Spoke stress

Jobst Brandt wrote:

Over the years that I have been building wheels I have heard no
untwisting sounds because I use an over-shoot-and-back-off method to
adjust spokes. Readers of "the Bicycle Wheel" know how to do that as
well, it being mentioned in the book under "Spoke Twist".

I've used the over-shoot-and-back-off method of spoke adjustment for
years (decades), but I've had trouble doing that with very thin
spokes. The amount of wind-up varies from spoke to spoke, and even
varies on the same spoke as it is tensioned. This variability makes
it hard to guess correctly how much to back off each nipple.

I've built thin spoke wheels using both the over-shoot-and-back-off
and the hold-spoke-while-adjusting method. The second method is more
reliable, I never get the charcteristic "ping, ping" of untwisting
spokes after using this method. Not so with over-shoot-and-back-off.
--
terry morse - Undiscovered Country Tours - http://www.udctours.com/

Terry Morse writes:

Over the years that I have been building wheels I have heard no
untwisting sounds because I use an over-shoot-and-back-off method
to adjust spokes. Readers of "the Bicycle Wheel" know how to do
that as well, it being mentioned in the book under "Spoke Twist".

I've used the over-shoot-and-back-off method of spoke adjustment for
years (decades), but I've had trouble doing that with very thin
spokes. The amount of wind-up varies from spoke to spoke, and even
varies on the same spoke as it is tensioned. This variability makes
it hard to guess correctly how much to back off each nipple.

I've built thin spoke wheels using both the over-shoot-and-back-off
and the hold-spoke-while-adjusting method. The second method is more
reliable, I never get the characteristic "ping, ping" of untwisting
spokes after using this method. Not so with over-shoot-and-back-off.

There's a fine sense way of assessing windup by feeling the torque
when tightening and loosening a tight spoke. (Only the final
tightening counts.) A tight spoke will begin to twist and then break
loose when it has built up enough torque to make the thread move.
This can be felt and it is different for tightening and loosening
because one is uphill, so to speak, and the other is down the thread
ramp.

This break loose point is difficult to feel if the spoke nipple to rim
interface is not well lubricated. I suspect most people do not pay
attention to that aspect or we wouldn't have spoke wrenches that are
in essence slotted four sided socket wrenches. With my hardened
steel, slotted spoke wrenches, I can twist off any spoke I have met
yet do not round off spoke nipples. That dry cork sound I often hear
when I see wheels being built in bicycle shops is a sure sign that the
brass spoke nipple is galling.

Jobst Brandt

On 21 Dec 2006 11:21:03 GMT, wrote:

[snip]

The
reason for using that many spokes is that a single spoke failure with
fewer, generally means end of ride because the wheel goes too far out
of alignment in tight fitting (modern) frames to continue. We are not
making progress.

Jobst Brandt

Dear Jobst,

For someone who claims that spokes should last forever on wheels built
according to your theory, you seem awfully worried about them
breaking.

Cheers,

Carl Fogel

Terry Morse wrote:

I've used the over-shoot-and-back-off method of spoke adjustment for
years (decades), but I've had trouble doing that with very thin
spokes. The amount of wind-up varies from spoke to spoke, and even
varies on the same spoke as it is tensioned. This variability makes
it hard to guess correctly how much to back off each nipple.

I've built thin spoke wheels using both the over-shoot-and-back-off
and the hold-spoke-while-adjusting method. The second method is more
reliable, I never get the charcteristic "ping, ping" of untwisting
spokes after using this method. Not so with over-shoot-and-back-off.

Terry,

Besides the "hold-spoke-while-adjusting method" you mention, the
variability can be eliminated by marking the spokes, as described he

http://groups.google.com/group/rec.b...4b972918e1096f

Even after building several wheels and developing a "feel" for windup,
I still find it helpful to do this. The only cost is the ~90 seconds it
takes to apply the marks. I've never tried the
"hold-spoke-while-adjusting method", but I suspect it requires more
work than simply marking them.

