If bikers are wearing it its not a Maltese cross, its an iron cross, a symbol made popular by the chopper (motorcycle) generation in America back in the sixties. :)
The Maltese cross is known around the world as a symbol of the fire service. It is often seen painted on fire trucks, on the clothing of firefighters, depicted on firefighter's badges, and is quite...
The Maltese cross originally from the Knights of St John of Jerusalem ( the Knight Hospitalers)who used the Christian cross as a badge on their shields was adopted by the St. John Ambulance Brigade...