Re: (Un)even spoke tension

[Ted Bennett]

> I recently built a rear wheel where the eyelets deviate a bit. I'm not
> able to make this wheel true (<.25mm) with an even spoke tension.
>
> It's well known that even spoke tension is essential for a long
> lasting wheel. But I believe that even spoke tension is more important
> for some spokes than others. Please, comment on the following. I'm
> talking about a rear wheel, without disc brakes.
>
> If we divide the spokes into four categories we get:
>
> Drive side, pulling spokes
> Drive side, braking spokes
> Non-drive side, pulling spokes
> Non-drive side, braking spokes
>
> I believe that the hardest working spokes are the Drive side Pulling
> spokes. These spokes tighten up under high pedal force. Therefore
> these should share the load – even spoke tension.
>
> The Non-drive side spokes have less tension, 2/3 or so. The braking
> spokes will loosen up a bit under high pedal force. Therefore these
> spokes should also have even tension so none of them are looser than
> others, which could cause them to slack.
>
> Lastly we have the drive side braking spokes and the non-drive side
> pulling spokes.
>
> The Drive side braking spokes have a high tension under no load but
> loosen a bit under pedal force. Since they never get tighter I think
> some of these spokes can have a higher tension. A little looser may
> also be acceptable since they have a high tension at no load.
>
> The Non-drive side pulling spokes have approximately 2/3 the tension
> at no load. Some spokes can therefore be tightened a little more,
> maybe up to same tension as the drive side. They may also be able to
> have a little less tension since they never loosen under load.
>
> If you know about wheel building please comment on this.
>
> Thanks,
> Frank

A few points:

Unless the wheel in question has a hub brake, there are no "braking"
spokes as rim brakes apply no torque to the spokes or the hub.

Your statement that some spokes on the non-drive side can be safely
tightened up to the tension of the drive-side spokes is incorrect for
any dished wheel. To maintain the rim in the dished position, that is,
not centered between the hub flanges, the left side tension must always
be lower than the right side spokes.

The sentence "They[Non-drive side pulling spokes] may also be able to
have a little less tension since they never loosen under load." suggests
that you are unaware that decreased tension in the spokes under the hub
is what provides the upward force that supports the weight on the hub.
It is true that spoke tension must be high enough that they never
"loosen" but it's better to say that the tension never falls to zero.

Even and high tension, along with stress relief, are essential to a long
lasting and strong wheel. In any dished wheel, the tension is
necessarily unequal between the two sides.

--
Ted Bennett
Portland OR

[Werehatrack]

On 16 Jul 2003 21:34:39 -0700, (Frank) may have said:

>I recently built a rear wheel where the eyelets deviate a bit. I'm not
>able to make this wheel true (<.25mm) with an even spoke tension.

Perhaps this may provide some help:

http://www.sheldonbrown.com/wheelbuild.html

After reading that, I concluded that previously, I'd had no idea just
how little I really knew about the subject.

---
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pull WEEDS if replying via e-mail.

Yes, I have a killfile. If I don't respond to something,
it's also possible that I'm busy.

[Peter Cole]

"Frank" > wrote in message
m...
> I recently built a rear wheel where the eyelets deviate a bit. I'm not
> able to make this wheel true (<.25mm) with an even spoke tension.

If you really want to understand wheels and wheel building, buy Jobst Brandt's
book "The Bicycle Wheel".