Castelli Squall Shell Jacket

The Castelli Squall Shell Jacket is a breathable, water-resistant, windproof and super-light jacket. It has a racy, tight fit that works well in spring and autumn – and it packs down so small that you might as well take it on every ride.

Expensive

Castelli’s Squall Shell Jacket is very similar to the Sportful Aqua Light that my mate Jez reviewed, so we’ve been comparing notes during the review period.

Both are made from the same stretchy, almost see-through, lightweight two-layer fabric with a waterproof membrane. Both pack down incredibly small and weigh almost the same – 85g for the medium Castelli, 93g for the Sportful.

Both jackets are ideally suited for rides with changeable temperature conditions: climb up an Alpine pass, wear the jacket for the descent; or start early doors and wear it until it warms up a bit.

One major way in which the jackets differ is in how they are marketed. Sportful claims a ‘reliable protection with an awesome waterproof rating’ for its jacket, suggesting it is a fully featured waterproof. Castelli describes the Squall as ‘designed to keep you dry in case of a shower or to take the chill off when you descend from the mountains’, giving it an expectation of it being showerproof rather than waterproof.

Castelli does confuse matters somewhat by giving the Squall a 5/5 waterproof rating, but for this review, I’m judging Castelli’s Squall against the description, not the rating. For reference, the Sportful didn’t score that well because of Sportful’s claims about the waterproofing.

Waterproof?

The jacket’s taped seams hint at a waterproof status, but the one-way zip is, at best, water-resistant.

In use, after an hour of sustained rain on a low double-digit temperature ride, it was obvious from the discolouration of the jersey I was wearing under it that my chest and stomach area were wet, as well as the tops of my arms and shoulders. I’m putting that down to water getting through the zip and the fabric wetting out, respectively.

The only dry areas were my armpits.

I don’t have a reliable way to tell the difference between rain and sweat, but I’m going to say that the above suggests that it was rain getting through rather than sweat building up, which was the cause of the jersey underneath getting wet.

A heavier waterproof, in my experience, would have kept me drier.

Breathable

One advantage of the jacket’s lightweight fabric is that it dries very quickly. And it’s pretty breathable too, more breathable than the weightier waterproofs I’ve tried.

This means that, as long as it’s not too cold, it doesn’t matter that much if you get a bit wet in changeable weather, because as soon as the rain stops, you’ll dry out pretty quickly.

In dry weather, where I was wearing the jacket to keep me warm and/or to keep the wind off, I found the Squall good at keeping on top of sweat evaporation. I didn’t find myself in a hurry to take the jacket off as I would if I was wearing a ‘proper’ waterproof jacket, and when I did there was less sweat than I expected.

Durability

That’s just as well because the fit is tight. The stretchy fabric really helps here, resulting in a fit resembling that of a jersey. The jacket’s rubberised finish inside means there’s a bit of friction, especially when you’re trying to get your arms out of the sleeves. And when the fabric is wet, it becomes worse still.

I’d strongly suggest not rushing when you’re putting this on or taking it off, as the flipside of the jacket weighing so little and packing down so small, is that the fabric feels fragile. I didn’t rip the fabric during testing, but I reckon it would be easy to do in a fit of impatience.

A couple of little holes have developed where I’ve snagged the jacket on the zip of my frame bag, while putting the jacket away. So if you want it to last, take care.

Temperature

Castelli gives a 4-18°C temperature rating, though personally I think that would depend on factors such as the wind and rain and what you’re wearing beneath it.

Having used this jacket a few months, I’d wear it as a waterproof above 10°C – and I’ve actually worn it in the sort of conditions that would defeat any waterproof. It was mid-teens warm on that ride, and it doesn’t really matter how wet you get, whether from rain or sweat, as long as you’re wearing something that keeps the worst of the wind off and stops you from getting cold. The Squall was fine for that and I only got cold at a food stop, warmed up again when we got going.

My experience suggests I wouldn’t get away with that below 10°C or so, and in those conditions I wouldn’t set off wearing the Squall.

If it’s dry, the Squall will work to keep you warm in much lower temperatures, down to about the claimed 4°C by keeping the wind out and the warmth your body generates in.

Sizing

Castelli’s size chart suggests I’m a medium in the chest and large in the waist. Our medium was a good fit, or at least in spring through to autumn, but in spite of what Castelli claims, I don’t think the fabric is stretchy enough to accommodate a jacket underneath it without sizing up.

For me, the fit is one of the jacket’s stand-out features and I think in winter you’d want a more substantial waterproof anyway, so I wouldn’t consider sizing up.

Features

This jacket is available in black, white (bad idea much?!), and the ‘electric lime’ on test.

This is a minimalist jacket. No stuff sack, no hanging loop, no pockets – all of which would add weight, of course. There’s a small amount of fabric in the chin area to stop the zip eating your beard, but no storm flap. The back is dropped to some extent, but not enough to keep your rear end dry without mudguards.

There is a decent sized reflective stripe on the back and the arm logos are reflective. But while I think the visibility is good enough for commuting, I’m not sure the fabric would be tough enough for heavy day-to-day use.

Value

The Castelli Squall Shell Jacket costs £130, which is £40 more than the Sportful, which talking to Jeff I think has a similar level of water resistance. The Sportful gets a two-way zip, Castelli offers more colours. I can’t really say what justifies the big price difference.

It’s quite hard to compare the Squall with other jackets, as it’s more waterproof than your typical windproof – but lighter than a typical waterproof.

The Galibier Tourmalet jacket is genuinely waterproof but doesn’t pack down nearly as small.

The 7mesh Mission Jacket is a good option if you’re after a lightweight waterproof, but it costs £300, doesn’t pack down as small and the fit isn’t as good.

And while we haven’t tested it, the Van Rysel Long-Sleeved Road Cycling Rain Jacket Racer Ultralight looks like it’ll be a decent shower-proof top and it costs just £39.99.

For further options, check out our best cycling jackets and best windproof cycling jackets buyer’s guides.

Conclusion

As a pack it just-in-case windproof Castelli’s Squall jacket is excellent. It’s light, it packs down extremely small and it fits really well. It’s also water resistant and dries quickly, and its breathability is better than I expected. But it’s not a full-on waterproof and it’s also a fair bit more expensive than what I consider to be its nearest competitor.

Verdict

Super-light packable and breathable windproof with a great fit that will keep you dry in showers

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