He was pronounced dead at the scene.
The driver, also believed to be in his 20, stayed at the scene and was being questioned by detectives.
The B41 buses were rerouted for the police investigation.
No charges were immediately filed.
Bicyclist fatally struck on Flatbush Ave.
FLATBUSH Investigators say the victim, a man in his 20s, was hit at the intersection of Flatbush Avenue and Duryea Place just before 9:30 a.m..
