Motorcycle testing and measurement

Motorcycle testing and measurement includes a range of more than two dozen statistics giving the specifications of the motorcycle, and the actual performance, expressed by such things as the output of the engine, and the top speed or acceleration of the motorcycle. Most parameters are uncontroversial and claims made by manufacturers are generally accepted without verification. These might include simple measurements like rake, trail, or wheelbase, or basic features, such as the type of brakes or ignition system.

Other measurements are often doubted or subject to misunderstandings, and the motorcycling press serves as an independent check on sometimes unrealistic sales and marketing claims. Many of these numbers are subject to variable methods of measurements, or disagreement as to the definition of the statistic. The parameters most often in contention for motorcycles are the weight, the engine output (power and torque), and the overall performance, especially acceleration, top speed, and fuel economy. With electric motorcycles and scooters, the range between charges is often a pivotal measurement.

Motorcycle speed tests, especially at high speeds, are prone to variation due to human error, limitations in equipment, and atmospheric factors like wind, humidity, and altitude. The published results of two otherwise identical tests could vary depending on whether the result is reported with or without industry standard correction factors calculated to compensate for test conditions. Rounding errors are possible as well when converting to/from miles and kilometers per hour.

With power typically being the product of force and speed, a motorcycle's power and torque ratings will be highly indicative of its performance. Reported numbers for power and torque may however vary from one source to another due to inconsistencies in how testing equipment is calibrated, the method of using that equipment, the conditions during the test, and particularly the location that force and speed are being measured at. The power of the engine alone, often called crankshaft power, or power at the crankshaft, will be significantly greater than the power measured at the rear wheel. The amount of power lost due to friction in the transmission (primary drive, gearbox and final drive) depends on the details of the design and construction. Generalizing, a chain drive motorcycle may have some 5-20% less power at the rear wheel than at the crankshaft, while a shaft drive model may lose a little more than that due to greater friction.

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