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 (physics)|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.<ref name=Searle2009>{{citation |last=Searle |first=Dave |magazine=[[Motorcycle Consumer News]] | ___location=Irvine, California |publisher=Aviation News Corp |issn=1073-9408 |title=Measures |page=2 |date=October 2009 |volume=40 |issue=10 |url=http://www.mcnews.com/mcn/editorials/2009OctOpenRd.pdf |access-date=2010-04-29}}</ref> 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 [[Motorcycle transmission|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.