Best,
Stephen Greenwood

In article
,
Tim McNamara wrote:

In article ,
jim beam wrote:

Tim McNamara wrote:
In article , "PWNMAN"
wrote:

wrote in message
... I believe the
misunderstanding about stresses that case spoke failures arises
because spoke stress is invisible and not easily measured.

Your integrity is invisible and not easily measured also!

Integrity is measured over time. I find it easy to draw
conclusions about the integrity of the participants in this forum
after 13 years or so of participation.

so repetition of an error for a prolonged period makes it not an
error? that's interesting.

No. If that were true, then you'd have integrity.

Left himself wide open for that one. Some people do not
think ahead. It is not only that he does not hearken to
what is said to him, he does not even parse what is
said to him.

--
Michael Press

Stephen Greenwood writes:

I've used the over-shoot-and-back-off method of spoke adjustment
for years (decades), but I've had trouble doing that with very thin
spokes. The amount of wind-up varies from spoke to spoke, and even
varies on the same spoke as it is tensioned. This variability
makes it hard to guess correctly how much to back off each nipple.

I've built thin spoke wheels using both the over-shoot-and-back-off
and the hold-spoke-while-adjusting method. The second method is
more reliable, I never get the characteristic "ping, ping" of
untwisting spokes after using this method. Not so with
over-shoot-and-back-off.

Besides the "hold-spoke-while-adjusting method" you mention, the
variability can be eliminated by marking the spokes, as described
he

http://groups.google.com/group/rec.b...4b972918e1096f

Even after building several wheels and developing a "feel" for
windup, I still find it helpful to do this. The only cost is the
~90 seconds it takes to apply the marks. I've never tried the
"hold-spoke-while-adjusting method", but I suspect it requires more
work than simply marking them.

I also used the marking method and that is how I discovered how poorly
holding spokes with pliers works. As I said, I do fine with backing
off. The test of the method is to coast standing on one pedal while
leaning far to either side. That puts a smooth side load on the wheel
that nearly slacken the spokes.

Jobst Brandt

jim beam wrote:

wrote:

Spoke windup was such a severe problem on early machines
that it limited the ability to reach high tension, something that was
brought to a head with fewer spokes that requires higher tension. It
was the tension limit, caused by spoke windup, that gave machine built
wheels a bad name, and it has, to a degree, stuck.

btw, can you please explain
exactly how the torsional elasticity of a spoke changes with tension?

I think it's clear that spoke windup increases with tension due to
static friction between spoke and nipple, and not to a change in the
properties of the spoke itself. Is the latter what you are suggesting?


Chalo

Stephen Greenwood wrote:

Besides the "hold-spoke-while-adjusting method" you mention, the
variability can be eliminated by marking the spokes, as described he

http://groups.google.com/group/rec.b...4b972918e1096f

Even after building several wheels and developing a "feel" for windup,
I still find it helpful to do this. The only cost is the ~90 seconds it
takes to apply the marks. I've never tried the
"hold-spoke-while-adjusting method", but I suspect it requires more
work than simply marking them.

Thanks, I haven't tried the "mark the spokes" method in quite a
while. Maybe I'll try that on my mext wheel.

For holding the spokes, I have purchased the Twist Resist tool:

http://www.sheldonbrown.com/harris/tools/wheel.html

It's fairly easy to use and does the job.

Chalo wrote:
jim beam wrote:
wrote:
Spoke windup was such a severe problem on early machines
that it limited the ability to reach high tension, something that was
brought to a head with fewer spokes that requires higher tension. It
was the tension limit, caused by spoke windup, that gave machine built
wheels a bad name, and it has, to a degree, stuck.
btw, can you please explain
exactly how the torsional elasticity of a spoke changes with tension?

I think it's clear that spoke windup increases with tension due to
static friction between spoke and nipple, and not to a change in the
properties of the spoke itself. Is the latter what you are suggesting?


Chalo

you got it right, the spoke properties don't change, just the friction.