Wheel trueness vs tension

Discussion in 'Cycling Equipment' started by Alan, Feb 24, 2003.

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  1. Alan

    Alan Guest

    I'm building a front wheel and have both sides more or less equal tension and laterally true as
    well. However I notice that the wheel is not perfectly round. To correct for roundness, I have to
    tighten some spokes in a few spots higher increasing the tension in those spokes. I'm not talking
    about huge differences but it does go from a reading of 60-65 to about 70 on my tensiometer.

    So what's more preferable? Perfectly round wheel or a evenly tensioned wheel? I'm unlikely to detect
    a non-perfectly round wheel. Would an evenly tensioned wheel in this case be more desirable since it
    equals a stronger wheel?

    alan
     
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  2. Wheel truing sometimes requires that spokes in some areas need to be loosened in order to make the
    wheel "round" Lateral is the easy part so that is will be done later in the tension process. First
    get dish as close as possible Second do the up and down (round part) Third step is lateral Fourth,
    recheck the dish Fifth, final tension. Turn all nipples 1/4 turn so tension comes up even. Check
    tension. Turn all nipples, anouther 1/4 turn if needed. And so on. This is what works for me. Happy
    cycling Speedy

    Alan wrote:

    > I'm building a front wheel and have both sides more or less equal tension and laterally true as
    > well. However I notice that the wheel is not perfectly round. To correct for roundness, I have to
    > tighten some spokes in a few spots higher increasing the tension in those spokes. I'm not talking
    > about huge differences but it does go from a reading of 60-65 to about 70 on my tensiometer.
    >
    > So what's more preferable? Perfectly round wheel or a evenly tensioned wheel? I'm unlikely to
    > detect a non-perfectly round wheel. Would an evenly tensioned wheel in this case be more desirable
    > since it equals a stronger wheel?
    >
    > alan

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  3. Coppi

    Coppi Guest

    You will [most likely] never have a wheel with matching spoke tension on every spoke. Defiantly go
    for the round wheel - also, try not to rely on a spoke tension meter. I don't think they are useful
    unless you are building something unique that requires accurate spoke tension like carbon rims or
    paired spokes... T

    "Alan" <[email protected]> wrote in message news:[email protected]...
    > I'm building a front wheel and have both sides more or less equal tension and laterally true as
    > well. However I notice that the wheel is not perfectly round. To correct for roundness, I have to
    > tighten some spokes in a few spots higher increasing the tension in those spokes. I'm not talking
    > about huge differences but it does go from a reading of 60-65 to about 70 on my tensiometer.
    >
    > So what's more preferable? Perfectly round wheel or a evenly tensioned wheel? I'm unlikely to
    > detect a non-perfectly round wheel. Would an evenly tensioned wheel in this case be more desirable
    > since it equals a stronger wheel?
    >
    > alan
     
  4. Jobst Brandt

    Jobst Brandt Guest

    Alan who? writes:

    > I'm building a front wheel and have both sides more or less equal tension and laterally true as
    > well. However I notice that the wheel is not perfectly round. To correct for roundness, I have to
    > tighten some spokes in a few spots higher increasing the tension in those spokes. I'm not talking
    > about huge differences but it does go from a reading of 60-65 to about 70 on my tensiometer.

    > So what's more preferable? Perfectly round wheel or a evenly tensioned wheel? I'm unlikely to
    > detect a non-perfectly round wheel. Would an evenly tensioned wheel in this case be more desirable
    > since it equals a stronger wheel?

    Unless there is a discontinuity at the rim joint, I think you'll get uniform high tension if you
    get tighten the spokes a bit more. Rim ovality is a wimpy force compared to spoke tension. There
    are two reasons why people build loose wheels. The rim is true when new and tightening the spokes
    to proper tension requires this to be done uniformly. A lightly tensioned wheel will often maintain
    its original trueness if not made tight. The other is a misunderstanding of the relationship
    between wheel strength and tension... and that tension is essential to make a durable wheel. That
    is why so many wheel builders reach for some sort of spoke glue so their loosely spoked wheels will
    not unscrew.

