Dynamics
Main article: Bicycle and motorcycle dynamics
A bicycle stays upright while moving forward by being steered so as to keep its center of gravity over the wheels.[9] This steering is usually provided by the rider, but under certain conditions may be provided by the bicycle itself.[10]The combined center of mass of a bicycle and its rider must lean into a turn to successfully navigate it. This lean is induced by a method known as countersteering, which can be performed by the rider turning the handlebars directly with the hands[11] or indirectly by leaning the bicycle.[12]
Short-wheelbase or tall bicycles, when braking, can generate enough stopping force at the front wheel to flip longitudinally.[13] The act of purposefully using this force to lift the rear wheel and balance on the front without tipping over is a trick known as a stoppie, endo or front wheelie.