The crash happened at 2.40pm (27 February 2020) when the rider was struck by a white truck on Abecrombie Street at Ultimo.
The truck failed to stop after the collision.
The motorcyclist was pronounced dead at hospital.
UPDATE: Police have now arrested a man near the scene at 4.50pm today and taken him to a hospital for mandatory testing. A truck has been seized for scientific examination.
There are no further details available at this time.
Policer are appealing to anyone who might have been in the area at the time of the collision, particularly anyone who may have captured dash-cam footage is urged to contact Crime Stoppers: 1800 333 000 or https://nsw.crimestoppers.com.au
It follows a tragic five days on the roads for riders:
On Tuesday, a 53-year-old male rider died in a tragic twist of fate involving two other vehicles on the New England Highway, south of Toowoomba, Queensland. Police say a utility was waiting to turn right into Opportunity Drive at Clifton when it was struck from behind by a station wagon. The utility was propelled into the path of the rider heading north on the highway. He died at the scene.