The crash happened Saturday 1:42 p.m. in the 4000-Block of Route 34 near Wolf Road in Oswego, police said.
A 20-year-old man riding a motorcycle eastbound on Route 34 when it crashed into a trailer being towed by a van as it was attempting to turn right into a driveway, police said.
The motorcyclist was taken to a hospital, where he died. He has been identified as Stone Antrim, 20, of Oswego.
Police said witnesses reported seeing multiple motorcycles traveling together in the area before the crash and traveling at a high rate of speed.
Investigators said the van involved in the crash was lawfully attempting to turn into a driveway with its turn signal activated at the time of the crash.
No other injuries were reported in the crash.