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I have bought my first dynamo hub wheel with Shimano DH-3N72 hub.

The axle of the wheel fells like if it is over-tightened a bit, it rotates with feeling of clicks.

Should I loose the cones in the hub OR I am wrong and this is just magnetic forces inside a hub provide me such a feeling?

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    One test is to short the output pins and see if the notches get stronger but stay at the same spacing. Shorting makes the dynamo hard to turn (and you shouldn't ride the bike that way) – Móż Oct 7 '15 at 22:09
  • @Mσᶎ Wow, that's helpful! But couldn't it damage the hub? – constpetrov Oct 8 '15 at 6:51
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    Not for a little spin by hand, the dyno has to be designed to cope with accidental shorts. But ride it a few hundred kilometres that way and you might burn something out. I have shorted mine a few times while testing wiring without noticeable problems (mine is a SON, more than 50Mm old, I've had to replace the bearings once, and it still works fine) – Móż Oct 8 '15 at 10:16
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If the cones were over tightened you would likely feel two distinct notched, one finer one caused by over tightening the bearing cone and a coarser notch caused by the magnet/coil interaction. Because you only described one type of notch I would hazard a guess that it is the magnet/coil interaction, which is normal.

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    If you have cones handy, you might want to re-adjust them just to make sure. Most hubs are a little over-tightened anyway, once you consider the effect of the skewer. – BSO rider Oct 7 '15 at 13:19
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The feeling of notches is just the resistance you feel from moving the magnets past the coils in the hub. That's what generates the power. The hub is fine! When you actually ride the bike you won't feel a thing. Well, at least I don't feel anything. Some people have said they feel vibrations from their dynamo hub at lower speeds.

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