Need Jobst (and anyone else's) help: Twisted-spoke damping factor

On 5 Dec 2004 01:29:36 -0800, [email hidden] (papercut)

Quoted message said:

From a recent post elsewhere:

Quoted message said:

citing gerd schraner from his book "the art of wheelbuilding" --

Quoted message said:

the twisting of spokes, instead of classic crossing work is a waste

of time for >road use. tests have shown that it results in a very
unstable wheel. the >lateral stability is about the same as a
normally spoked wheel, but radially the >wheel reacts so sluggishly
that encounters with momentary radial overloads the >highly praised
damping effect is delayed. ... twisted spoking patterns are an

Quoted message said:

additional mechanical disadvantage resulting from the extreme angle

of the spoke >directly at the nipple. (schraner, p. 60)

So, there is a claim that wheels with twisted spokes have a
significantly different "damping factor" than normally laced wheels.
The above quote given as evidence.

It is also claimed that this "damping factor" inherent in
twisted-spoke wheels are good for trials riding. This conclusion
deduced somehow.

Sounds like a lot of pseudoscience to me. What's the scoop on this?

Dear PC,

I can think of only two ways to twist spokes.

One way is to barber-pole the individual spoke while
tightening the nipple, something more easily seen (and done)
on bladed spokes. This is a bad thing because the spoke will
untwist and unscrew itself slightly from the nipple, which
means that the rim will go out of true.

Here's the other way to twist spokes, which is probably what
they're talking about:

http://www.ne.jp/asahi/julesandjames/home/disk_and_quick_release/stratos.jpg

This chain-link twisted-spoke pattern might provide some
spring action, with the spokes making 30-degree bends
against each other, but any spring-like action in tensioned
spokes is likely to be dwarfed by the springy nature of the
inflated rubber tire, the flexing of the fork, and the
movement of the grip end of the handlebar when the rider
leans on things.)

(If they meant damping, just replace "spring action" with
"damping action." The same objection remains, whether for
touring or trials, that the rubber tires spring and damp
much more than steel spokes.)

The chain-link pattern looks like just another reminder that
almost any spoke pattern can be pedalled down the road.

Carl Fogel

Quoted message said:

On 5 Dec 2004 01:29:36 -0800, [email hidden] (papercut)

Quoted message said:

From a recent post elsewhere:

Quoted message said:

Quoted message said:

citing gerd schraner from his book "the art of wheelbuilding" --

Quoted message said:

the twisting of spokes, instead of classic crossing work is a waste

of time for >road use. tests have shown that it results in a very
unstable wheel. the >lateral stability is about the same as a
normally spoked wheel, but radially the >wheel reacts so sluggishly
that encounters with momentary radial overloads the >highly praised
damping effect is delayed. ... twisted spoking patterns are an

Quoted message said:

additional mechanical disadvantage resulting from the extreme angle

of the spoke >directly at the nipple. (schraner, p. 60)

So, there is a claim that wheels with twisted spokes have a
significantly different "damping factor" than normally laced wheels.
The above quote given as evidence.

It is also claimed that this "damping factor" inherent in
twisted-spoke wheels are good for trials riding. This conclusion
deduced somehow.

Sounds like a lot of pseudoscience to me. What's the scoop on this?

Dear PC,

I can think of only two ways to twist spokes.

One way is to barber-pole the individual spoke while
tightening the nipple, something more easily seen (and done)
on bladed spokes. This is a bad thing because the spoke will
untwist and unscrew itself slightly from the nipple, which
means that the rim will go out of true.

Here's the other way to twist spokes, which is probably what
they're talking about:

http://www.ne.jp/asahi/julesandjames/home/disk_and_quick_release/stratos.jpg

This chain-link twisted-spoke pattern might provide some
spring action, with the spokes making 30-degree bends
against each other, but any spring-like action in tensioned
spokes is likely to be dwarfed by the springy nature of the
inflated rubber tire, the flexing of the fork, and the
movement of the grip end of the handlebar when the rider
leans on things.)

