Hub gear
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A hub gear, internal-gear hub, internally geared hub or just gear hub is a gear ratio changing system commonly used on bicycles that is implemented with planetary or epicyclic gears. The gears and lub
Sturmey-Archer S3X
early NuVinci hub
NuVinci internals
A Sturmey-Archer AM bicycle hub gear mechanism with the ring gear removed to show the compound (stepped) planet gears.
Derailleur
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A derailleur is specifically a device that moves a bicycle chain from one sprocket to another, and more generally the entire gearset on a multiple-speed bicycle with such a mechanism.
Hub gear
…bicycles that is implemented with planetary or epicyclic gears. The gears and lubricants are sealed within the shell of the hub gear, in contrast with derailleur gears where the gears and mechanism are exposed to the elements. Changing the gear ratio was traditionally accomplished by a shift lever connected to the hub…
Shimano 600 front derailleur (1980)
Campagnolo Super Record rear derailleur (1983)
Shimano XT rear derailleur on a mountain bike
Pulley wheels for a rear derailleur