Abstract: A method for adjusting the comfort level of a helmet includes the steps of acquiring head shape data by measuring a three-dimensional shape of a head of a wearer of a helmet, inputting inner surface shape data showing a three-dimensional shape of a helmet inner surface, acquiring space information showing a space between the head and the helmet inner surface on the basis of the head shape data and the inner surface shape data, and displaying additional images showing the space information on a display part by superimposing the additional images on i) a shape image showing the inner surface shape data or ii) the shape image showing the head shape data and the inner surface shape data.

Abstract: A chin guard support mechanism includes first and second fixed-side members, and a moving-side member fixed to the chin guard. When the chin guard pivots forward from a down position in a rising direction, an annular following surface provided on the moving-side member pivots forward while following an annular followed surface provided on the second fixed-side member to make the chin guard rise while moving forward. It is possible to provide a helmet that allows the chin guard support mechanism capable of relatively excellently raising/lowering the chin guard to have a simple structure, allows to operate the chin guard support mechanism smoothly, obviates the necessity of making the structure in a region including an end of the chin guard including the chin guard support mechanism and a vicinity thereof bulky, and obviates the necessity of making the widthwise size of the helmet large.

Abstract: A shield includes one or more protrusion members having shapes protruding from an outer surface of the shield are provided or, alternatively, one or more recesses having shapes depressed from the outer surface of the shield are carved. The one or more protrusion members or the one or more recesses are located at vicinities of both side positions on the shield for covering a face where the lateral width of the shield in right and left directions becomes a maximum.

Abstract: A helmet includes the first pad in contact with an occipital region of a rider, and each of the second pads in contact with the cheeks of the rider. Since the first pad moves from the first occipital region-contact position to the second occipital region-contact position as well as the second pad moves from the first cheek-contact position to the second cheek-contact position, the helmet is moved relative to the rider's head by a predetermined distance.

Abstract: An aerodynamic control device includes a void opening. The void opening decreases a resistance of a turbulence generated by a component part located behind a center of a longitudinal width of a helmet and is formed so that one end is connected to the helmet and the other end protrudes backward from the helmet.