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I asked a question recently about replacing a cracked front hub on a vintage steel wheel (How to replace a broken front hub on a vintage steel wheel from a vintage steel bike?)

Thanks for all the useful answers.

This is related, but a different question.

I noticed that the dimensions of the standard hub seemed to be very similar to the dimensions of a dynamo hub (all sturmey archer). Since the dynamo hub costs just a few Euro more than the standard hub, it might be nice to add a hub dynamo while I'm at it.

The dimensions aren't EXACTLY the same, but they're similar. Are the dimensions critical?

I'm not even sure I'm reading the specs right...

The standard hub is this [this] (https://www.sturmey-archer.com/files/catalog/files/274/SPECIFICATIONS%20-%20HBT%20HUBS.pdf)

The dynamo is [this] (https://www.sturmey-archer.com/files/catalog/files/166/SPECIFICATIONS%20-%20DYNOHUB.pdf)

Would it work to replace the broken standard hub with a dynamo hub, or would the spokes all end up with the wrong angles/lenghts/whatever? I can always just buy the standard hub, which is dimensionally the same as what's on the wheel now.

H

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    You might want to read this previous discussion on the importance of spoke length. Spokes are not all that expensive if you do need to replace them. Also, just to be explicit, the old and new hub need to have the same spoke counts.
    – Adam Rice
    Dec 20, 2021 at 15:26
  • Thanks. Getting the same spoke count isn't a problem. 36 on both. It's just the spoke length and the (slight) difference in diameters of the hubs that worries me.
    – HSH
    Dec 21, 2021 at 15:36

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If the wheel is laced cross three (the each spoke crosses three spokes between hub and rim) and you are willing to rebuild the wheel or pay someone do it, it is possible.

The spoke length does need to be correct or very close. For 3x laced wheels changing to a different sized hub is often possible, because the spoke leaves the hub almost tangentially so a change in hub diameter translates to much smaller change in spoke length. In this case the 5mm diameter translates to 1mm change in spoke length, which should work.

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  • Thanks. Spoke patterns are new to me! Each spoke crosses two others between hub and rim. The spokes leave at about 45 degrees to the hub. I had misread the specs and thought the diameter/radius difference was less than you'e indicating. If I'm reading it right then the diameters (to the center of the spoke holes) is 66mm vs 61.5mm....so 4.5 or rounded to 5. Which would make it hard to tension the spokes, I guess...with the dynamohub being a little too big.
    – HSH
    Dec 21, 2021 at 15:51

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