This Castelli Squadra Stretch Vest is a modern interpretation of the wind shell vest, otherwise known as the flimsy, loose-fitting one you've kept in your pocket for a long descent or put on for the first hour of the ride until the day warms up. That vest used to be a simple affair, an essentially effective nylon shell, but the lack of stretch meant that it had to be cut on the generous side to fit all body shapes, both on and off the bike.

The design team at Castelli completely reimagined what a shell vest should be and how it's constructed. They added panels on the sides in a very high-stretch yet tightly knit fabric that gives the jacket a modern, close-to-body fit for aero gains on any terrain, and it actually keeps more heat in than a vest that's flapping about. It was kept very compact so that it can pack away into minimal space in a jersey pocket. The stretch panels are treated for water repellency, which will help in a light mist, but this is a vest so other protection in the form of arm warmers may be needed for some conditions. The comfortable collar is tall to keep cool air out, and Castelli adds reflective details on the chest and lower back for low-light visibility.