What is the use of science in the structure of the bicycle?

Modern bikes are very complex and sophisticated.

Take, for example, the shifting system of a mountain bike.

In order to shift gears accurately, the chainring and toggle system must be precisely matched, and the shape of each tooth is different in the advanced mountain bike, and there are many points of different sizes welded on the disc to enable faster and more precise gear shifts, and the accuracy of the toggle system is also measured in microns.

The body is based on the principle of derivation, with stable triangular support and large load-bearing.

The transmission and foot are both the principle of levers, and the size of the wheel and the number of teeth are the principle of gear shifting.

The handlebars are patterned to increase friction.

<>1. Among the 25 components of the bicycle, such as frame, tires, pedals, brakes, and chains, the basic components are indispensable. Among them, the frame is the skeleton of the bicycle, and it carries the most weight of people and cargo. According to the working characteristics of each rubber and lead component, it can be roughly divided into guide system, drive system and braking system.

2. Guidance system: composed of handlebar, front fork, front axle, front wheel and other components. The rider can change the direction of travel and maintain body balance by manipulating the handlebars.

Drive (transmission or walking) tie beam grip system: composed of pedals, bottom bracket, sprocket, crank, chain, flywheel, rear axle, rear wheel and other components. The pedaling force of the human foot is transmitted by the pedal through the crank, sprocket, chain, flywheel, rear axle and other components, so that the bicycle continues to move forward.

Braking system: It is composed of brake parts, and the rider can operate the brake at any time to slow down the moving bicycle, stop it, and ensure driving safety.

1. Knowledge of mechanics.

1. Friction.

1) Some patterns are engraved on the tires, handlebar covers, pedals and brake pads of the bicycle to increase the roughness of the contact surface and increase the friction.

2) Some lubricating oil is often applied to the axle to reduce the roughness of the contact surface and reduce the friction.

3) There are balls at all axles, which change the sliding friction to rolling friction to reduce friction and rotate conveniently.

4) when braking, need to tighten the brake handle, to increase the pressure between the brake block and the rim, thereby increasing the friction, 5) when the bicycle is pressed forward, the direction of friction that the rear wheel receives is forward, is the power of the bicycle forward, and the direction of the friction force received by the front wheel is backward, is the resistance of the bicycle forward;

When the bicycle moves forward by inertia, the friction force experienced by the front and rear wheels is in the direction of backwards, and both forces are the resistance of the bicycle to move forward.

2. Pressure.

1) In general, the landing area of a fully inflated bicycle tire is approximately.

s=2 10cm 5cm=100 cm2, when an ordinary adult rides a bicycle forward, the pressure of the bicycle on the ground is about f=(500N+150N)=650N, and the pressure of the bicycle on the ground can be calculated as.

2) A washer should be added to the nut of the axle to increase the stress area and reduce the pressure.

3) The pedal of the bicycle is made flat and flat to increase the force area to reduce its pressure on the foot, 4) The inner tube of the bicycle should be filled with enough gas, and when the volume and temperature of the gas are constant, the greater the mass of the gas, the greater the pressure.

5) The saddle of the bicycle is made flat and flat to increase the force area to reduce its pressure on the body.

3. Axles.

2) The pedal and bottom bracket of the bicycle are also equivalent to an axle, which is essentially a labor-saving lever.

3) The flywheel of the bicycle is also equivalent to a labor-saving axle.

4. Leverage.

The brake handle of the bicycle is equivalent to a low-effort lever.

5. Inertia.

1) When a person is riding a bicycle forward, after stopping pedaling the bicycle, the bicycle still walks forward, which is due to its inertia.

2) When a person rides a bicycle forward, if there is an emergency, it is generally necessary to pinch the rear brake first, and then pinch the front brake, or pinch the front and rear together, which is done to prevent people from flying forward due to inertia.

There is a triangle between the front and rear wheels, especially with beams, and the triangle is used for stability.

A lot. The gyroscopic principle (physics), the main balancing principle of bicycles, is actually a phenomenon of inertia.

