A crazed cyclist went berserk and smashed the drive-thru window of a Bronx Burger King with a bike chain after being refused service for not being in a car, cops said Tuesday.

The suspect pedaled up to the drive-thru window of the fast-food joint on East 149th Street near Brook Avenue in Mott Haven at about 7:50 p.m. on Aug. 27, police said.

He then shouted at one of the fast food employees and leaned his head into the window while pointing at his cellphone, video of the altercation shows.

Moments later, he beat the window with a bike chain, police said.

The window shattered and the man pedaled off, according to cops.

No one was injured during the fracas, but police are searching for the suspect.