The working principle of bicycle is one of the most difficult problems in the world. Why do you say that?

The birth of bicycle is purely from life experience. Bicycles were invented by the French in the18th century. The first bike is a real "bike". Yes, it walks on the ground with both feet. You have to get off and walk around when turning. To put it bluntly, it is a piece of wood with two wheels. This is a simple idea.

This kind of invention is naturally meaningless, so soon a German forest keeper named delaisse added a rotatable handle to it, at least it didn't need to move. Miraculously, such an unremarkable thing has been transformed by many people and has appeared in countless shapes.

Finally, an Englishman named Lawson couldn't stand it anymore, so he installed a hinge on his bike. This kind of hinge transmission system has large front gear and small rear gear, which not only saves labor, but also makes the wheels as big as before. This shape was finally finalized and has been passed down to this day. In other words, in the whole history of bicycle development, scientists have never participated in it, relying entirely on the wisdom and life experience of working people.

In fact, there are many such things in the real world. People only know how to do this, but they don't understand why. But after things were made, scientists finally stepped in and began to explore the essence.

In the bicycle theory that has dominated for hundreds of years, the "front wheel gyro effect" is to rotate around a central point, not only around its own central axis, but also around a bottom point. As long as the gyro rotates fast enough and the swing is small, the gyro will not fall off. This kind of rapidly rotating gyro not only won't fall down, but even if it is subjected to external force, it will only shift without falling down, such as a bicycle that corrects itself on a rugged road.

This phenomenon is called "angular momentum". This is obviously an acceptable theory, intuitive and simple. So it ruled the world for more than a hundred years and appeared in many popular science books.

The theory that the front wheel wake destroyed the gyro effect was questioned by many people during the reign of gyro effect.

For example, the physicist Sommerfeld believes that if the "gyro effect" dominates the balance of bicycles, then the wheels of bicycles should use the edges of heavy wheels and tires as much as possible to enhance this effect, but the fact is just the opposite. As can be seen from the structure of the wheel, the gyro effect is actually very small.

But what really broke this theory was david jones, an Englishman, who put forward the theory of front wheel wake. The core of the front wheel wake is that the center of gravity should be constantly adjusted. When the bicycle is upright, the front wheel does not deflect forward, but if the bicycle is tilted by an angle, the front wheel of the bicycle will also deflect by an angle.

There is a functional relationship between the front fork point of the bicycle and the inclination angle of the bicycle and the deflection angle of the front wheel. He used a computer to calculate this functional relationship, that is, the center of gravity of the bicycle that landed returned from the top to the bottom, thus maintaining the balance of the bicycle. Just like when we ride a bicycle, we will consciously correct the front of the bicycle in the same direction to make it return to normal.

The core of scientists' experimental scientific verification of bicycle balance principle is that if this principle is removed from the bicycle, the bicycle balance system will fail. For scientists, naturally, they can't rely on intracranial science for sophistry like some people, and all theoretical sciences ultimately rely on experimental science to falsify.

Facing the bicycle, the scientist's method is to build a bicycle that lacks a certain principle and observe whether it still keeps balance. Juns made a bicycle with two front wheels. The two front wheels of this bicycle are parallel to each other and rotate in opposite directions at the same speed to counteract the angular momentum in the gyro effect.

Miraculously, this bicycle can walk freely, so the theory of "gyro effect" is self-defeating.

These scientists have built a perverted bicycle, which not only has four wheels to counteract the angular momentum of the front and rear wheels at the same time, but also has the negative wake of the front wheels. It's a pity that this bike is still pushing in the gym and running freely until the speed runs out. The researchers even gave the bicycle a push during its automatic driving, but soon the car automatically adjusted to a straight track.

The only discovery is that people find that if the faucet of this bicycle is fixed, it will not be able to keep balance, but they still don't know why. So today, the problem of bicycles not falling down has not been solved. Scientists can only vaguely feel that the gyro effect, the front wheel wake and the front center of gravity of the bicycle may affect the balance of the bicycle in an internal relationship.

The application of bicycles by human beings is more like that human beings are adapting to bicycles. Therefore, in nature, only a few animals such as humans and monkeys can ride bicycles. Behind the bicycle, the biological brain may be a bigger mystery.