The power of the bicycle and the principle of shifting – the classic drivetrain consisting of driving wheels, driven wheels, and conveyor belts (chains). Shifting is done by changing the size ratio of the driving wheel and the driven wheel.

Now there are two mainstream brake components, one is the classic caliper with rubber on it, through the tightening of the caliper, the rubber rubs against the rim to slow down the car. Since this part looks like an inverted V-shaped from the cross-section, it is called a V-brake. There are also more advanced and effective disc brakes, similar to car brakes.

It is to use a substance on the clamp that is conducive to heat dissipation and has a large wear resistance, and by rubbing with the disc next to the bottom shaft (hub) of the wheel, this substance is "smeared" on the disc as evenly as possible, and then by tightening the clamp, greater friction can be obtained. INTERVIEWER Actually, chemistry and physics are involved here. V brake uses rubber because the molecular structure of rubber is stable, and the intermolecular mechanical structure is also stable (of course, the rubber here is a mixture, and carbon and other substances are added to make it tougher), which is not easy to wear, and the rubber itself is tough, and it is not easy to damage other parts when rubbing.

In addition, it seems that both types of braking reduce the speed of the vehicle through friction, but in fact it is a kind of energy conversion: the bicycle has kinetic energy when it is in motion, and when it brakes, the braking device converts the kinetic energy of the bicycle into another energy - heat through friction. Overheating has an impact on the life of the mechanical components (which in turn involves other knowledge), so the resistance material used on the disc brakes mentioned above is a material that is good for heat dissipation.

After the V brake generates a large amount of heat, the carbon element in the rubber will be "carbonized" and crystallized into a carbon substance, and the top of the wheel is all black. To get back to business: materials science, chemistry, energy conversion in physics, and ...... are involved

In order to increase speed, professional racing bikes are also specially designed to reduce air resistance - aerodynamics.

In order to make the riding more comfortable for cyclists and racers, special designs will be made in the handlebars and saddles, such as the heat dissipation holes on the saddle - ergonomics.

The beautiful paint paint on the body involves chemistry.

And so on......

Knowledge of mechanics included in the bike.

1. The bicycle is a transmission machine, and its transmission device includes active gears, passive gears, chains and transmissions. The flywheel under the chain drive drives the rear wheel to rotate The flywheel has the same angular velocity as the rear wheel, and the radius of the rear wheel is much greater than the radius of the gear Increase by the linear velocity, and the vehicle speed is improved.

2. The brake handle and connecting rod in the bicycle braking system are a labor-saving lever, which can increase the pulling force on the brake pad. In order to save effort or distance, the bicycle also uses axles: pedal plates and sprocket cranks; Rear wheels and flywheels, faucets and rotating shafts, etc.

3. The front axle, middle axle and rear axle of the car are made of balls, and the sliding friction is changed to rolling friction. To further reduce friction, lubricants are often applied to these areas.

4. The tires, handlebar covers, pedals, etc. of the bicycle are engraved with uneven patterns to increase friction.

Look at the science textbook kid, the fifth grade is still the fourth grade.

1.We can ride it forward, and the tires have friction, action and reaction.

2.Stepping on the foot pedal, it feels very easy lever principle, labor-saving lever.

3.The chain drives the frisbee and gears with linear and angular velocity.

4.Stool increases the force area and makes people feel comfortable.

5.The tires are connected by steel wires to reduce the force area and reduce the impact of crosswind on the balance of the bicycle.

Can't think of it.

Foot pedal rotation - > gear rotation, torque conservation; Rear-wheel drive, front-wheel driven, and frictional force backward and forward respectively, involving the principle of action and reaction, as well as the principle of force balance; The direction of rotation involves the principle of leverage.

The wheels of the bicycle have a rough surface to increase friction.

The handbrake uses the principle of leverage.

Brakes use increased pressure to increase friction.

The wheels are round, and friction is reduced by changing the slide to roll.