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Lace the hub first: Fast wheel building

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  • #61
    You don't have to cross the spokes. My intuition says crossing them would increase the lateral stiffness of the wheel, but I'm not sure by how much. I don't think it is a good practice to bend spokes, but I've seen mechanics replace spokes by bending them in a circle to install them. I would think that a significantly stressed spoke would have worse repercussions down the road than not interlacing them (but I don't have any proof of the bent spokes breaking or coming out of true later more often.) If you can handle all the spokes flopping around and you can keep them sorted, dropping them all at once and crossing them in pairs or 4s, then you can avoid bending them. I think plenty of people have used Sheldon's method of lacing all the trailing spokes then interweaving the leading spokes (which makes slightly bending spokes unavoidable) and wheels have stayed true and lasted a long time, though, if you can avoid such bending, then it probably is ideal.

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    • #62
      Yes, the outside spokes should cross under the inside spoke

      I'm very happy that after all of this time this thread has still provided a good discussion on wheel building. As always, my response to the current topic is from my own experience, and not meant to step on anyones toes.

      First of all, I want to point out that this is for traditional flanged hubs that use J-Bend spokes (like every unicycle hub that I have ever seen).

      There are good arguments to be made either way about lateral stiffness, but overall wheel reliability will be better if you cross the inside spokes over the outside spokes where they meet closest to the rim.

      There are many factors that make a good wheel build, and many of them are decisions with tradeoffs depending on the needs of the rider for the particular wheel. At the same time there are certain things that all well built wheels should have in common. Probably second only to even tension, the "set" of the spokes aligns the spokes from the hub to the rim in the most direct path.

      The inside spokes don't need any help because they describe a perfect line from the hub to the rim, but the outside spokes point away from the rim. When building it is important to physically set the spokes to point more or less to the rim, and I do this by gently hammering on the spoke at the flange to set the angle. Even with the new angle set into the spoke it still doesn't perfectly achieve the desired result, and crossing under an inside spoke finishes the job.

      Why is this going to build a more reliable wheel? Because spoke movement causes fatigue in the bend, and ultimately leads to broken spokes. The movement is initiated by the cyclic loading of the wheel, but if the spoke is positioned well, and held tightly in the flange by the pressure from the crossing spoke it won't move.

      Wheels without interwoven spokes?

      The only time I don't build wheels with interwoven spokes is when the hub is not of a traditional design. There are plenty of hubs that are designed to create a perfect spoke path for every spoke, and these hubs shouldn't be crossed in the manner described above. Every decent factory built wheel that I have worked on with spokes that don't interweave has had a hub like this. Many use straight pull spokes, but some use J-Bend spokes.

      Jerry
      "A properly ridden unicycle is like an object in orbit: constantly falling but never landing." -Diogenes

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      • #63
        Unearthing this thread...

        Mad4One just published their own recommandations for wheel building. That's very generous of them. I didn't know they're lacing each wheel in their italian workshop - hence the options they offer, and the fact that they do 4 crosses on larger wheels.

        Here it is:
        http://unaruota.com/ZC/index.php?mai...a3&language=en

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        • #64
          The instructions seem pretty similar to the Sheldon Brown page, only with a little less detail.

          I'm not exactly sure why they are recommending 4x for larger wheels; although it's usually not a problem. 4x used to be pretty common on touring bikes, and tandems, but fell out of use as small hub flanges became popular.

          Probably the biggest problem is that as the spoke holes get closer together it becomes likely to have a spoke pass over the head of the first spoke it crosses. Since the spoke "set" is critical to a strong wheel this adds an additional factor in getting a good straight path from the hub to the rim.

          Large flange hubs have more space between spoke holes, and so there is more room for spokes that are at a true tangent to the flange.

          As for strength, I'm not sure that more crosses equals a significantly stronger wheel. I will say that the strongest wheel has the spokes leaving the hub at a true tangent, and that on a 36 hole hub that would be 4x. It's all compromise though, and I would not do 4x if it meant crossing a spoke head.

          The value of 4x for loaded bikes is that the spokes are longer. Longer spokes under the same tension have more potential elongation (stretch), and a better ability to go through cyclic loading without putting slack into the spokes. Since broken spokes on loaded bikes (touring/tandems) are most frequently due to fatigue this extra elongation goes a long way towards mitigating the issue.

          It's possible that a rider on a single wheel could be putting the same kind of stress on the spokes, but I haven't seen enough broken spokes on unicycles to know if it is an issue.

          Aside from the extra stretch afforded to longer spokes I don't see much benefit for "strength" from using 4x.
          "A properly ridden unicycle is like an object in orbit: constantly falling but never landing." -Diogenes

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          • #65
            This video helped me. I found it very easy to follow.

            https://youtu.be/mIU6mi0K4Y4

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