Dwight Beare, 27, from Melbourne, Australia, was killed in the crash near to the 16th milestone on the TT course on the Isle of Man.
Mr Beare suffered fatal spine and back injuries on the west of the island on 4 June at about 14:10 BST.
A verdict of misadventure was recorded by Coroner John Needham at Douglas Court House earlier.
Mr Needham said: "I am not in a position to give an exact reason for the loss of control but Mr Beare would have died almost instantaneously".
The inquest heard from a witness who said the carpenter and his passenger, Benjamin Binns, were thrown into the air after their vehicle hit the road side.
Mr Binns, who was airlifted to hospital with a broken leg, said before the race both he and Mr Beare had been "excited and confident".
"I will miss my friend dearly and his memory will live on," he said.
No defects were found on the vehicle.
Mr Beare moved to Onchan on the Isle of Man to pursue his road racing passion.
He made his TT debut in 2014 finishing 12th in the second race of the week, with his father Noel as his passenger.
He returned in 2015 when he came 17th.
A TT racer died after being thrown from his sidecar when he hit the side of a road, an inquest has heard.