FIG. 1 is a rear perspective view of a back support for a wheelchair showing our new design, the broken lines are for illustrative purposes only and form no part of the claimed design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a side elevational view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof.