A smaller rear sprocket on a motorcycle has the effect of increasing the overall acceleration of the bike while sacrificing some top speed. The rear sprocket is connected to the motorcycle's rear wheel and is part of the gearing system. It works in conjunction with the front sprocket to determine the final drive ratio of the motorcycle.
Here's how a smaller rear sprocket affects the motorcycle's performance:
Increased acceleration: A smaller rear sprocket effectively increases the gear ratio, which means that for each revolution of the engine's crankshaft, the rear wheel will rotate more times. This results in a quicker transfer of power from the engine to the rear wheel, enhancing acceleration. The bike will reach higher RPMs in each gear, allowing for faster acceleration off the line and in lower gears.
Reduced top speed: While a smaller rear sprocket improves acceleration, it simultaneously reduces the top speed potential of the motorcycle. Since the engine is rotating the rear wheel more times per revolution, the overall gearing is shorter, which limits the top speed attainable. The engine may reach its RPM limit at a lower speed, preventing further acceleration.
Increased engine RPM: With a smaller rear sprocket, the engine will operate at higher RPMs for a given speed compared to a larger sprocket. This can affect fuel efficiency and engine stress, as higher RPMs generally result in increased fuel consumption and engine wear.
More responsive throttle: The shorter gearing provided by a smaller rear sprocket can make the throttle response feel more immediate and sensitive. This can be desirable for riders who prefer a more aggressive and lively feel when accelerating from a standstill or exiting corners.
It's important to note that altering the sprocket sizes can have significant effects on the overall performance characteristics of the motorcycle. The choice of sprocket size depends on your riding preferences, the motorcycle's power delivery, and the intended use of the bike (e.g., track racing, commuting, or off-roading). It's recommended to consult with experienced motorcycle technicians or riders who have expertise in sprocket modifications to ensure the changes align with your specific needs and the capabilities of your motorcycle.