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Version vom 13. November 2019, 09:46 Uhr
, 13. November 2019→Sturmey-Archer Achtgang: Bild
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The Sturmey-Archer 8-speed hub has three simple planetary systems, each with a different increase ratio. The hub achieves 8 speeds by using 1, 2 or all 3 of the planetary systems in series, or bypassing them all for the unity ratio. Consequently, the lowest gear is most efficient, and the top gear, which uses all three planetary systems, least efficient. On a conventional bicycle, this hub must use an unusually-large sprocket and a small chainwheel, but on the other hand, this hub is especially well-suited to a bicycle with small wheels. | The Sturmey-Archer 8-speed hub has three simple planetary systems, each with a different increase ratio. The hub achieves 8 speeds by using 1, 2 or all 3 of the planetary systems in series, or bypassing them all for the unity ratio. Consequently, the lowest gear is most efficient, and the top gear, which uses all three planetary systems, least efficient. On a conventional bicycle, this hub must use an unusually-large sprocket and a small chainwheel, but on the other hand, this hub is especially well-suited to a bicycle with small wheels. | ||
Sturmey-Archer X-RD8(W) | <center>''Schnittmodell einer Sturmey-Archer X-RD8(W) Acht-Gang-Nabe mit drei Gangabstufungen (rechts nach links in der Illustration) '' | ||
[[Datei:Xrd8w.jpg|center|Schnittmodell einer Sturmey-Archer X-RD8(W) Acht-Gang-Nabe mit drei Gangabstufungen (rechts nach links in der Illustration)]] | |||
</center> | |||
The first model of this hub offered had a total range of 3.05. The current (2010) version has a total range of 3.24, and steps of approximately 14% except for the outermost steps of 30%. A second-lowest ratio closer to unity would require a small sun gear that would reduce reliability of the hub. Shifting is by locking none, 1, 2 or all 3 of the sun gears to the axle. When a sun gear is unlocked, the stage operates at unity ratio. When a sun gear is locked to the axle, the stage gears up, overriding the pawls used for the unity ratio. There is no "neutral" gear, as the hub defaults to the next lower gear. This hub uses a rotary shifter-cable attachment inside the right-side dropout. | |||
==Rückhaltloser Aufbau: Sachs Elan und Rohloff Speedhub== | ==Rückhaltloser Aufbau: Sachs Elan und Rohloff Speedhub== | ||