The unknown bicyclist was hit around 6:40 p.m. Saturday, after he rode into the intersection of Imperial Avenue from northbound South 47th street.
The young man, currently at Scripps Mercy Hospital, is described as a young Black man between 15 and 19-years-old.
He was hit by a man driving a black Chevrolet Trailblazer, according to the San Diego Police Department.
Police say he hit his head on the curb after he fell off of his mountain bike, causing a serious injury. He was not wearing a helmet.
He did not have any form of identification on him and the grey HTC One smartphone found on him was not working. Police say nothing has turned up from fingerprinting or facial recognition comparisons.
As of Wednesday, they have been unable to find any missing person or runaway juvenile reports related to the case.
Anyone who has information on the possible identity of this person is asked to call the San Diego Police Department.