Police were called to reports a car had collided with a motorbike in Talgarth Road; the driver did not wait for officers to arrive.
The biker, 59 year old Martin Wall, was taken to hospital suffering a broken collar bone.
He was discharged but became unwell and died on New Year’s Day.
Officers are appealing for the man who was driving what is believed to be a BMW, to come forward and speak to them.