Other difficulties you may encounter while building bikes include motorizing the steering system, the limited variety and size of matching LEGO wheels, and the overall small size and exposed body, which make it difficult to install any large eletric components. All in all, motorcycles are aesthetically interesting models to build but difficult ones to motorize. Among the LEGO sets, as well as amomg MOCs, most motorcycles have only basic functions, such as a suspension system and drivetrain with a replica of an engine, while motorized models are a rarity. For an example of a motorized model, see Figure 19-9.