Mark Landry on his motorcycle. (Robotech: The Movie)
Motorcycles were a type of transportation on Earth. Mark Landry worked in a motorcycle shop, and also rode one. This is likely why his friend Todd trusted his with the MODAT-5, a top-secret mecha project in the form of a bike. (Robotech: The Movie)
Later, the Cyclone was used, which was very similar to the MODAT-5. (Robotech: The New Generation)
Dusty Ayres used an MT-21 Dauntless armored assault motorcycle during his revenge crusade.