When turning to the right or left with a bicycle, what is the physical movement that is unknowingly happening?

When I am feeling a big deep feeling about my childhood and becoming able to ride a bicycle, I will be able to manipulate my bicycle freely without considering almost anything. In other words, I am mastering my bicycle in the state of "learning the body", but when I am actually riding a bicycle, humans are doing unexpected movements in an almost unconscious state.

The Counterintuitive Physics of Turning a Bike - YouTube


For example, when you are riding a bicycle and trying to bend to the right.


At this time, simply by bending the steering wheel in the right direction ......


I can not turn to the right properly, but on the contrary it will proceed to the left. This is because the car body tilts to the opposite left when bending the steering wheel to the right while keeping the straight traveling state, and it will naturally start to turn left.


If you are a four-wheeled vehicle it is a good idea to turn the tire in the direction you wish to advance, but in the case of a two-wheeled bicycle the situation will be different. The difference lies in the place where the action "tilting the car body" concretely occurs.


In the case of a bicycle, the first "trigger" is necessary. In this way, when lightly cutting the steering wheel to the right ......


The car body tilts to the left. At this time, due to the mechanical relationship between the angle of the fork that supports the front wheel, the installation point of the tire, the weight of the car, etc., the front wheel changes its direction naturally to the left.


Then, depending on the direction of the front wheels, the bike will have the force to move left. In this way, while leaning the car lightly to the left, the bicycle proceeds in the direction opposite to the direction in which the handle was first turned off.


This is exactly the opposite even if you want to go to the right. When I think "I want to go to the right", firstly lightly cut the handle to the left ... ...


As a matter of course, the car body is about to fall in the right direction. And by the action of the same mechanics as before ... ...


This time when the car body is tilted to the right, the handle cuts to the right, and the bicycle will go to the right direction as it is. It is said that this first handle is almost unconsciously done, and in fact it is only a slight angle, so there is little to be recognized.


This movement is being created in two-wheeled vehicles such as bicycles and motorcyclesSelf-steeringWork that. Generally, when a two-wheeled vehicle tilts in either direction to the left or right, the force which tries to cut inward to the front wheel is larger than the angle at that time. When that force is applied, the power of cornering will become stronger, but this time the body will try to rise due to the action of the centrifugal force acting on the car body. In other words, cornering of the bicycle is established by antagonism of this cutting power and the force trying to rise.


While the bicycle is cornering, the person actually riding does not have to be conscious, but the power to turn the handle down slightly in the direction opposite to the direction of advance is working.


If you read the following article that explains this movement in a bit more detail, you can see why the bicycle runs without collapsing, its mechanism.

Explain why bicycles can keep running without falling down, and explain the mechanism by animation - GIGAZINE


To put it simply, one of the reasons why a bicycle keeps running without collapsing is because the front fork supporting the front wheel is angled. As a result, there is a gap between where the extended line of the front fork's rotation axis hits the ground and where the front tire actually contacts the ground.


If you tilt the car body to the left in that state, for example, the handle tries to cut to the left largely due to the weight of the car body. It is thought that this force is creating stability during cornering.


Also, the position of the center of gravity of the steering wheel and the tire is located in front of the axis of the front fork ... ...


The "gyroscopic effect" which is born by the rotation of the tire means that the bicycle can bend and also to make it possible to run straight.