This question is just one of curiosity. I have a hard time visualizing this. How do internal hubs work? Does anyone have a cross cut image that is easy to understand?

  • 1
    Hard to answer as there are a half-dozen different schemes. However, I'm sure there are a few "exploded views" on the web somewhere. May 24 '15 at 11:56
  • Do you mean how do they work-as-reduction-gears or how-do-they-shift-between-gears? The two are similar but different.
    – RoboKaren
    May 25 '15 at 3:38
  • Thanks for edit @RoboKaren. I was just getting back to it!
    – andy256
    May 25 '15 at 3:55

The only scheme I know of is called planetary gears, or as Wikipedia calls it Epicyclic gearing. @Daniel suggests that there are other designs.

Here is one of the images from Wikipedia:

Planetary gears

The inner gear is called the sun and the gears that go around that are called the planetary gears. In the basic design (the original Sturmey Archer design) the sun was fixed to the axle, and the pedals could either drive the assembly that the planets are on, or the outer ring. The wheel could be driven by the outer ring or the planetary assembly. A moving selector device controls the mechanism. The gear ratios were 1:2/3, 1:1, 1:3/2.

Sturmey Archer 3-gear classic hub

Thanks to @RoboKaren for editing in the image.

For more details, see the Wikipedia Sturmey Archer page, the Rohloff Speedhub page, and the Hub gear page.

  • Oh, how I remember as a teenager, discovering all those bearings, springs, ratchets and pawls! It was the little selector with the four lugs that always needed replacing.
    – andy256
    May 25 '15 at 4:09

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