The ornamental design for a bicycleseatstay, as shown and described.
FIG. 1 is a right, rear, top perspective view of a bicycle seat stay with a remainder of a bike frame shown in broken lines;
FIG. 2 is a front elevation view of the bicycle seat stay of FIG. 1 with a remainder of a bike frame shown in broken lines;
FIG. 3 is a rear elevation view of the bicycle seat stay of FIG. 1 with a remainder of a bike frame shown in broken lines;
FIG. 4 is a right side elevation view of the bicycle seat stay of FIG. 1 with a remainder of a bike frame shown in broken lines, the left side elevation being a mirror image thereof;
FIG. 5 is a top plan view of the bicycle seat stay of FIG. 1 with a remainder of a bike frame shown in broken lines; and,
FIG. 6 is a bottom plan view of the bicycle seat stay of FIG. 1 with a remainder of a bike frame shown in broken lines.
The broken lines showing portions of the design in all figures is included for the purpose of illustrating environment and unclaimed features and forms not part of the claimed design.