Should You Shift Gears Based on RPM or Speed?
2 Answers
Shifting gears is primarily based on RPM. The reason a car needs to shift gears is due to new demands on the torque provided by the engine, and the torque the engine can provide is directly related to RPM. It's important to note: For a specific car model, the engine RPM corresponds to a particular speed in different gears. If you know this specific correlation, you can also shift gears based on speed. Different engines have varying power and torque output characteristics, so the corresponding shift RPM also differs. For example, some recommend shifting at 2000 RPM, while others suggest shifting at 2200 RPM.
When shifting gears, I mainly rely on the tachometer because the RPM directly indicates the engine's working condition. If the RPM is too low, such as below 1500, the car will shake, lack power, and accelerate slowly; if the RPM is too high and exceeds the redline, the engine is prone to overheating and wear. Vehicle speed can be used as a supplementary reference, like shifting to third gear at 50 km/h, but it changes slowly and is less precise. During city commuting, I'm accustomed to keeping the RPM between 2000-3000 for fuel efficiency and quiet operation, while on highways, I rev up to 6000 RPM for a powerful upshift when overtaking. With more experience, you realize that RPM is the soul of gear shifting—it predicts engine load and prevents stalling or damage.
