The ornamental design for a bicycle, as shown and described.
FIG. 1 is a perspective view of a bicycle;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a right view thereof;
FIG. 5 is a left view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a perspective view thereof, showing an attached basket.
The broken line showing wheels in FIG. 1-FIG. 7 and a basket in FIG. 8 is included for the purpose of illustrating environmental structure and forms no part of the claimed design.