Police are looking for any witnesses after a cyclist was found lying on the sidewalk of the Burgoyne Bridge just before 9:30 p.m. Sunday night
They say a 57-year-old St Catharines man was riding his bicycle on the bridge when he fell and struck his head on the sidewalk.
The man suffered life-threatening injuries and was air lifted to an out of town hospital.
The Niagara police reconstruction unit is investigating.
Any witnesses are asked to contact police.