At the heart of the 2021 Aprilia RS 125 sport motorcycle, Aprilia utilizes a 124.2 cc (7.6 cu in) liquid-cooled single cylinder, four-stroke layout. In factory specification, peak output is rated at 14.8 HP (10.8 kW), transferring power to the rear wheel through a 6-speed gearbox and chain final drive. With a specific output of 119.2 HP per liter, the engine character is reflecting a performance-oriented street tune that balances strong mid-range pull with an energetic top-end rush.
On the scales, the RS 125 measures 144 kg (317 lbs) wet (curb), translating to a power-to-weight ratio of 0.1 HP/kg (9.73 kg per horsepower). Rider ergonomics and chassis geometry center around a 820 mm (32.3 in) seat height — resulting in a taller command-style riding posture suited to medium-to-tall inseams, combined with a 1,353 mm (53.3 in) wheelbase engineered for quick, flickable steering geometry. The 14.5-liter (3.8 US gal) fuel tank supports practical everyday commuting and weekend road stints.
Within MotoLibrary's Aprilia archive, this model family spans 21 indexed model years from 1997 to 2025, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.
Use this page to compare this motorcycle by its real specifications, not only by model name. Focus on the details that affect fit, comfort, handling, range and ownership.
Power
Compare engine output with similar motorcycles if acceleration, highway use or two-up riding matters.
Seat Height
Check the seat height against your inseam and riding posture before choosing a motorcycle.
Fuel Capacity
Fuel capacity helps estimate touring range and how often you may need to stop.
Brakes
Brake setup is worth comparing if you ride in traffic, mountains or with a passenger.
Suspension
Suspension details can matter for comfort, road feel and long-distance riding.
Transmission
Transmission and final drive affect maintenance, smoothness and everyday usability.
