Werewolves on Wheels (1971)

A biker gang visits a monastery where they encounter blackrobed monks engaged in worshipping Satan When the monks try to persuade one of the female bikers Helen to become a satanic sacrifice the bikers smash up the monastery and leave The monks have the last laugh though as Helen as a result of the satanic rituals is now possessed and at night changes into a werewolf with dire results for the biker gang