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  1. #1
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    Zero Tension on NDS Spoke after ride

    The wheel: Pacenti SL23, King r45, Cxrays 24 count.

    The good news? the wheel was still in true enough to complete the 20-30 miles I had left after I noticed something was wrong.

    The bad news? Well, I guess I don't have enough tension on the NDS.

    I've already put 500 miles (probably closer to 1000) on these wheels.

    The question is how to go about fixing the problem? My inclination is to remove the tire/tube, remove all the tension from the spokes, and bring them up to tension again. I brought all the DS spokes up to around 125 Kgf when I built it, although, some may have been a little less because I was a little nervous having some of the spokes go over 130. The Park Tensiometer reading for 130 Kgf is 15 for CX-Rays. Although I try to keep the tensions even there are some that have more/less with the truing. Do I bring the spoke with the least tension up to a Kgf of 125 or 130?

    Thanks in advance.

  2. #2
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    Quote Originally Posted by VinPaysDoc View Post
    My inclination is to remove the tire/tube, remove all the tension from the spokes, and bring them up to tension again.
    Good idea and while you're at it replace the DS CX-Rays with Sapim Race or even Sapim Strong.

  3. #3
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    How are the wheels laced? 2x/2x?
    2012 Cervelo S5 Team
    2012 Felt Z6 (sold)

  4. #4
    Online Wheel Builder
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    Did you use any sort of spoke prep?

  5. #5
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    2x/2x

  6. #6
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    Yes. I used the Wheelsmith spoke prep. I think I may have misread the tensiometer the first truing. I just got finished bringing all the DS spokes up to 125-130 Kgf. Most of the NDS spokes are now around 55-60 Kgf.

  7. #7
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    Zero Tension on NDS Spoke after ride

    Quote Originally Posted by VinPaysDoc View Post
    The wheel: Pacenti SL23, King r45, Cxrays 24 count.

    The question is how to go about fixing the problem? My inclination is to remove the tire/tube, remove all the tension from the spokes, and bring them up to tension again. I brought all the DS spokes up to around 125 Kgf when I built it, although, some may have been a little less because I was a little nervous having some of the spokes go over 130. The Park Tensiometer reading for 130 Kgf is 15 for CX-Rays. Although I try to keep the tensions even there are some that have more/less with the truing. Do I bring the spoke with the least tension up to a Kgf of 125 or 130?

    Thanks in advance.
    The anticipated Tnds on your rear wheel is around 57 to 59kgf, depending on choice of crosses, when the Tds is 125 kgf. That much tension should be adequate if the number and type of spokes are adequate for your weight, if the tension is equal on each side and if all the wind up is taken out.

    Hopefully there was some wind up left and when you went over a bump? It got released.

    I would not bring the spoke with the least tension up to 125 or 130 indiscriminately because this will knock the wheel out of true. I 'm assuming the wheel is true now.
    I would detention/stress relief/tension/relief and repeat tension/relief until tension is uniform on the DS side and the wheel is true.
    Incidentally, what you read as 125 kgf on your Park is not necessarily accurate. Most probably it is not. I use my Park more to check relative tension rather than absolute.

  8. #8
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    What I meant was that I would bring all the spokes up to tension but stop when the spoke with the least tension was up to 125. I think what happened here is that I read the Park Tensiometer wrong when I built the wheel. I didn't achieve enough tension in the DS spokes to allow the NDS to have a chance. The spoke tension on the DS is now even at around 130 Kgf (Park Tensiometer 15). The wheel is true and has been stress relieved. All of the Tnds tensions are 50+ now.

    I checked my front wheel and the Tensions are even around 80 Kgf. It's looking like a problem with my conversion on the meter. What tension should the front spokes be at?

    Thanks for the assist.

  9. #9
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    Zero Tension on NDS Spoke after ride

    Front wheel I typically do around 100kgf. Others have gone down to 90 kgf without problems.

  10. #10
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    Thanks. I'll bring the tension up on the front as well.

  11. #11
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    Take a look at the tensions and true of the wheel once you air up the tire, rear wheels will move off center once the tire is put under pressure.

  12. #12
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    I will say it was a lot easier getting the tire on the rim this time. It helps knowing to keep the beads in the center to make room to get the final part of the bead on.

  13. #13
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    Quote Originally Posted by dcgriz View Post
    ...if the number and type of spokes are adequate for your weight,
    Is there any math formula that calculates the number of spokes as a function of rider's weight and spoke strength (or geometric dimensions)?

  14. #14
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    Zero Tension on NDS Spoke after ride

    Quote Originally Posted by CAADEL View Post
    Is there any math formula that calculates the number of spokes as a function of rider's weight and spoke strength (or geometric dimensions)?
    I've read papers showing not a single equation but a network of equations addressing the issue in a static approach. However, I don't believe such approach is adequate because it does not determine durability as a function of time and conditions of use.

    I understand that The Finite Element Method computer analysis is used to most accurately model deflections within the wheel structure, but I have no experience with it.

  15. #15
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    Quote Originally Posted by dcgriz View Post
    I've read papers showing not a single equation but a network of equations addressing the issue in a static approach. However, I don't believe such approach is adequate because it does not determine durability as a function of time and conditions of use.

    I understand that The Finite Element Method computer analysis is used to most accurately model deflections within the wheel structure, but I have no experience with it.
    FEM would work but it would require a number of assumptions and safety factors. Those assumptions and safety factors would dominate the result so really it would be a bogus calculation, no better than the gut feel and rules of thumb that wheel builders have accumulated over the years.

  16. #16
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    Zero Tension on NDS Spoke after ride

    Quote Originally Posted by Kerry Irons View Post
    FEM would work but it would require a number of assumptions and safety factors. Those assumptions and safety factors would dominate the result so really it would be a bogus calculation, no better than the gut feel and rules of thumb that wheel builders have accumulated over the years.
    I use modeling (not FEM) to predict system behavior in my line of work so I understand your point about over designing.

    I'm assuming the major wheel manufactures follow a similar process when they build a wheel prone to performance (win a race?) at the expense of durability.

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