1.The reflector of the bicycle serves as a warning.

The principle of the bicycle reflector is actually very simple, that is, the light is reflected in the plate: the incident weight angle is equal to the reflection angle. The light coming from which direction is reflected back to which direction, so if the position is in the same direction as the light source, it will be very bright. And within a certain angle range.

Due to the relationship between incidence and reflection, the actual structure is reversed, so it must also consider the relationship between the angle of refraction. The materials used are mainly polystyrene plastics with better optical properties. When the rear lights shine, the bicycle will be easy to spot. There are also installations on the side and front, which is a consideration of protection from different directions.

2.The role of ordinary bicycles:

(1) Ordinary bicycles can travel and are the most environmentally friendly way of travel. And to create a cycling environment for everyone.

(2) Riding a bicycle often can also exercise and improve immunity. It is also a way to exercise.

3.The role of bicycles for fitness:

(1) It can prevent brain aging and improve the agility of the nervous system. Modern sports medicine research results show that cycling is a heterolateral dominance exercise. Alternate pedaling of the two legs can develop the left and right brain functions at the same time to prevent premature aging and partial failure.

(2) It can improve cardiopulmonary function, exercise lower limb muscle strength and enhance overall endurance. The endurance exercise effect of exercise on internal organs is the same as swimming and running. This exercise not only benefits the 3 pairs of joints and 26 pairs of muscles in the lower limbs of the hip, knee, and ankle, but also the muscles of the neck, back, arms, abdomen, waist, groin, buttocks. The joints and ligaments are also exercised accordingly.

(3) Can lose weight. Due to the periodic aerobic exercise, the exerciser consumes more calories and can receive a significant weight loss effect.

(4) It can improve sexual function. Regular exercise can stimulate the secretion of estrogen or androgens in the human body, enhance sexual performance, and contribute to the harmony of sexual life between husband and wife.

(5) Longevity and longevity. According to the survey and statistics of relevant international committees, among the various professions in the world, postmen have the longest life span. One of the reasons is that they often ride bicycles when delivering letters.