A cyclist has died after being found unconscious on the side of the road in West Swan last night.

The 39-year-old Ellenbrook man was discovered by a member of the public at 9.30pm after the rider struck a power pole on a bike fitted with a petrol engine on West Swan Road.

The man, who has yet to be identified, was taken to Royal Perth Hospital where he died this morning.

Police are investigating the death.