It's that time of year when the weather becomes a lot more changeable and even on sunny days, the skies can darken and drench you without much warning. Wind shells aren’t much help in those conditions, and most fully waterproof jackets are too bulky to pack in a jersey pocket.

Gore Apparel’s revolutionary One GTX Active Shell solves those problems. The secret sauce? Gore-Tex managed to make the waterproof-breathable membrane that is the heart of all waterproof shells into its own outer layer, eliminating the need for an outer fabric. That makes the One GTX Active far lighter than conventional rain shells (our size small tester is 102 grams) and easy to pack in a jersey pocket with even a little room to spare.

What’s more, the simple construction actually makes it work better. Outer fabrics eventually get wet, which harms breathability when the warm water vapour you’re producing gets trapped inside. But the permanent beading surface on the One GTX Active never gets saturated; you can dry it off with literally a shake of an arm. So even as you stay dry from the outside, you won’t get soaked with sweat.

The One GTX Active has a snug fit (so be generous if you’re in between sizes), and has just a single zippered pocket in front. The high collar seals out drafts and wind-driven rain, and the long tail keeps spray off your back. The One GTX Active has gotten us through sudden cloudbursts that drop an inch of rain in 30 minutes; long, drizzly spring road rides; and even works as a windproof layer on cold, dry days.

How to layer your bike clothes for every temperature (video courtesy of our American sister title Bicycling):

The Gore One GTX Active has an Australian RRP of $433, but can usually be found for around $100 less. Be aware that this jacket is intended for road riding only - mountain bike pack straps will abrade the membrane.