David Stevens, 25, was riding his off-road motorbike along Bowhill Rd, North New Brighton, to a friend's house he crashed after getting the speed wobbles.
Inspector Al Stewart said David Stevens was travelling between 80 to 90kmh in the 50kmh area and his helmet was not done up. It came off when he hit the road.
Mr Stevens said his son had suffered extensive brain injuries and died at 1pm Monday, after his life support was turned off.
"Turning his life support off was one of the hardest decisions myself and my wife, Marion, has ever had to make. We kept telling him to come back and to stop mucking around. We spent every night with him and only came home to shower. The doctors tried to get him to respond to them but nothing happened. We knew he wasn't coming back. He showed no signs of recovery. He was clinically brain dead. We were devastated. We thought we had a bit more time with him," he said.
Mr Stevens said he had offered to drop his son off at his friend's house.
"I offered to drop him off but he said 'don't worry about it dad, I'll just take my bike. It's only up the road.' I told him to be bloody careful and to wear his helmet.
"Jamie (the friend) turned up at our house and said he'd been trying to get hold of David but he wasn't answering his cell phone. I tried to ring his cell phone and that's when the nurse answered. We had no idea what had happened," he said.
With tears streaming down Mr Stevens' face, he drove with his wife, Marion and Jamie from his Bower Ave home around the corner to the accident site on Bowhill Rd.
"The police officer told me to get to the hospital. He said it's very bad. I hoped it wasn't too serious. The doctors told us to prepare for the worst as soon as we arrived at the hospital. He had a fractured wrist and other grazes.
"Friends and family got a chance to say goodbye. We are coping okay considering but it's very hard. The support we've had has been overwhelming," he said.
David's partner, Karina, brought their three month-old-daughter, Aleigha, up to the ward and lay her in his arms.
"David was over the moon when she was born. It was one of the most proudest moments of his life," he said.