Why don't bicycles use gearing?

The advantages of chain drive are: 1. Good fault tolerance, very low requirements for assembly accuracy, allowing front and rearSprocketsThere is not a small relative error; high transmission efficiency, does not require very high precision processing can reach more than 0.95, while the two-stage gear drive is generally about 0.8.

The advantage of gear drive is: can be closed structure to realize maintenance-free, better withstand the harsh environment of sun and rain.

Early in the development of bicycles engineering lions considered shaft drives. Let's start with the cost. The most expensive component of a bicycle in those days was thesprockets. There are over 400 parts that make up a chain. Chains are so expensive that all the parts on a car combined are not as expensive as a chain. Later, the standard of chain was standardized. This made it possible to automate the mass production of chains on a large scale. The cost thus fell to today's outrageous point. This made shaft drive lose its cost advantage. Riding experience, shaft drive has a big disadvantage is heavy. Anyone who has ridden a Mopar knows that. Reliability wise. Industrial products are always better developed the more they are used. Regarding chain drop and maintenance, it's actually a lot better than it used to be due to the widespread use of chain drives. Positive and negative tooth technology, chain guides, anti-drop discs, Teflon lubricants. To a large extent, they make up for the shortcomings of chain drives. Craftsmanship perspective. Chain drive can tolerate bike frame errors. It can work smoothly and reliably even if the toothpick and flywheel are not in a straight line. But it's a nightmare for shaft and belt drives. As for gearbox technology. Internal derailleurs are essentially very close to automobile transmissions. These transmissions have been around longer than the common external transmission. But it's expensive, heavy, and inefficiently driven.