Motorcycle Basics: Power Knowledge

Power Knowledge

Horsepower (hp) was initially defined by the French and Germans. However, the horses they used to measure horsepower were smaller than average horses. Therefore, an engine rated at 50 hp shouldn’t be imagined as being pulled by 50 full-sized horses—it’s more appropriate to think of it as equivalent to about 35 horses.

The unit “ps” was first used by Germans to represent horsepower and is still used today.

What is 1 horsepower?
1 horsepower is the power needed to lift a 75 kg object by 1 meter in 1 second. On specifications sheets, for example, “70 ps / 8000 rpm” means the engine produces 70 horsepower at 8,000 revolutions per minute.

RPM stands for “revolutions per minute,” which indicates how many times the engine rotates in one minute.

What is torque?
Torque, also called rotational force, is the turning force applied to an axis. Its common unit is kg-m (or Nm in the International System).

Understanding torque with examples:

• If you use a screwdriver or wrench that is 1 meter long and apply 1 kg of force at the end, the torque applied to the screw is 1 kg-m.

• If the tool is only 0.5 meters long, you must apply 2 kg of force to achieve 1 kg-m of torque.

• Conversely, for the same driving torque, the farther from the rotation center, the smaller the force generated.