1, early mountain bikes: the original mountain bikes usually only had single-speed or three-speed transmissions, and there was no special finger. The rider needs to shift gears by hand.

2. Stem fingering: In 1970s, stem fingering began to appear. This fingering controls the transmission by pulling the valve stem, which is more convenient and easy to use than picking.

3. Electronic fingering: In recent years, with the popularity of electric bicycles, electronic fingering has also begun to appear. This fingering can control the transmission through electronic signals, which can control the speed and resistance more accurately and automatically adjust to the best riding state.