Castelli has introduced a new version of its Idro waterproof jacket, still made from Gore-Tex ShakeDry fabric but with new features designed to improve the performance.
“Our goal is for the Idro 3 to be that jacket that’s extremely small in your pocket so you can always carry it with you, but that will remain very functional when you need it,” says Castelli. “We made it longer for rain protection, gave it a bigger YKK zipper that’s easier to start and to adjust on the fly, we covered more of the neck, and we included a stretch panel on the lower back that stretches overstuffed pockets while avoiding extra flapping material when used over empty pockets.”
If you don’t know about Gore-Tex ShakeDry, where have you been? Essentially, Gore puts the membrane on the outside instead of sandwiching it between two textile layers. Rain hits the PTFE membrane, beads up, rolls off… Job done! In our experience, ShakeDry works well and several brands have used it over the past few years.
The fabric is thin and lightweight – just 49g per square metre – and has a 28-metre water column waterproof rating. It’s also extremely breathable so you don’t need to take it off as soon as the rain stops.
On the flip side, the lack of an outer layer means ShakeDry isn’t as durable as some heavier fabrics, there’s no stretch, and it’s only available in dark grey/black.
Castelli says it has taken all of this into account with its new design.
“The new lower sleeve construction on the Idro 3 features a wider forearm, but there’s an inner stretch gaiter that seals against the wrist while the outer layer extends right to your hand,” says Castelli. “This system makes the jacket easy to put on and take off, and when you use the jacket in the rain you can pull your glove over the jacket’s wrist gaiter, and then pull the jacket sleeve over the glove to completely seal out the rain.
“Aside from the wrists, the most notable update is in the large stretch panel on the lower back. This stretchy panel allows us to cut the jacket to fit close-to-body for the skinny climbers among us, yet also expand for cyclists with more girth, whether that comes from full pockets in the back or a few extra kilos on the front.”
This stretch panel is made from a Gore-Tex fabric snappily called SST40WK T1 2L. Gore describes it as a “revolutionary low force to stretch, highly elastic laminate”. It’s said to be waterproof and when Liam reviewed Gore's own ShakeDry Stretch jacket, he found it to work very well indeed.
“This stretchy panel is meant to be in tension (stretched) during normal use on all but the skinniest cyclists, so that meant it had to be cut smaller than the panel on the centre back, which in turn meant the two panels of differing lengths couldn’t be stitched,” says Castelli. “We simply overlapped them so water wouldn’t come in while also providing a bit of ventilation to help the breathability of the fabric.”
The Idro 3 features full-length reflective tape on the outside of each sleeve and more reflective trim on the lower back.
The neck is cut high and Castelli has removed elastic from the waist, instead relying on that stretch panel on the back. The neck, waist and wrist gaiters are welded rather than stitched. Castelli says that the body and arms are cut long to provide good coverage.
The Idro 3 is available in both men’s (£320) and women’s (£300) cuts. The cuts are different, obviously, but the features are identical.
“There’s also the Idro Pro 3 Jacket,” says Castelli. “We call it Pro because it’s really designed as workwear for the pros. If your job means riding all day in the wet, and you need a jacket that trades storability for extra riding features, then maybe the Pro version is for you. It has more stretch panels for an even more comfortable fit, a longer tail, and two external pockets, but when you stow it away it’s going to fill your middle pocket.”
Castelli claims a weight of 136g for the men’s jacket in a medium-size, 120g for the women’s version in a small-size, and 178g for the Idro Pro 3 in a medium-size.
Mat has been in cycling media since 1996, on titles including BikeRadar, Total Bike, Total Mountain Bike, What Mountain Bike and Mountain Biking UK, and he has been editor of 220 Triathlon and Cycling Plus. Mat has been road.cc technical editor for over a decade, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a Cambridge graduate who did a post-grad in magazine journalism, and he is a winner of the Cycling Media Award for Specialist Online Writer. Now over 50, he's riding road and gravel bikes most days for fun and fitness rather than training for competitions.