How much speed can be increased by changing from 15 to 17 teeth on a motorcycle?
4 Answers
Changing from 15 to 17 teeth on a motorcycle can increase the speed by approximately 1.2 times. Definition: Motorcycle, a two-wheeled or three-wheeled vehicle powered by a gasoline engine and steered by handlebars to control the front wheel. It is lightweight, flexible, and fast, widely used for patrol, passenger and cargo transportation, and also serves as sports equipment. Broadly speaking, motorcycles are categorized into street bikes, road racing motorcycles, off-road motorcycles, cruisers, touring bikes, etc. Origin: In 1885, German Gottlieb Daimler installed an engine into a framed machine, giving birth to the world's first motorcycle. Motorcycle sports, related to motorcycles, are a type of military sports activity, serving as a competitive sport using motorcycles as equipment. They are divided into two-wheeled and three-wheeled models, with each model categorized into several classes based on the engine cylinder displacement.
I used to modify motorcycles, and after changing the front sprocket from 15 teeth to 17 teeth, the theoretical speed increased by about 13%. This is mainly because it alters the gear ratio, reducing the rotation ratio and allowing the wheel to spin faster at the same engine RPM. However, in reality, the actual speed gain depends on the specific model and engine performance. On my 150cc bike, the top speed increased from 115 km/h to 130 km/h, with noticeable improvement during high-speed cruising. That said, acceleration from a standstill becomes slower after the modification due to reduced torque, requiring more throttle input in city riding. The chain length also needs to be adjusted accordingly; otherwise, chain wear accelerates. It's recommended to have this done professionally and to test the braking system, as increased speed may affect stability and pose risks. Overall, this modification suits riders seeking higher speeds, but without altering engine power limits, the speed gain typically ranges between 10-15%.
As a rider who frequently travels long distances, I changed the front sprocket on my motorcycle from 15 teeth to 17 teeth, and I feel that the top speed has increased by about 15%. The previous limit was only 120 km/h, but now it easily reaches 138 km/h, making high-speed riding smoother and more stable. However, the downside is sluggish low-RPM response, making the bike feel heavier when starting in the city—requiring more throttle to keep up with traffic lights. Fuel consumption has also slightly increased because the engine often operates in higher RPM ranges. During the modification, it's essential to check the chain and tire pressure to ensure they match the 17-tooth specification; otherwise, chain skipping or rapid wear may occur. I think this modification is perfect for highway enthusiasts—the speed boost saves time on long trips—but don’t expect a massive leap, as the engine’s inherent factors play a significant role.
I've modified the sprocket, changing from 15 to 17 teeth usually increases speed by about 10-12%. A simple calculation is original teeth 15, new 17, the gear ratio change results in a speed increase of approximately 1/0.88 times. Actual performance depends on the engine; my car's speed increased by about 12km/h, but with some loss in acceleration performance. Remember to adjust the chain tensioner simultaneously to avoid slack or abnormal wear. Additionally, consider tire wear rate and the braking system, prioritizing high-speed stability and safety.
