0 a type of bicycle gear that works by moving the bicycle chain from one sprocket wheel (= a wheel with a row of tooth-like parts) to another:
Its products ranged from suspension forks to derailleurs.
Shifter controls are mounted so that the right shifter controls the rear derailleur and the left shifter controls the front derailleur.
Meeting both these requirements is only possible if the rear derailleur is compatible with the gear range being used on the bike.
For example, a shaft-drive is usually accompanied by a hub gear, and derailleurs are usually implemented with chain drive.
These bicycles are without derailleur gears, hub gearing or other methods for varying the gear ratio of the bicycle.
Chains for small cogsets (e.g. seven-speeds) and other than derailleur-fitted bicycles are more tolerant of these master link dimensions.
This is the main reason that a single-speed bicycle can be more efficient than a derailleur geared bicycle.
A hub gear system provides greater ease-of-use and safety than a derailleur system, can provide a wide range of ratios, and requires little maintenance.
