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Gore's C5 Shakedry jacket uses an ultraminimalist version of the Gore-Tex waterproof material to produce a very lightweight, hugely breathable jacket that still offers real foul-weather performance. The athletic cut is best suited to drop bar bike use and being both fragile and expensive, it's not for anyone that regularly parts company with their bike.

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The concept behind the Gore's Shakedry jackets is that, instead of the usual three-layer construction of a breathable membrane waterproof, this just uses a waterproof, breathable membrane and an inner liner without having the tough outer layer. That means breathability is improved at the expense of durability and - this is where the name comes from - it requires no additional Durable Water Repellent coating to help water bead off it, helping to prevent it from 'wetting out'.

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The C5 is mostly aimed at road cyclists, so it's got a pretty athletic cut that fits best when you're in a drop bar riding position, thanks to decently long arms and a low dropped back. I've got relatively broad shoulders for my height and found that, while not hugely uncomfortable on a mountain bike, it definitely started to get a bit tight under the pits when riding 780mm-odd wide flat bars.

The hem is elasticated and stays in place well

We've also had the R7 Shakedry on test - technically a running jacket - that uses the same material with a hood and it doesn't suffer from this issue thanks to a slightly more spacious cut around the armpit, so this is probably the one if you think this will be an issue for you too.

The wrists are non adjustable, but a stretch panel keeps them snug

Either way, the cut is bang on when you're on the drops or tops of a gravel machine, with the elasticated waist staying in place effectively. Apart from the front waterproof zipper and velcro neck adjustment, it's absolutely minimalist with just a single zippered pocket on the back of the jacket and nothing on the front.

There's a single zippered rear pocket that the jacket packs into

It's worth noting that Gore says you shouldn't use a backpack with this material, which goes to show their concerns about durability. While I've no doubt it'd suffer badly in a crash, it's proved to be surprisingly tough given the feel of the material, with a few scrapes down the odd tree trunk not tearing the material. That said, if you regularly part ways with your bike, it's simply far too expensive a jacket to risk it.

However, in terms of breathability, this is simply the best jacket I've ever used, staying comfortable and unclammy even in reasonably warm but wet weather. The fact that the fabric is so light adds to the lack of claustrophobic feeling that usually has me suffering the sogginess of exposing myself to the weather rather than boiling to death in a normal waterproof. It's also weathertight in really heavy rain and wind, which was a surprise considering the thin fabric.

A long drop back works well for when you're stooped over

Water really does bead off it amazingly well too. As with all waterproof membrane jackets, keeping it clean is key to the best performance and this is easily achieved with regular liquid detergent, though at this sort of money, it probably makes sense to treat it to a specific wash. I deliberately left it a bit grubby with dirt for a few rides and didn't notice any significant deterioration of the breathable qualities, however, I wouldn't be risking grit degrading the material if it was my own money. That said, the quality of construction is second to none and it's put up with less than gentle handling and washing very well.

All in all, this is one of the best year-round waterproof jackets I've ever used - the best when it comes to breathability - and if you can live with the drop-bar cut, massive price tag and less durable fabric versus a traditional jacket, it comes highly recommended.

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