(If they meant damping, just replace "spring action" with
"damping action." The same objection remains, whether for
touring or trials, that the rubber tires spring and damp
much more than steel spokes.)

in this case, you do get a pronounced spring action. the spokes no
longer axially load. imagine pulling on a piece of wire - not much
spring. now coil that wire, then pull. substantially different results.

Quoted message said:

The chain-link pattern looks like just another reminder that
almost any spoke pattern can be pedalled down the road.

Carl Fogel

jim beam said:

Quoted message said:

On 5 Dec 2004 01:29:36 -0800, [email hidden] (papercut)

Quoted message said:

From a recent post elsewhere:

Quoted message said:

>citing gerd schraner from his book "the art of wheelbuilding" --

>the twisting of spokes, instead of classic crossing work is a waste

of time for >road use. tests have shown that it results in a very
unstable wheel. the >lateral stability is about the same as a
normally spoked wheel, but radially the >wheel reacts so sluggishly
that encounters with momentary radial overloads the >highly praised
damping effect is delayed. ... twisted spoking patterns are an

>additional mechanical disadvantage resulting from the extreme angle

of the spoke >directly at the nipple. (schraner, p. 60)

So, there is a claim that wheels with twisted spokes have a
significantly different "damping factor" than normally laced wheels.
The above quote given as evidence.

It is also claimed that this "damping factor" inherent in
twisted-spoke wheels are good for trials riding. This conclusion
deduced somehow.

Sounds like a lot of pseudoscience to me. What's the scoop on this?

Dear PC,

I can think of only two ways to twist spokes.

One way is to barber-pole the individual spoke while
tightening the nipple, something more easily seen (and done)
on bladed spokes. This is a bad thing because the spoke will
untwist and unscrew itself slightly from the nipple, which
means that the rim will go out of true.

Here's the other way to twist spokes, which is probably what
they're talking about:

http://www.ne.jp/asahi/julesandjames/home/disk_and_quick_release/stratos.jpg

This chain-link twisted-spoke pattern might provide some
spring action, with the spokes making 30-degree bends
against each other, but any spring-like action in tensioned
spokes is likely to be dwarfed by the springy nature of the
inflated rubber tire, the flexing of the fork, and the
movement of the grip end of the handlebar when the rider
leans on things.)

(If they meant damping, just replace "spring action" with
"damping action." The same objection remains, whether for
touring or trials, that the rubber tires spring and damp
much more than steel spokes.)

in this case, you do get a pronounced spring action. the spokes no
longer axially load. imagine pulling on a piece of wire - not much
spring. now coil that wire, then pull. substantially different results.

Quoted message said:

The chain-link pattern looks like just another reminder that
almost any spoke pattern can be pedalled down the road.

Carl Fogel

Dear Jim,

You may be right, but I'm having trouble seeing how things
move more with pairs of spokes twisted around each other.

Assuming that the twisted spokes are tensioned, where's the
spring? That is, doesn't a curved spoke actually have to
elongate more than a straight spoke to produce the same
result in terms of the distance from the nipple to the hub?

And unless the rim deflects substantially, what would
move--the axle in relation to the rest of the wheel? Is the
rim supposed to flatten out significantly more? Or what?

Puzzled,

Carl Fogel

Quoted message said:

jim beam said:

Quoted message said:

On 5 Dec 2004 01:29:36 -0800, [email hidden] (papercut)
wrote:

>From a recent post elsewhere:

>>citing gerd schraner from his book "the art of wheelbuilding" --
>
>>the twisting of spokes, instead of classic crossing work is a waste
>
>of time for >road use. tests have shown that it results in a very
>unstable wheel. the >lateral stability is about the same as a
>normally spoked wheel, but radially the >wheel reacts so sluggishly
>that encounters with momentary radial overloads the >highly praised
>damping effect is delayed. ... twisted spoking patterns are an
>
>
>>additional mechanical disadvantage resulting from the extreme angle
>
>of the spoke >directly at the nipple. (schraner, p. 60)
>
>So, there is a claim that wheels with twisted spokes have a
>significantly different "damping factor" than normally laced wheels.
>The above quote given as evidence.
>
>It is also claimed that this "damping factor" inherent in
>twisted-spoke wheels are good for trials riding. This conclusion
>deduced somehow.
>
>
>Sounds like a lot of pseudoscience to me. What's the scoop on this?