    True that wheel and get it tight enough.

    Jobst Brandt [email protected] Palo Alto CA
     
  5. Xyz

    Xyz Guest

    On Mon, 24 Feb 2003 13:43:07 -0800, "S. Delaire \"Rotatorrecumbent\"" <[email protected]> wrote:

    >Wheel truing sometimes requires that spokes in some areas need to be loosened in order to make the
    >wheel "round"
    This is what I have done for many years (not much over the past few years) when truing my own (and
    friends) wheels. I prefer to have a round wheel even at the expense of some spokes not being all the
    same tension (as long as they're not too loose obviously). I have never used a spoke tension meter,
    just by feel. I like stressing the rim (applying some pressure from either side) two or so times
    during a big truing procedure. I like to true my own wheels and can feel more confident about the
    job than if I took it to a local bike store (which may have many wheels to true and not give yours
    the attention to detail as you would).

    >Lateral is the easy part so that is will be done later in the tension process. First get dish as
    >close as possible Second do the up and down (round part) Third step is lateral Fourth, recheck
    >the dish Fifth, final tension. Turn all nipples 1/4 turn so tension comes up even. Check tension.
    >Turn all nipples, anouther 1/4 turn if needed. And so on. This is what works for me. Happy
    >cycling Speedy
    >
    >
    >
    >Alan wrote:
    >
    >> I'm building a front wheel and have both sides more or less equal tension and laterally true as
    >> well. However I notice that the wheel is not perfectly round. To correct for roundness, I have to
    >> tighten some spokes in a few spots higher increasing the tension in those spokes. I'm not talking
    >> about huge differences but it does go from a reading of 60-65 to about 70 on my tensiometer.
    >>
    >> So what's more preferable? Perfectly round wheel or a evenly tensioned wheel? I'm unlikely to
    >> detect a non-perfectly round wheel. Would an evenly tensioned wheel in this case be more
    >> desirable since it equals a stronger wheel?
    >>
    >> alan
    >
    >
    >
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  6. David Ornee

    David Ornee Guest

    "Alan" <[email protected]> wrote in message news:[email protected]...
    > I'm building a front wheel and have both sides more or less equal tension and laterally true as
    > well. However I notice that the wheel is not perfectly round. To correct for roundness, I have to
    > tighten some spokes in a few spots higher increasing the tension in those spokes. I'm not talking
    > about huge differences but it does go from a reading of 60-65 to about 70 on my tensiometer.
    >
    > So what's more preferable? Perfectly round wheel or a evenly tensioned wheel? I'm unlikely to
    > detect a non-perfectly round wheel. Would an evenly tensioned wheel in this case be more desirable
    > since it equals a stronger wheel?
    >
    > alan

    Correct and tension balance are more important than radial roundness. Barnett's chapter 17 says 10
    kgf balance is good enough. If you translate your "60-65 to about 70" to true kgf you will see how
    close you come to this objective. A properly tensioned and tensioned balanced wheel tends to stay
    true because the forces are balanced. Spokes share the load better when tensions are more precisely
    balanced. Of course you can find rims that won't allow you to achieve good tension balance. You may
    then choose to throw out the rim or put up with the imbalance. The process of tension balancing is
    a very worthwhile step. You can make a wheel true and have very unbalanced spoke tensions. The
    wheel won't act well under dynamic loads and will tend to loose true. If you have loose spokes,
    they may get looser. Spoke breakage and rim damage may occur as fatigue mechanisms work the
    materials involved.

    David Ornee, Western Springs, IL
     
  7. Alan

    Alan Guest

    > True that wheel and get it tight enough.
    >
    I guess that's the hard part, knowing when it's tight enough. I'm using DT 14/15 spokes so a
    tensiometer reading of 60 is 107 kgf and 70 is 143 kgf. I don't think 107 kgf would be considered
    too low and that's what I was aiming for without having to deal with too much spoke windup. 143 kgf
    seems possible so I will give that a try.

