Castelli have used Gore’s latest technology to develop the new Idro waterproof jacket, said to be the lightest, most compact Gore-Tex jacket ever.

The Idro is made from the latest version of Gore-Tex Active. Whereas Gore-Tex typically has a three-layer construction, with a membrane sandwiched between an inner lining and outer textile with a Durable Water Repellent coating, Gore-Tex Active, already Gore’s lightest, most breathable fabric, now has a two-layer construction, losing the outer textile and using a ‘permanent beading surface’.

The result, Gore say, is a fabric which is wind and waterproof while maintaining breathability – and, crucially, reducing weight. Gore claim the durability of the fabric means it should retain its waterproofing after it’s been through a washing machine.

Gore have long been leaders in sports fabric technology – will this pave the way for lighter, more breathable waterproof jackets? Castelli have used the fabric to develop the Idro jacket, which has a claimed weight of 155g for a size large – needless to say, that’s very light for a jacket made from a material claimed to be completely waterproof and it will comfortably pack down into a jersey pocket. In fact, Castelli say it will fit into half a jersey pocket.

Otherwise, Castelli have taken a minimalist approach to construction, but there’s a generous amount of reflective detailing with two stripes on the rear, and a zippered opening to access jersey pockets. The jacket has a close, anatomic fit tailored for road riding.

Castelli say the Idro is aimed at the gran fondo or big mountain rider who may encounter a sudden storm in the hills and, as a result, demands a super-light jacket which takes up very little space when not being worn, but without sacrificing protection.

The Idro will be available from spring 2016 but Gore Bike Wear will also use the new fabric (as well as Gore Running Wear, and outdoor brands Arc’teryx, and The North Face)/ We expect it to be in demand from other big-name brands later in 2016.