On rides when we need a little bit more protection, we throw on the Castelli Fly Vest and then basically forget it's even there. The vest is so light that we can be forgiven for almost forgetting about it, and the only reason we remember it's there is because of all the protection it offers. Light insulation offers a little extra heat retention, but it really shines on windy days as we put our heads down and cut through the wind like an arrow. With three deep back pockets, we can bring plenty of hydration and some snacks to break through the bunk, and the zippered security pocket keeps our phone and keys close while we push ourselves to the finish line.