Kimmage had a career as a professional cyclist, participating in three Tour de France races and riding for teams RMO and Fagor-MBK. He retired in 1989 with no wins, blaming systemic doping in the peloton. In his book Rough Ride he detailed his experiences as a domestique which included references to drug use, including his own. Kimmage maintains a passion for the removal of doping from the sport of cycling.