The Harley-Davidson Sportster was the first model sold with a factory-installed front disc brake.
Harley-Davidson introduced the disc brake on the Sportster in 1972, replacing the earlier drum-brake arrangement. Disc brakes generally offer more consistent stopping performance and better heat management than drum brakes, making them especially useful as motorcycle performance and speeds increased.
The Sportster began in 1957 as a compact performance-oriented model powered by the Ironhead engine. Although its styling remained recognizably Harley-Davidson, the model served as an important bridge between traditional cruiser design and more modern braking and chassis technology.
This fact is sometimes confused with the introduction of disc brakes on other Harley-Davidson families. The question refers to the first factory-installed front disc brake in the company’s motorcycle lineup, not the first rear disc brake or the first optional brake component. Later Sportster versions adopted further improvements, including rear disc brakes and electronic fuel injection.