Frame for a Bicycle

FIG. 1 is a front, left and top perspective view of a frame for a bicycle, showing our new design; FIG. 2 is a rear, right and top perspective view thereof; FIG. 3 is a front view thereof; FIG. 4 is a rear view thereof; FIG. 5 is an enlarged left side view thereof; FIG. 6 is an enlarged right side view thereof; FIG. 7 is a top plan view thereof; and, FIG. 8 is a bottom plan view thereof. The broken lines in the figures illustrate portions of the frame for a bicycle that form no part of the claimed design.