Police believe Jenni McLennan (36) was riding her Harley-Davidson on the Australind Bypass when she crashed and was then hit by a 4WD on Monday.
The female 4WD driver stopped briefly and then drove off, failing to return to the scene.
Liz McLennan said police knocked on the door of her Dunedin home just after 11pm. She was told her daughter was in hospital with ''serious head injuries'' following the hit and run.
Fortuitously, Mrs McLennan received a phone call from Jenni at the same time, and despite ''not sounding too flash'' she was able to reassure her worried family before going into surgery.
''She can't remember anything of the accident, afterwards or even the start of being in hospital.''
Mrs McLennan said her daughter was a cautious motorcyclist, who had only come off a bike a couple of times because she was going too slowly.
Her daughter, who was now missing a chunk off her knee, realised ''she was very, very lucky''.
Jenni, who works as a second mate on supply ships to oil and gas platforms, was in Dunedin last week and still had several weeks of leave to recuperate.
''She is hoping she can get back to work,'' Mrs McLennan said.
Her Harley-Davidson was written off, and while insurance was likely to cover a new Harley, her mother was ''not very impressed''.
Mrs McLennan praised Dunedin police who contacted the family and hoped their counterparts in Western Australia found the driver.
Western Australian police media spokesman Samuel Dinnison told the Otago Daily Times yesterday police were trying to obtain a vehicle description from witnesses.
