Велосипеды с планетарной втулкой

Planetary gear hub

— the planetary gear hub is used in the rear wheel of a bicycle; its name comes from the shift mechanism mounted right inside the hub. Such a mechanism has several advantages over the classic design with several sprockets, between which the chain is thrown. Firstly, it is noticeably more compact, and one sprocket is enough for the rear wheel. Secondly, all mechanics are hidden inside the hub, protected from contamination and require virtually no maintenance. Thirdly, planetary hubs can be used with any type of brake, including coaster ones. On the other hand, such a switching mechanism is more complicated and more expensive than the classic one, and the number of speeds provided by it rarely exceeds 3. Therefore, the planetary gear hub is used mainly in urban bikes, which do not require numerous gears.