During closing arguments on Monday, a prosecutor and a defense lawyer each described the moment that Mr. Lewis — steering his bus down a stretch of road narrowed by vehicles parked on both sides of the street — collided with Mr. Hanegby, who fell to the ground and was run over.

But they offered far different explanations of who was to blame.

“There was ample time and ample location for this bicyclist to pull over,” a defense lawyer, Jeremy Saland, told the judge overseeing Mr. Lewis’s trial, adding that the bicyclist had been “completely and totally unaware” of his surroundings.

None of that mattered, according to a prosecutor, Raffaela Belizaire.

“Dan Hanegby had the right of way,” she countered. “The defendant thought that the cyclist should move over, not that he himself should have slowed down.”

After the judge, Heidi Cesare, found him guilty, Mr. Lewis left the courthouse without comment. When sentenced Oct. 22, he faces up to 30 days in jail for failing to yield the right of way, and up to 15 days imprisonment for failing to exercise due care.

Bicycling advocates found validation in the verdict.

“Drivers are rarely held accountable for recklessly taking lives on New York City streets,” said Paul Steely White, executive director of Transportation Alternatives. “All too often, police hastily exonerate drivers while erroneously blaming bicyclists and pedestrians for their own deaths.”