A "plunger motorcycle" refers to a specific type of motorcycle suspension system that was commonly used in older motorcycles, particularly those produced in the mid-20th century. The term "plunger" refers to the design of the rear suspension.
In a plunger suspension system, the rear wheel is connected to the frame through a pair of telescopic tubes or "plungers." These plungers are essentially hydraulic or spring-loaded dampers that provide suspension travel and absorb the shocks and bumps encountered while riding.
The design of a plunger suspension system typically consists of a pair of hydraulic dampers enclosed within the telescopic tubes. As the wheel encounters bumps or uneven surfaces, the plungers compress and extend to absorb the impact and provide a smoother ride.
Plunger suspensions were common on motorcycles manufactured in the 1940s and 1950s, especially in British motorcycles like Triumph, BSA, and Norton. However, this type of suspension system has largely been replaced by more advanced and efficient designs, such as swingarms with shock absorbers or modern monoshock setups.
Plunger suspensions, while effective for their time, had limitations in terms of performance, adjustability, and ride quality compared to modern suspension systems. Today, motorcycles typically use more sophisticated suspension technologies to enhance handling, comfort, and stability.