Adams, 59, left Monday's track practice on his bike and was waving goodbye to a student when he crashed into the thick metal arm of a parking-lot barrier. Adams died at the hospital after two surgeries were unable to save him from severe internal injuries.
David Adams, Marion's brother, said that he had been resuscitated twice, but doctors couldn't stop the bleeding.
"Doctors told us that most people would die right away from an injury like that," David said. "But Marion was a fighter, and they twice resuscitated him. They opened his chest to massage his heart, and thought he had a chance. But they could never stop the bleeding. It was too much."
Adams, a former Rio Linda High School student, had returned to coach and teach at his alma mater.
"Marion was the most popular and nicest man on campus; just a great guy," said Rio Linda's athletic director and football coach. "It's a huge loss, devastating to our community."
Adams is survived by his wife, Kathy, two children and two grand-children.
“He was a great dad, always wanted me to do my best, tried to help everybody he could,” his son Joe told CBS Sacramento.