Harley-Davidson primarily uses the Imperial system (inches and pounds) for measuring and labeling components on their motorcycles. Historically, Harley-Davidson motorcycles have been manufactured and marketed in the United States, where the Imperial system is the prevailing standard of measurement.
Some components, particularly those sourced from international suppliers or designed for global models, may use metric measurements.
Additionally, as motorcycles become more globally standardized, there may be instances where Harley-Davidson incorporates metric measurements or components to align with international norms or meet regulatory requirements in specific markets.
In summary, while Harley-Davidson primarily uses the Imperial system, there may be instances of metric measurements or components in certain models or international versions of their motorcycles.