For a weatherproof cycling cap, it doesn't much lighter than the C5 Gore-Tex Shakedry Cap. Stash one away in your jersey pocket or a saddle bag in case Mother Nature decides to open the skies and drench you halfway through the ride. Of course, you can don the cap right from the start if you anticipate cold winds or rain, at a mere 22g you might barely notice it's there. The cap fits nicely under your helmet, using an elastic back to provide a secure and universal fit. The Gore-Tex Shakedry material is both waterproof and windproof, keeping your head warm and dry in variable poor weather. Should you start to heat up during a tough climb, Shakedry is also breathable, letting that warm air escape so you don't overheat. As alluded to above, Shakedry is the lightest version of Gore-Tex, consisting only of a membrane bound to a nylon shell, foregoing the outer fabric that tends get saturated and "wet out" in heavier rain anyway.