A Victorian judge has broken down in court, telling the family of a motorcyclist dragged under a stolen BMW and killed that there was nothing the court could do or say to bring the victim back.

The County Court Judge sentenced an 18-year-old man, who was 17 at the time of the crime, to a minimum four years in jail, with a maximum of six.

Keith Stevens, pictured here with his partner Amanda Wilson, died after he was knocked off his motorcycle.

The courtroom erupted soon after the sentence was handed down, with the girlfriend of the victim sobbing before a heated exchange between her family and the family of the teenage driver.

Keith Stevens was knocked off his motorcycle when the teenager, driving a stolen BMW with three friends, failed to give way at an intersection in a residential street in Mitcham on November 8, 2017.