Question on spoke tension

Dan O writes:

If you tighten a spoke, the ~directly opposite spoke will
tighten ~equally.

Only true for a theoretical wheel with two spokes.

Note, by the way, that unless the wheel is radially spoked, the directly
opposite spoke on the same flange is not pointing in the same direction.
Any symmetry arguments, which don't work with a radial spoking when
closely examined, don't make sense with a non-radial spoking.


--
Joe Riel

Ralph ?

AE6KS -

same and opposite directions ? E=IX ?

what ?

over in Yak Yak posters describe paddle movements...get back Dude !

resulting in an increase in tension to the spokes
radiating from the hub in the opposite direction

gnaw....my englaze sez the opposite. tighten 6 adjacent with reducktion to the ends and the opposites reduce in tension...otherwise the universe is collapsing.

Brandt coached me on the math approach wheel as curved bridge truss. All angles and pressures, as applicable, are equal. In proceeding to true, follow that path.

rotates in the opposite direction ? opposite of what ? counterclockwise nipple movement ?

On Monday, June 9, 2014 11:11:03 AM UTC-7, JoeRiel wrote:
Dan O writes:



If you tighten a spoke, the ~directly opposite spoke will

tighten ~equally.



Only true for a theoretical wheel with two spokes.



Note, by the way, that unless the wheel is radially spoked, the directly

opposite spoke on the same flange is not pointing in the same direction.

Any symmetry arguments, which don't work with a radial spoking when

closely examined, don't make sense with a non-radial spoking.


hence the '~'

Dan O writes:

On Monday, June 9, 2014 11:11:03 AM UTC-7, JoeRiel wrote:
Dan O writes:



If you tighten a spoke, the ~directly opposite spoke will

tighten ~equally.



Only true for a theoretical wheel with two spokes.



Note, by the way, that unless the wheel is radially spoked, the directly

opposite spoke on the same flange is not pointing in the same direction.

Any symmetry arguments, which don't work with a radial spoking when

closely examined, don't make sense with a non-radial spoking.


hence the '~'

Only if ~ is considered negation.

--
Joe Riel

Jeff Liebermann wrote:
On Mon, 09 Jun 2014 04:13:12 GMT, Ralph Barone
wrote:

A quick question here. In a 3-cross lacing pattern, every spoke touches one
other spoke (at the third cross). Thinking through the mechanics of the
situation, it would appear to me that if both spokes are initially at the
same tension and you make a minor tweak (loosen or tighten) to one spoke,
that the change in tension will end up distributed nearly evenly across
both spokes. Is this correct?

Nope. As I understand it, if you tighten one spoke, you change both
the spoke tension and apply rotational tension (torque) to the hub.
The hub will try to rotate very slightly in the direction of the
increased tension, resulting in an increase in tension to the spokes
radiating from the hub in the opposite direction. There will
simulaneously be a decrease in tension in the spokes going the same
direction as the tighened spoke. The tension in all the spokes in one
direction MUST equal the tension in all the spokes going in the other
direction. Tighten one spoke, and they all change tension.

You can verify this effect by measuring the pitch of the spokes when
plucked. I haven't tried either of these:
https://itunes.apple.com/us/app/spoke-tension-gauge/id518870820?mt=8
https://play.google.com/store/apps/details?id=jp.gr.java_conf.MagokoroStudio.checkspo ke
Change tension on ANY spoke, pluck any other spoke, and you should
hear (or see) a slight change in pitch.



Jeff, I agree with your analysis if none of the spokes touch. However, if
two spokes cross over, then they exert a force on each other which should
be equal to their tension times the sine of the break angle. Now since the
crossing point isn't accelerating, we can say that T1*sin(a1) = T2*sin(a2).
If we reduce the tension in spoke 1, its break angle should increase and
spoke 2's break angle should decrease. This will result in a lengthening
of spoke 1 and a shortening of spoke 2. For small changes in tension, the
break angles should remain essentially constant, which leads me to the
conclusion that both spokes share the tension change equally.

On Mon, 09 Jun 2014 04:13:12 GMT, Ralph Barone
wrote:
A quick question here. In a 3-cross lacing pattern, every spoke
touches one other spoke (at the third cross). Thinking through the
mechanics of the situation, it would appear to me that if both spokes
are initially at the same tension and you make a minor tweak (loosen
or tighten) to one spoke, that the change in tension will end up
distributed nearly evenly across both spokes. Is this correct?

