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I heard about variable speed bicycles? Who knows this?
Bicycle transmission system

The function of bicycle transmission system is to change the speed of the vehicle by changing the cooperation between the chain and different front and rear gear plates. The size of the front toothed disc and the size of the rear toothed disc determine the strength of the bicycle when turning the pedal. The bigger the front tooth plate is, the smaller the rear tooth plate is, and the harder it is to pedal. The smaller the front toothed disc is, the easier it is to tread when the rear toothed disc is bigger. According to the ability of different drivers, the speed of the bicycle can be adjusted by adjusting the size of the front and rear toothed discs, or to cope with different road sections and road conditions.

Chinese name

Bicycle transmission system

purpose

Change the speed of a bicycle.

Number of major parts

18, 2 1, 24, 27 30

algorithm

Number of teeth of front big plate x number of teeth of rear flywheel

creator

Paul de Vivi.

Tooth ratio

"Tooth ratio = the number of teeth in the front wheel/the number of teeth in the rear flywheel", basically, the function of the transmission system of bicycle gear and chain is to "convert the energy (horsepower) trampled by the driver into the torque of the tire".

Bicycle transmission system

"Speed" is determined by the maximum gear ratio (the maximum number of teeth on the front wheel corresponds to the minimum number of teeth on the rear flywheel). When the number of revolutions is the same, the greater the gear ratio, the faster the speed. For example, the maximum transmission ratio of a general 27-speed mountain climbing vehicle is "front 44T, rear 1 1T, and transmission ratio = 4". The driver will turn four times when stepping on a wheel, which is the fastest but the rim torque is the smallest. The opposite driver has to step on the wheel the most to maintain the torque needed for the car to move forward.

Tooth number reduction

In addition to the tooth ratio, another thing worth discussing is the decrease of the number of teeth. The often heard "close tooth ratio" means that the gap between teeth is small. Tooth number difference refers to the difference between the driver's output and the tire torque when shifting gears. If the difference is too large, it may suddenly become too heavy or too light, resulting in an uncertain number of laps. For the driver, it suddenly feels too important to exert oneself, and suddenly it feels too light. Both of these situations may hurt the knee and affect the control.

Bicycle transmission system

When the pedal rotates, the front toothed disc rotates, the force is transmitted to the rear toothed disc through the chain, and the wheel moves forward. The size (number of teeth) of the front toothed disc and the size (number of teeth) of the rear toothed disc determine the strength when turning the pedal.

The bigger the front toothed disc is, the smaller the rear toothed disc is, making it difficult to pedal (the distance that the bicycle moves forward becomes longer).

The smaller the front toothed disc is, the larger the rear toothed disc is, and it is easy to pedal (the distance that the bicycle moves forward becomes shorter).

Riding a bike means starting, stopping, uphill, downhill, windward and downwind. No matter under any conditions, you can keep a certain speed (bicycles can move forward quickly or slowly, and you can keep a certain pedaling speed and torque, so you need a gearbox.

You can't ride very fast without increasing your strength and only increasing the gear ratio. This was quickly discovered in the actual riding process. When riding by increasing the transmission ratio (high torque and low speed), the most suitable riding (combination of torque and speed that releases the most suitable energy) cannot be achieved. This will increase the burden on the knees and become the cause of various obstacles.