Shimano Drei-Gang-Naben: Unterschied zwischen den Versionen

==Shimano Nexus Dreigang-Naben - aktuelle Produktion ab 2017: Oh - wow!==

The current (2017) generation of Shimano 3-speed internal-gear hubs is available with a coaster brake or with an optional external Rollerbrake or disc brake. The coaster brake is only suitable for flatland use: it will overheat on long downhill runs, like any coaster brake. The Rollerbrake also is somewhat prone to overheat, though the newer high-power model is less so, with its finned heat sink. The disc brake gets very hot but is made to withstand the heat. With any of these brakes, a front brake also should be installed -- see my article about braking and turning.

Various Nexus 3-speed models have overlocknut dimensions between 127 and 135 mm. These are listed for most hubs in the hub dimensions document linked below. It is usually possible to spread the rear triangle of a steel (Cromoly) frame to the needed width. Any good bicycle mechanic will be able to do this, or you can do it yourself. Most Shimano 3-speeds use a bellcrank and pushrod for shifting, rather than a pulley concentric with the axle. With these hubs, the orientation of the axle does not affect shifting, and oil lubrication is possible by removing the bellcrank and pushrod, then squirting oil into the hollow end of the axle.

Torque on the axle from the gear train is relatively low, and so the bellcrank-shifting hubs use only one non-turn washer, at the left side. The installation instructions specify a yellow washer, type 5R, for the coaster-brake version of the hub to place the axle with its round sides in the edges of the dropout slots. This is normally a right-side washer (so, the "R") but is shown on the left side in the documentation of this hub. A brown washer, Type 5L, is specified for the Rollerbrake version, also installed on the left side. As long as the round, threaded part of the axle contacts the faces of the dropouts so the axle sits straight, another Shimano anti-rotation washer could probably be substituted. The dropouts of an older three-speed bicycle will need to be widened to fit these hubs. File only the bottom of the slots, so you can be sure that the axle sits straight.