The ornamental design for a brakedisc for motorcycles, as shown and described.
FIG. 1 is a front elevational view of brake disc for motorcycles according to an embodiment of my design; the rear elevational view being a mirror image of that shown;
FIG. 2 is a left side elevational view thereof; the right side elevational view being a mirror image of that shown; and,
FIG. 3 is a top plan view thereof; the bottom plan view being a mirror image of that shown.
The broken lines are for illustrative purposes only and form no part of the claimed design.