The photo below is my rendition of what Ann Forrest might look like riding a motorcycle:

Scene 325 of The Grim Game takes place on a mountain road where we see Mary (Ann Forrest) riding in on a motorcycle.  After riding a long distance, the road is too rough for Mary to go any farther.  She stops and gets off of the motorcycle and proceeds quickly up a path. [Paraphrased from files at Margaret Herrick Library]