Joe Nikrent & Fred Horey

Driving for the Case team, probably in 1913, is Joe Nikrent. With him is Fred Horey, who was his riding mechanic at the Indianapolis 500 in 1913. Their Case racer placed eighteenth, lasting only 67 laps. Nikrent was born in Detroit but moved to Los Angeles. Perhaps his biggest victory came when he won the 1909 Phoenix to Los Angeles off-road race across the desert. This race is also known as the "Cactus Derby." Horey also was a driver, but never in the Indianapolis 500. He was the International Motor Contest Association (IMCA) champion in 1925.
 
For a great reference for identifying riding mechanics of the Indianapolis 500, check out John Blazier and Tom Rollings' book, "The Riding Mechanics" at Chuck's Toyland.