As of tomorrow morning, The Great Race is back — almost before anyone realized it was gone. “The world’s oldest triathlon,” as founder Eppie Johnson, the late restaurateur and master spieler boldly dubbed it, is being held once again on a nearly 25-mile course along the American River. It has a new name — Great American Triathlon — but still consists of participants running almost 6 miles, then bicycling 12-and-a-half miles and, finally, paddling a little more than 6 miles.