The ornamental design for headlight for bicycles, as shown and described.
FIG. 1 is a front view of a headlight for bicycles;
FIG. 2 is a rear view of a headlight for bicycles;
FIG. 3 is a left view of a headlight for bicycles;
FIG. 4 is a right view of a headlight for bicycles;
FIG. 5 is a top view of a headlight for bicycles;
FIG. 6 is a bottom view of a headlight for bicycles; and,
FIG. 7 is a perspective view of a headlight for bicycles.
The surface shading illustrated in the drawings is provided merely to highlight the contour of design; it is not intended to be illustrative of texture or gloss.