Dear PC,

I can think of only two ways to twist spokes.

One way is to barber-pole the individual spoke while
tightening the nipple, something more easily seen (and done)
on bladed spokes. This is a bad thing because the spoke will
untwist and unscrew itself slightly from the nipple, which
means that the rim will go out of true.

Here's the other way to twist spokes, which is probably what
they're talking about:

http://www.ne.jp/asahi/julesandjames/home/disk_and_quick_release/stratos.jpg

This chain-link twisted-spoke pattern might provide some
spring action, with the spokes making 30-degree bends
against each other, but any spring-like action in tensioned
spokes is likely to be dwarfed by the springy nature of the
inflated rubber tire, the flexing of the fork, and the
movement of the grip end of the handlebar when the rider
leans on things.)

(If they meant damping, just replace "spring action" with
"damping action." The same objection remains, whether for
touring or trials, that the rubber tires spring and damp
much more than steel spokes.)

in this case, you do get a pronounced spring action. the spokes no
longer axially load. imagine pulling on a piece of wire - not much
spring. now coil that wire, then pull. substantially different results.

Quoted message said:

The chain-link pattern looks like just another reminder that
almost any spoke pattern can be pedalled down the road.

Carl Fogel

Dear Jim,

You may be right, but I'm having trouble seeing how things
move more with pairs of spokes twisted around each other.

Assuming that the twisted spokes are tensioned, where's the
spring? That is, doesn't a curved spoke actually have to
elongate more than a straight spoke to produce the same
result in terms of the distance from the nipple to the hub?

And unless the rim deflects substantially, what would
move--the axle in relation to the rest of the wheel? Is the
rim supposed to flatten out significantly more? Or what?

Puzzled,

Carl Fogel

the coiled spring is an illustrative example. _any_ deviation from
straight will increase flexibility experienced. yes, it's supported by
the other spoke, and the effect is mitigated by the [in]flexibility of
the rim, but the principle still applies.

jim beam said:

the coiled spring is an illustrative example. _any_ deviation from
straight will increase flexibility experienced. yes, it's supported
by the other spoke, and the effect is mitigated by the [in]flexibility
of the rim, but the principle still applies.

I don't see how the example of a coil spring is germane. Coil springs
work by converting linear motion to torsion. How does this apply to
snowflake wheels?

Jim Smith said:

jim beam said:

the coiled spring is an illustrative example. _any_ deviation from
straight will increase flexibility experienced. yes, it's supported
by the other spoke, and the effect is mitigated by the [in]flexibility
of the rim, but the principle still applies.

I don't see how the example of a coil spring is germane. Coil springs
work by converting linear motion to torsion. How does this apply to
snowflake wheels?

Dear Jim,

Well, the spokes do twist around each other, with each spoke
making a sort of half-hearted single coil.

But unlike a free coil spring, they're linked like a
chain-link fence. And unlike the chain-link fence strands,
each spoke is presumably under considerable tension.

It might make things clearer if someone could give some
numbers for comparison, such as how much tension is used and
how much the rim (and how long a span of it) would deflect
for both straight cross-3 spokes and for snowflake pattern
twisted spokes.

I still suspect that the rubber inflated tires, the front
fork, the handlebars, and the seat plus seat post would both
give and damp far more than stainless steel spokes,
regardless of spoke pattern.

