The 23-year-old bicyclist, on a Citi Bike, was northbound when he was struck by a bus turning southbound from West 41st Street at 4:55 a.m.
The victim was taken to Bellevue Hospital in critical condition.
The bus, operated by NY Waterways, stopped and stayed at the scene.
Northbound West Side Highway would reopen upon the conclusion of the investigation.
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