Authorities said It happened around 2:45 Sunday afternoon. Belfast police, fire, and ambulance were called to Searsport Avenue on Route 1.
Police said upon arrival they found the teen with serious injuries and unresponsive on the side of the road with a damaged bicycle. The car involved was also on scene.
Police said the teenager was transported to a Bangor hospital and no charges have been filed on the operator of the car, who police say has been cooperative with them.
They do not believe speed or impaired driving was to blame. The accident is being reconstructed and is under investigation.
Police said no names are being released at this time.