The Crusader "Cruiser" model was the high-end (more expensive) men/boy's bicycle, and included additional features, such as front headlight, rear rack, and most importantly, the motobike tank.
In an old catalog from Sears, Roebuck and Company, the Elgin Motor Bike was advertised, and the term motor-bike was explained as follows, "The term "Moto-Bike" has reference only to the type of frame, meaning that it is built on the order of a motorcycle".