Police said there were "overwhelmed" by the reduction in casualties this year, down from 26 last year to just eight this year.
Inspect Mark Britton of the Roads Policing Unit. "Injuries were to a German motorcycle rider who crashed as Signpost Corner, breaking his leg, and the other was a broken ankle to a rider after a crash at Guthrie's."
The other accidents resulted in damage to vehicles, but not drivers or riders.
Inspector Britton said the presence of police officers around the course with speed guns made a significant difference to discourage reckless driving.
"I am overwhelmed that we did not have any significant collisions on Sunday. It shows that people are heeding the road safety message, although there was still some unacceptable rider behaviour."
He also paid tribute to police officers for helping to keep the roads safe but also issued a warning to riders and drivers : "Although Sunday was quiet we won't be complacent about the rest of the week."