No. Think about the geometries involved. Some change in the crossing
spoke happens but not much. With a tensiometer or even just by plucking
the spokes you can get a good sense of this.

On Monday, June 9, 2014 4:32:59 PM UTC-7, JoeRiel wrote:
Dan O writes:



On Monday, June 9, 2014 11:11:03 AM UTC-7, JoeRiel wrote:

Dan O writes:







If you tighten a spoke, the ~directly opposite spoke will



tighten ~equally.







Only true for a theoretical wheel with two spokes.







Note, by the way, that unless the wheel is radially spoked, the directly



opposite spoke on the same flange is not pointing in the same direction.



Any symmetry arguments, which don't work with a radial spoking when



closely examined, don't make sense with a non-radial spoking.





hence the '~'



Only if ~ is considered negation.


What?? I'm pretty sure that I said what Jeff said before he
said it but just maybe not as "technically".

In any case, I qualified everything heavily as oversimplification
and uneducated sense and not spot on but surely closer than
rubbing somehow imparts tension or that the tension change is
no different in any of the other spokes on that side of the
wheel (they're ~all different, aren't they? - except for those
180 degrees apart) and in the end doesn't matter anyway just
"I'm a veg, Danny. Be the ball" and in any any case my wheels
have somehow grown strong and ~true after many, many hours of
our communion over a spoke wrench.

On Monday, June 9, 2014 7:40:03 PM UTC-7, Dan O wrote:
On Monday, June 9, 2014 4:32:59 PM UTC-7, JoeRiel wrote:
Dan O writes:
On Monday, June 9, 2014 11:11:03 AM UTC-7, JoeRiel wrote:
Dan O writes:

If you tighten a spoke, the ~directly opposite spoke will
tighten ~equally.

Only true for a theoretical wheel with two spokes.

Note, by the way, that unless the wheel is radially spoked, the directly
opposite spoke on the same flange is not pointing in the same direction.

Any symmetry arguments, which don't work with a radial spoking when
closely examined, don't make sense with a non-radial spoking.

hence the '~'

Only if ~ is considered negation.

I meant the tilde to mean approximation, and only that relatively.

ISTM that tightening one spoke reduces tension on other spokes
working to hold the rim and hub together in that same direction
(takes a load off), and increases tension on other spokes holding
the rim and hub together in the opposite direction (works against
them), and the amount of increase or decrease varies with angle
away from the vector where the change is externally applied.

That's only one side of the hub (~two dimensions), and assumes
a round wheel. There is interplay in the third dimension
involving the spokes on the other side.

I have not read The Bicycle Wheel. I might like to, but won't
get around to everything I might like to do, and as noted earlier
seem to be coming along ~nicely without it so far - at least my
wheels work and hold up remarkably well.

After some attempts to true wheels early in life that made things
worse, I was afraid to touch them until several years ago when I
gave it another shot. Since then I have had times when it seemed
like I just wasn't getting it. But I think I sort of have a handle
on it now - at least for the 3-cross 36-spoke wheels on my bikes.

I have started reading a little Feynman on physics. I've been
very interested and curious about quantum physics for a long
time. I suspect learning more about that might enhance my
relationship with my bicycle wheels. There could be a broad
philosophical breakthrough ahead.

Is that what this is? Philosophy?

Dan O writes:

On Monday, June 9, 2014 7:40:03 PM UTC-7, Dan O wrote:
On Monday, June 9, 2014 4:32:59 PM UTC-7, JoeRiel wrote:
Dan O writes:
On Monday, June 9, 2014 11:11:03 AM UTC-7, JoeRiel wrote:
Dan O writes:

If you tighten a spoke, the ~directly opposite spoke will
tighten ~equally.

Only true for a theoretical wheel with two spokes.

Note, by the way, that unless the wheel is radially spoked, the directly
opposite spoke on the same flange is not pointing in the same direction.

Any symmetry arguments, which don't work with a radial spoking when
closely examined, don't make sense with a non-radial spoking.

hence the '~'

Only if ~ is considered negation.

I meant the tilde to mean approximation, and only that relatively.

It's not a good approximation. Sorry, I'd answer in length
but my left wrist is rebeling, need to reduce the keyboarding
for a while.


--
Joe Riel