Senior Sergeant Anthony Bond, of Dunedin, said the man was struck while heading south on Pine Hill Rd (State Highway 1) and crossing an intersection with Great King St North at 3.50pm yesterday.
A 40-year-old woman failed to see the cyclist, Snr Sgt Bond said.
The man was taken to Dunedin Hospital and potentially has suffered a serious neck injury.
Snr Sgt Bond said there had been a lot of crashes at this intersection over the years, and a few trucks with failed brakes had ended up in the city's Botanic Garden.