Most cycling caps weren't designed to be worn under a helmet—they evolved from casual wear and got adopted by riders who wanted sun protection or a way to manage sweat. The Peloton Cap from Giro starts from the opposite direction, built specifically for under-helmet use with a shortened brim that preserves your upper peripheral vision when riding in the drops. You can actually see where you're going without tilting your head up to peek under the brim.

The 50% Nanobon, 50% polyester construction uses bamboo charcoal fibers that naturally resist odor buildup—useful for a piece that lives inside your helmet and absorbs hours of sweat. The fabric is thin enough to fit under a helmet without creating bulk or pressure points, and Giro's Smart Seam construction reduces the raised edges that can dig into your scalp over long rides. The cap essentially disappears once your helmet goes on.

Beyond managing sweat, the cap adds a layer of warmth for cool morning starts and shoulder season riding. The brim shields your eyes from low-angle sun and light rain. It's also a practical solution for bad hair days—throw it on for the coffee stop without revealing what your helmet has done to your hair. The one-size design uses stretch in the fabric to accommodate a range of head shapes, and the thin material means it won't affect your helmet fit or ventilation.