An innocent bike ride by an elderly man through East Harlem on Thursday afternoon turned into a violent nightmare. In an apparent random attack, the 74-year-old was ambushed by a stranger who then viciously battered him with his own bike, police said. Cops said the cycling septuagenarian was pedaling along just minding his own business at Pleasant Ave. and E. 114th St. shortly before 4 p.m. when the unidentified male shoved him off his two-wheeler, then punched him several times in the face. Adding insult to injury, the unhinged attacker then beat the victim with his own bicycle, causing lacerations to the senior’s head and torso. The assailant then fled on foot. EMS transported the victim to Metropolitan Hospital Center in stable condition. Police ask anyone with information to call the NYPD Crime Stoppers hotline at 1-800-577-TIPS (8477). All calls are confidential.