The ornamental design for a bikerack, as shown and described.
FIG. 1 is a front view of a bike rack showing my new design as it would appear with a bicycle attached;
FIG. 2 is a back view thereof;
FIG. 3 is a right-side view thereof;
FIG. 4 is a front view thereof;
FIG. 5 is a top view thereof;
FIG. 6 is a bottom view thereof;
FIG. 7 is a left-side view thereof; and,
FIG. 8 is a front view showing the bicycle-holding section fully extended, and also shown broken away at the bottom left edge for convenience of illustration.
The dashed lines used in the figures are environmental and form no part of the claimed design.