Castelli Idro 3 Jacket

The Castelli Idro 3 is a brilliant lightweight waterproof jacket, using Gore's top line Shakedry technology along with a series of small updates that make it one of the very best for wet weather riding.

When Castelli launched the latest iteration of its Idro jacket as we approached the end of 2021, tech editor Mat Brett covered it in a news story – we'd been suitably impressed back in 2017 when the first version came in for testing, and with a number of updates this time round, it was worth checking out exactly how Castelli proposed to improve on a jacket that had already achieved a 9/10 score.

Those updates amount to a longer cut for improved coverage, a re-jigged forearm construction, a chunkier zip for easier adjustment, and a new fabric (also from Gore) on the lower rear section that's able to stretch – one of the weaknesses of the otherwise awesome Shakedry fabric – while maintaining complete waterproofness.

These updates come together to improve the jacket marginally over its predecessors, keeping it right at the front of the pack when it comes to top-end waterproof jacket performance.

The longer cut, featuring a slightly lengthened body and collar, helps to provide comprehensive coverage that suits me with my longer-than-average body. Much like Gore's brilliant C5 1985 jacket, it is a jacket that can be left on for long periods of time, not feeling restrictive or like it might easily ride up. In heavier rain, it's a real boon to feel that 'extra' protection, while the tall collar helps to reduce unwanted draughts and leaking.

The reprofiled forearm cut is also a positive move. Where previously it might have been considered a little tight (in the typical Castelli way where a 'pro' fit naturally means small and narrow), now there's plenty of space for 'normal' sized forearms, which makes it easier to don and strip off when needed, as well as more comfortable on the move.

I'm also a fan of the gaiter fitted at the wrist. It's proven useful at keeping the elements out when the heavens have opened, and fits nicely with gloves when the temperature drops. But perhaps most importantly (for me, anyway), it makes the cuff feel so much more comfortable against the skin – in a way, it makes the Idro 3 feel more luxurious than its performance-orientated design might suggest.

On the rear, the new waterproof panel helps to deal with one of the Shakedry fabric's real weaknesses – stretchability. There isn't any stretch in Shakedry fabric (making fit and cut even more important from the off), but the new rear panel helps to deal with this, offering stretch in a key area.

Castelli says it's designed for those with full pockets, but I also think it's useful if you happen to be carrying a little extra winter weight around the gut. I certainly am, and in the size large I had on test it makes breathing that little bit easier if you happen to be working hard on a ride.

The panel is attached on three sides, with an overlap flap on the topmost edge. This allows it to stretch effectively, while offering access to your jersey pockets. There aren't any pockets on the Idro 3 itself, but there are on the Idro Pro 3 – the idea being that a pro would put it on and keep it on for the duration a training ride or race.

Castelli has also done away with the extra ventilation panels that we saw on the first generation jacket, sticking with its decision to drop them on the previous version. The fabric is so exceptional in its breathability that they're really not needed.

The YKK zip is simple to engage and disengage, and pulling it up and down with one hand while riding is easy too.

However, the downside to the new fabric panel on the rearside and the chunkier zip is that packability has taken a slight hit. Yes, roll it up and it still fits in my Rapha Brevet jersey pocket, for example, but it sticks its nose out of the top of even that relatively spacious pocket.

Essentially, at 138g in a large it remains packable enough for most riders, but if you want something that packs down really, really small, there are options that do that better, such as the Gore C5 1985 Viz.

It's also good to see reflective strips now in place and visible from the rear, boosting visibility in dark light. I don't mind a dark jacket (although a high-visibility option for Shakedry fabric would be welcome in the not-too-distant future), but this adds that little extra safety when you really need it.

I've focused a lot on the parts that have changed from previous generations of the Idro jacket, but overall, the performance remains right up with the very best. Gore's Shakedry fabric is fully waterproof and incredibly breathable (something I've been grateful for through the wet and mild Christmas period), while the quality of the seams and construction is right up there too.

You can wash it with a light detergent easily enough, but often simple rinsing it is enough if all you're trying to do is clean off some dirty road spray. The same also applies to the new fabric back panelling too.

Value

Of course, there's a price to pay. Any jacket sporting Shakedry fabric sits somewhere near the top of the waterproof price tree, but the Idro 3, at a hefty £320, looks down on most.

The Gore Race Shakedry Jacket, for example, also with stretch panels, is £299.99 (we reviewed an earlier version, the C7 Shakedry Stretch, in 2018), as is the C5 Gore-Tex Shakedry 1985 Viz Jacket, which we also reviewed in 2018.

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The only option from Gore that tops the Castelli is the C5 Gore-Tex Shakedry 1985 Insulated Jacket which, as the name suggests, has some added insulation for £329.99.

Perhaps unsurprisingly, Gore seems to offer slightly better value for similar jackets, given that it owns the main fabric technology. However, Rapha's Pro Team Lightweight Gore-Tex Jacket is still available for £220, which in the battle of premium cycling brand names (featuring Shakedry tech) is a compelling price tag versus the Idro 3.

Conclusion

Although very expensive, there are precious few jackets out there that can match the sheer performance of the Castelli Idro 3. With sensible design tweaks, it remains one of the best waterproofs out there.

Verdict

Very expensive, but if you have the budget for it, the Idro 3 is a brilliant lightweight waterproof jacket