Castelli builds added visibility into its Idro 3 packable waterproof jacket

The new Idro 3 is a lot like the Idro 2, with improvements in breathability, waterpoofing and weight - as well as reflective strips

Castelli Idro 3 on the ride
(Image credit: Future)

Castelli has introduced a revamped version of its Idro jacket, with claimed improvements across breathability, waterproofing and packability (weight). 

More notably, however, the Italian brand has added in some visibility aids, to counter the fact that the legendary Gore-Tex Shakedry fabric cannot be dyed.

The Editor's Choice winning Idro takes its name from the Italian for hydro, and this is a packable suited to wet weather. However, since changing conditions - especially if you're lucky enough to spend some time in the mountains - mean rainy rides might start or end in sunshine, breathability and packability are as important as waterproofing when it comes to creating the best waterproof jackets for cycling.

To achieve its goals, the Idro uses Gore-Tex's famously good Shakedry fabric, this places the membrane on the outside as opposed to between two textile layers. Water splashes directly onto the PTFE membrane, and 'shakes off', allowing for a lighter and more effective overall construction.

The inner textile uses a microfiber nylon 6.6 woven material, which is thin but resistant to tears.

To pass ISO 6630 waterproofing durability tests, this jacket can withstand 500 hours of 'continuous agitation', which is pretty impressive in our book.

Castelli Idro 3 range
Idro 3 men'sIdro 3 women's Idro Pro 3
Weight136g (M)120g (S)175g (M)
Temp range4°-18°C4°-18°C4°-18°C
SizesS-3XLXS-XLS-3XL
RRP£320£300£360

The drawback of Shakedray fabric is that it can't be dyed, so, it's not the most visible. Other brands utilising its properties, such as Rapha, have opted to interrupt the material with additional visibility aids.

The new Idro 3 now comes with reflective strips on the outside of both sleeves, as well as one at the lower back, and the brand has added in a reflective trim.

Those who prefer to opt for bright colours to aid daytime visibility still might feel this dark colour isn't a practical choice for riding in overcast conditions, here, Castelli's shrug is almost audible from the page: "hopefully you’re riding with a flashing light in all conditions and not relying just on your clothing to be seen."

Castelli Idro 3

(Image credit: Future)

Other updates include wider forearms, following some criticism of the Idro 2 for being a little hard to pull on and off.

There's also a stretch panel at the lower back, to help create a jacket that fits perfectly for "skinny climbers" as well as, well, average or above-average sized climbers. This will also help out on those days where you've got loaded pockets in anticipation of a big day out.

The range includes an Idro 3 men's (£320), Idro 3 women's (£300) and Idro Pro 3 jacket (£360). The latter is "really designed as workwear for pros", and comes with more stretch panels, a longer tail, and two external pockets. This means it's larger, so will fill your middle pocket if you need to stow it.

Michelle Arthurs-Brennan
Michelle Arthurs-Brennan

Cycling Weekly's Tech Editor Michelle Arthurs-Brennan is a traditional journalist by trade, having begun her career working for a local newspaper before spending a few years at Evans Cycles, then combining the two with a career in cycling journalism.


When not typing or testing, Michelle is a road racer who also enjoys track riding and the occasional time trial, though dabbles in off-road riding too (either on a mountain bike, or a 'gravel bike'). She is passionate about supporting grassroots women's racing and founded the women's road race team 1904rt.


Favourite bikes include a custom carbon Werking road bike as well as the Specialized Tarmac SL6. 


Height: 166cm

Weight: 56kg