In the latest incident, emergency services were called to South West Rocks on the NSW mid north coast on Sunday afternoon.
They found a rider had crashed on the road before becoming trapped under a nearby vehicle.
Emergency crews worked to free him before he was treated by paramedics for critical injuries, however, he died at the scene.
Earlier, in far-north Queensland, a 31-year-old man lost control of his quad bike on a local road at East Palmerston near Innisfail on Saturday.
His green Kawasaki struck a pole and he was pronounced dead at the scene.
Nearly two hours later, a black Honda motorbike collided with a Kia Cerato in Thornlands, about 30km southeast of the Brisbane city centre.
The 18-year-old rider died after being transported to hospital with critical injuries. The Kia driver was uninjured.
In South Australia, two men, one riding a Honda motorcycle and the other a Suzuki, died in a collision at Paracombe in the Adelaide Hills about 2.30pm on Saturday.
Another SA man, riding a Harley Davidson, died on Friday after police said he crashed into a traffic light.
While in NSW, a man in his 40s, travelling with several other motorbike riders, crashed on the Monaro Highway near Cooma on Friday and died at the scene.
In other road deaths, a mother-of-four from interstate was killed after a crash in Queensland.
The 51-year-old Victorian was a passenger in a Ford hatchback travelling on School Road in Logan Reserve, south of Brisbane, about 9pm on Saturday when her car was hit head-on by a Ford Falcon utility.
The victim, who had been returning from a family celebration, died at the scene.
Her 21-year-old niece sustained serious leg and back injuries, while a one-year-old child in the car miraculously escaped harm.
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