    Is too high tension when the wheel collapses?

    alan
     
  8. alan-<< I'm building a front wheel and have both sides more or less equal tension and laterally true
    as well. However I notice that the wheel is not perfectly round. To correct for roundness, I have to
    tighten some spokes in a few spots higher increasing the tension in those spokes. I'm not talking
    about huge differences but it does go from a reading of 60-65 to about 70 on my tensiometer.

    reduce the tension all around the rim, THEN do roundness and trueness, then raise the tension the
    same all around the wheel, when it is true and round., then check again.

    Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
    (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"
     
  9. Jay Beattie

    Jay Beattie Guest

    "Alan" <[email protected]> wrote in message news:[email protected]...
    > >
    > > True that wheel and get it tight enough.
    > >
    > I guess that's the hard part, knowing when it's tight enough. I'm using DT 14/15 spokes so a
    > tensiometer reading of 60 is 107 kgf and 70 is 143 kgf. I don't think 107 kgf would be considered
    > too low and that's what I was aiming for without having to deal with too much spoke windup. 143
    > kgf seems possible so I will give that a try.
    >
    > Is too high tension when the wheel collapses?

    Not quite. When the wheel is over-tensioned it develops a wave and cannot be made straight unless
    tension is reduced. This is mentioned in Jobst's book. Many times other problems develop including
    shearing-off nipple heads, galling nipple flats, popping spoke eyelets, etc. -- Jay Beattie.
     
  10. [email protected] (Alan) wrote in message news:<[email protected]>...
    > I'm building a front wheel and have both sides more or less equal tension and laterally true as
    > well. However I notice that the wheel is not perfectly round. To correct for roundness, I have to
    > tighten some spokes in a few spots higher increasing the tension in those spokes. I'm not talking
    > about huge differences but it does go from a reading of 60-65 to about 70 on my tensiometer.
    >
    > So what's more preferable? Perfectly round wheel or a evenly tensioned wheel? I'm unlikely to
    > detect a non-perfectly round wheel. Would an evenly tensioned wheel in this case be more desirable
    > since it equals a stronger wheel?
    >
    > alan

    I've never understood why absolute radial trueness is important. Clearly if the wheel is laterally
    out of true, if the dishing is wrong or if the spoke tension is uneven, these will affect
    performance. But 1mm out of round, say? I doubt there are many tyres that are uniform to within 1mm
    anyway, so what does a perfectly round rim get you?

    If I have to choose between perfect roundness and even spoke tension (some rims force that choice),
    then I would sacrifice roundness for even tension every time.

    Nigel Grinter
     
  11. Nigel Grinter <[email protected]> wrote:

    > [email protected] (Alan) wrote in message news:<[email protected]>...

    > I've never understood why absolute radial trueness is important. Clearly if the wheel is laterally
    > out of true, if the dishing is wrong or if the spoke tension is uneven, these will affect
    > performance. But 1mm out of round, say? I doubt there are many tyres that are uniform to within
    > 1mm anyway, so what does a perfectly round rim get you?

    > If I have to choose between perfect roundness and even spoke tension (some rims force that
    > choice), then I would sacrifice roundness for even tension every time.

    Also, to my experience, even with some quality rims achieving perfect roundness (within 0.5 mm or
    so) can be difficult. I've built a road wheelset using Mavic CXP-33 rims and an MTB wheelset using
    Mavic X-221 rims. The CXP-33's both had a fairly sharp flat spot at the weld, which was impossible
    to correct perfectly without extreme differences in tension. The X-221's weren't that bad, but the
    wheels also ended up having the most significant radial error where the rims were welded. Both sets
    of wheels are just fine in practice.

    -as
     
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