Why does exponential motion move on bicycles instead of traditional friction?

Because it is more practical and easy to use. In quite ancient times, such as the sixties and seventies, gear rods had smooth friction and symmetry in both directions. In one direction, it prevents the lever movement pulled by the cable tension. In the opposite direction, it just makes shifting more difficult. The movement is continuous and smooth, although it is a bit difficult. There is no "scale" or groove to tell you whether the equipment is working properly. You need to have a very keen sense to ensure that they work properly.

Under normal circumstances, the correct shift is to move the shift lever slightly out of the gear you want to engage, but not to the position where it engages with the next gear, then move the shift lever backwards a little and center the transmission with the sprocket. The front drive is easier, because usually you only have two links, and the only preventive measure is to ensure that one side of the drive will not rub the chain.

This requires considerable training to operate this type of transmitter accurately and quickly, and professionals will make mistakes in a hurry. What makes this system even more impractical is that on most bicycles, the lever is installed on the lower tube, and people have to reach out their hands to reach it.

Then in the late 1970s, when I was not too old, the "anti-friction" gear shifter appeared. I think they were invented by Santo, but they were immediately copied by Shimano. For several years, Campagnolo has been insisting on its simple and exquisite "standard friction" system.

The reverse friction only acts on the tension of the cable, so it is not more difficult to move upward than to overcome the tension. In santur's system, you have a "ratchet wheel", which makes a slight click instead of rubbing the gear. Not every gear makes a clear click sound, but a frequent "click" sound, indicating the progress of gear shifting.

If you have a pair of good ears, you can easily calculate how many beats are needed for gear meshing, and the gear shifting action will be more accurate and easier to complete. Usually these levers are used to put down one end of the iron bar, which is easier to reach than the levers on the pipeline below. Both cyclists and cyclists like it. Their only drawback is that when you stand on the pedal, you may shift gears with your knees. This is why the high jump stick in cycling and traveling has limbs stretching. Nowadays, people can buy some chocolate bars; In the past, people often used car jacks to pull down one end of ordinary road racing cars.

But all this was broken by the invention of SIS "Shimano Index System", which is the greatest revolution of bicycle machinery in 50 years. In this system, you just need to move the joystick (or handle) until you feel a clear "click" sound, and then the gears mesh perfectly. There is no need to look back, no need for fine adjustment, no need for musicians' ears and surgeons' touch to know whether the gears are properly engaged.

In this way, multi-speed transmission is no longer the patent of experts, but everyone can do it. Where are the experts? Have they benefited from the exponential transfer? Your bet. The indexing movement allows the integration of the moving lever and the racing handlebar on the brake lever. Now shifting gears is as easy as braking. You can change gears when braking. This was not possible in the previous system.

In addition, due to the higher movement accuracy, the spacing between adjacent sprockets can be reduced, and more gears can be installed in the rear gear: the maximum number of gears with friction bars is 7; Today, as the index changes, we are at 12, and it is still growing.