Brimbank Highway Patrol are calling for witnesses following an alleged road rage incident in Sydenham in July.
A silver BMW sedan intentionally reversed into a motorcycle on Silverdale Crescent around 2.45pm on July 23, police say.
As the rider got to his feet he was approached and threatened by the male driver of the BMW.
The driver then ran back to his car and began rummaging around.
Believing him to be armed the rider of the red Ducati fled on foot.
The man then attempted to steal the motorbike before leaving with a woman in the BMW 318i, which had no registration plates and possibly a defect notice attached to the window.
The driver is described as being about 23-years-old, 175cm tall, with a strong build, full lips and a receding hairline.
The woman is described as having shoulder length brown hair, decaying teeth and a number of piercings in her left ear.
Police have released CCTV vision and FACE images the pair.
