The 38-year-old Para-cyclist caught compatriot Crystal Lane, who took silver, after only 1,375 metres of the C5 3,000m individual pursuit final.
Dr Gary Brickley, Senior Lecturer and exercise physiologist, has been coaching Sarah since 2004 and was in the arena to watch her winning race.
He said: “It was another brilliant performance by Sarah. I knew she was in great shape. Breaking the world record in the morning heats proved how well she had prepared and trained for the Paralympics.
“In the final it appeared to be a relatively easy win but that is only a product of hard work in training.