Shimano SIS
The gear system in which the lever clicks into fixed positions, so each gear engages correctly at once.
Before SIS, the rider had to feel for the right lever position. Indexed shifting made it easy for everyone and became standard on almost all bicycles.
Materials: Aluminium, plastic and steel
Manufacture: Made in Sakai.
The lever that clicks between gears.
The derailleurs and cassette built to work together.