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Electric bicycle shifting system

Electric bicycle shifting system

What is a transmission system?

To understand the electric bike  transmission, you must first understand the principle of the transmission system. The position where your feet are stepped on is called the crank, which drives the rotation of the large chainring, and transmits power through the chain to the flywheel, which is the chainring of the rear wheel, and then allows the electric  bicycle to move forward.

The transmission system includes a flywheel, a large plate, a front and rear transmission, a chain, and left and right integrated brake levers.

The appearance of the transmission drives the chain to reach different chainrings, and changes the pedaling gear ratio. Facing different terrains, you can choose the most suitable gear ratio, which not only saves energy, but also makes cycling more interesting.

Generally speaking, with a larger gear ratio, the front is large and the rear is small, the pedaling will be a little laborious, and can increase the speed; the smaller gear ratio, the front is small and the rear is large, the pedaling is relatively labor-saving, but the speed is slower.

Crankset 53/39, 52/36, 50/34 stupidly confused?

The  electric bike crank is the most overlooked and most important part. It is composed of two front chainrings.

Standard tough type (standard disc): (53) tooth outer ring and a smaller (39) tooth inner ring.

The second most common type of crank is a compact climbing type (compression disc). The use of a smaller inner ring (34 teeth) and the outer ring (50 teeth) greatly reduce the gear ratio, making it easier to climb steep slopes.

Of course, the two types are combined to develop the offensive and defensive type (semi-compressed disc), which uses a combination of (52 teeth) outer ring and (36 teeth) inner ring. Combining the advantages of both, it is a good choice for both uphill sprints.

Cassette flywheel

The size range of the flywheel is very wide. The most common 11-25 tooth combination is the favorite of professional riders. The tight gear ratio makes it easy to maintain a consistent pedal frequency. For some beginners, it may be more suitable for a slightly wider range of gear ratios, 11 or 12 to 27 or 28, so that it will be easier to climb. Of course, there is a wider flywheel gear ratio, which is 11-32 specially designed for mountain climbing, but it must be equipped with a long-legged rear derailleur to run smoothly.


Choose the same electric bike transmission brand and the number of flywheel gears (9, 10 or 11) to determine the chain. The more expensive the chain tends to be smoother, more durable, and lighter.

Front derailleur

The front derailleur is installed on the frame in two ways, the snap-type direct-lock type and the ring-type fixed type. The former is fixed with bolts and the latter is fastened with clamps. The front derailleur needs to be equipped with a double-disc or a three-disc crank, and then depends on the 9, 10 or 11-speed transmission system, because the narrower chain of the 11-speed system will affect the smoothness of the winding.

Rear derailleur

The rear derailleur needs to be purchased with a range of flywheel gear ratios. Generally divided into short, medium and long legs, the larger the gear ratio, the longer the legs are needed to move. When the leg length is selected, the 9, 10, or 11-speed transmission system of the system must be matched. Most rear derailleurs of different grades have the same mechanical structure and function. More expensive products are usually lighter and some will use carbon fiber. You can even consider electronic transmission systems.

Integrated brake lever

Road bikes use gearshift kits that integrate brakes and gearshifts. Each company has its own design and shifting methods. There are two major electric bike transmission companies on the market, Shimano from Japan and Sram from the United States. Two levers are designed in the STI brake lever-the rear small lever and the brake lever itself, which double as shifting. The SRAM system is called a double tie rod. The same lever is lightly pressed once to downshift, and heavy pressed once is upshift.

If you are interested in our electric bicycles, you can log on our official website to know more about details. If you have any query please feel free to contact us. We are looking forward to your arrival. www.zhsydz.com


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