phenomenally light for a fully taped waterproof jacket, with my size large coming in at just 98g. It’s made from a stretch 2-layer fabric that is almost translucent and although it is fully waterproof I think that the clue is in the name - this is a jacket to carry and put on if caught in a shower rather than one to put on at the start of an all-day ride in the rain. Equally, the fabric is such that I wouldn’t envisage wearing it regularly while commuting and certainly not if carrying a backpack as it doesn’t scream durability - hardly surprising at sub 100g. Castelli gives it a temperature rating of +4°C to +18°C, but this is pretty arbitrary as it depends entirely on what you wear underneath it.

There are no pockets to compromise the waterproofness and the full-length front zip is water-resistant. Hem and sleeves are lightly elasticated, with a long ¾ length reflective strip down the centre of the back. The Castelli writing on the sleeve is also reflective but is unfortunately on the wrong side for UK or Australian users to help when signalling a right turn.

The Ride

First impressions are of the jacket’s weight, or lack of it to be precise. At less than 100g it would be a decent weight for a windproof, let alone a garment with taped seams and waterproof fabric. The gossamer-like fabric also makes it very easy to pack away in a pocket, so there is no excuse for not taking it with you, although no stow pocket or stash bag is supplied with it.

The fit of the Squall is excellent - Castelli says that it is ‘Regular’ fit, but it is pretty slim and close-fitting so it feels rather more racy than regular - the size large is perfect for me at 186cm/73kg. Despite its close fit, there is sufficient room in the shoulders and underarms to lean into an aggressive riding position, so credit to Castelli for a great cut - there is a surprising amount of stretch in the fabric, which means it can be worn over bulkier winter layers or a summer jersey just as easily.

It’s always very hard to accurately assess metrics like breathability and waterproofness as they depend so much on conditions at the time - all waterproof materials work on humidity gradients so will breathe much better when the external air is dry (such as in the Alps) rather than when it’s humid (like when it’s actually raining…). However, the Squall Shell was ‘fine’ in both departments. I know this sounds like damning with faint praise, but it isn’t meant to be, it’s a great jacket that I would happily carry and wear when necessary knowing that I will be warmer and drier with it on than without it.

That the jacket is waterproof is in no doubt; it isn’t too hard to make a waterproof fabric and all the seams are taped so any rain should be kept on the outside, whilst new at least. The DWR (durable water repellency) treatment causes the water to bead up on the outside nicely rather than wetting out the fabric (which is usually what causes any breathability issues, and which is why Shakedry was so exceptional in this regard as it had no ‘outer’ fabric), helping the jacket to breath better.

The Squall Shell material isn’t as breathable as Shakedry in my experience - some condensation built up inside when worn in more humid conditions or when working hard, but I am more than OK with that for its weight, price and how I’d use it - as a highly pocketable, waterproof/windproof layer that fits extremely well, the breathability is pretty good.

Value and conclusion

Waterproof cycling jackets are ten-a-penny, but genuinely breathable, well-fitting, packable waterproof jackets are a much rarer commodity, hence the wailing and gnashing of teeth (in my house anyway) at the demise of Shakedry. The Squall Shell jacket is not quite up to the outright performance of my beloved Gore-Tex, but it fits better, is lighter and packs down smaller. Oh, and it is less than half the price too, making it excellent value for money.

As a portable layer to don if it rains or to ward off the breeze on a chilly descent (or outside a cafe) it is hard to beat - it is pretty breathable and will keep most showers at bay quite happily. Used as such I think that it is brilliant, but don’t treat it as you would a heavier-duty jacket or expect it to keep you dry forever in monsoon conditions. For now though, the Squall Shell is my waterproof of choice.