Rimfire is Modo's teenage nephew where the boy idolizes his famous freedom fighting uncle. He was 19 during his debut, although we later see him at 16 and even younger.
In Break Up, Rimfire was briefly selected as Throttle's replacement when Throttle is promoted to one-star general and to be reassigned to Mars. However, Carbine decided to rescind Throttle's promotion after seeing that Rimfire still wasn't up to spec as a "Biker Mice," even after a year's training.
Having been taught manners by both his grandmother and his uncle, Rimfire is a perfect gentleman, using both "Miss" and "Ma'am" in woman's names (i.e., "Miss Charley Ma'am") In almost every episode he's appeared in, he gets captured.
Rimfire has cream-colored fur and brown hair with an orange/blonde stripe down the middle. In the 2006 series, he has brown fur and the same orange streak through his hair.