Abstract: A collapsible helmet for cyclists, the collapsible helmet comprising: at least one elongate, curved central portion adapted to extend over a crown of a user's head from front to back; and, a plurality of side portions supported either side of the at least one central portion, the plurality of side portions configured to nest substantially under the at least one central portion when in a collapsed position, and the plurality of side portions configured to form a helmet when in an operative position; and, at least one flexible strap interconnecting the plurality of side portions and the at least one central portion, wherein the at least one flexible strap limits the relative separation of the plurality of side portions in the operative position.