David Glen Maxwell, 65, of Mesa, was killed Aug. 7 when his motorcycle went off an embankment east of Star Valley.
Department of Public Safety Officer William Murphy said Maxwell was riding with a group of friends when he went off on the shoulder.
"For reasons unknown, he exited off the roadway on the right," Murphy said. "He hit a delineator (an upright metal post) and that caused him to roll down a steep embankment about 30 feet into a cedar tree."
Murphy said Maxwell suffered massive internal injuries.
Maxwell was flown to Scottsdale Osborn Healthcare and died from his injuries four days later.