The ornamental design for an outerlink for a rear derailleur, as shown and described.
FIG. 1 is an outside perspective view of an outer link for a rear derailleur in accordance with my new design;
FIG. 2 is an outside elevational view of the outer link for a rear derailleur in accordance with my new design;
FIG. 3 is an inside elevational view of the outer link for a rear derailleur in accordance with my new design;
FIG. 4 is a front end elevational view of the outer link for a rear derailleur in accordance with my new design;
FIG. 5 is a rear end elevational view of the outer link for a rear derailleur in accordance with my new design;
FIG. 6 is a top plan view of the outer link for a rear derailleur in accordance with my new design; and,
FIG. 7 is a bottom plan view of the outer link for a rear derailleur in accordance with my new design.
The broken line showing of environment (the remaining structure of the rear derailleur) in the Figures is for illustrative purposes only and forms no part of the claimed design.