The Forensic Crash Unit is investigating the circumstances of a serious traffic incident involving a bicycle and vehicle at Underwood yesterday.
Initial inquiries indicate between 6.40am and 7.10am the 55-year-old cyclist was riding on Logan Road near the intersection of Kingston Road.
The man was riding north on the left-hand side when he was struck by the Toyota Camry sedan as it exited Kingston Road.
He was thrown some distance, coming to rest in one of the adjacent lanes.
The man was taken to the Princess Alexandra Hospital with serious head injuries.
The driver of the sedan, a 29-year-old man, was not injured in the crash.
Investigators are appealing for anyone travelling in the vicinity around the time of the crash, with dashcam footage, to contact them.
Investigations are continuing.
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You can report information about crime anonymously to Crime Stoppers, a registered charity and community volunteer organisation, by calling 1800 333 000 or via crimestoppersqld.com.au 24hrs per day.