Carl Fogel

<[email hidden]> wrote: (clip) But unlike a free coil spring, they're
linked like a chain-link fence. And unlike the chain-link fence strands,
each spoke is presumably under considerable tension.(clip)
^^^^^^^^^^^^^^
I think the comparison to a chain-link fence is valid. When the fence is
erected, tension is applied to take out sag. As the fence is stretched into
position, the curvature at each crossing changes. It takes less force to
move the fence weave than it would to stretch the equivalent straight wires.
Similarly, I believe it would take less force to stretch the woven spokes
than straight spokes--they can extend by sharpening the curvature at the
intersections, which takes less force than extending in direct tension.

This seems clear to me; I hope my effort to explain it is not too murky.

Leo Lichtman said:

<[email hidden]> wrote: (clip) But unlike a free coil spring,
they're linked like a chain-link fence. And unlike the chain-link fence
strands, each spoke is presumably under considerable tension.(clip)
^^^^^^^^^^^^^^ I think the comparison to a chain-link fence is valid.
When the fence is erected, tension is applied to take out sag. As the
fence is stretched into position, the curvature at each crossing changes.
It takes less force to move the fence weave than it would to stretch the
equivalent straight wires. Similarly, I believe it would take less force
to stretch the woven spokes than straight spokes--they can extend by
sharpening the curvature at the intersections, which takes less force
than extending in direct tension.

This seems clear to me; I hope my effort to explain it is not too murky.

They can't "sharpen their curvature" if it's already been sharpened to the
maximum, which might be the case on a properly tensioned wheel; and if not,
would lead to spokes failing more quickly at these crossings, I believe.

--
Benjamin Lewis

Seeing is deceiving. It's eating that's believing.
-- James Thurber

Leo Lichtman said:

... I believe it would take less force to stretch the woven spokes
than straight spokes...

Unless you build your wheels such that the hubs hang from the upper
spokes, I don't think anything should be stretching much.

Quoted message said:

Jim Smith said:

jim beam said:

the coiled spring is an illustrative example. _any_ deviation from
straight will increase flexibility experienced. yes, it's supported
by the other spoke, and the effect is mitigated by the [in]flexibility
of the rim, but the principle still applies.

I don't see how the example of a coil spring is germane. Coil springs
work by converting linear motion to torsion. How does this apply to
snowflake wheels?

Dear Jim,

Well, the spokes do twist around each other, with each spoke
making a sort of half-hearted single coil.

But unlike a free coil spring, they're linked like a
chain-link fence. And unlike the chain-link fence strands,
each spoke is presumably under considerable tension.

It might make things clearer if someone could give some
numbers for comparison, such as how much tension is used and
how much the rim (and how long a span of it) would deflect
for both straight cross-3 spokes and for snowflake pattern
twisted spokes.

I still suspect that the rubber inflated tires, the front
fork, the handlebars, and the seat plus seat post would both
give and damp far more than stainless steel spokes,
regardless of spoke pattern.

Carl Fogel

it's not a straight line between the two anchor points. anything that
does not take this straight line in not in pure axial load. non-axial =
greater deflection. the coil spring is a a polar extreme. _any_ shape,
whether coil, random, zigzag, clothes hanger, _any_ shape that is not
the pure axial load will bend at any point not directly on the load
axis. bracing adds complexity to the math, but the same principles
still apply.

"jim beam" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Quoted message said:

Jim Smith said:

jim beam <[email hidden]> writes:

>the coiled spring is an illustrative example. _any_ deviation from
>straight will increase flexibility experienced. yes, it's supported
>by the other spoke, and the effect is mitigated by the [in]flexibility
>of the rim, but the principle still applies.

I don't see how the example of a coil spring is germane. Coil springs
work by converting linear motion to torsion. How does this apply to
snowflake wheels?

Dear Jim,

Well, the spokes do twist around each other, with each spoke
making a sort of half-hearted single coil.

But unlike a free coil spring, they're linked like a
chain-link fence. And unlike the chain-link fence strands,
each spoke is presumably under considerable tension.

It might make things clearer if someone could give some
numbers for comparison, such as how much tension is used and
how much the rim (and how long a span of it) would deflect
for both straight cross-3 spokes and for snowflake pattern
twisted spokes.

I still suspect that the rubber inflated tires, the front
fork, the handlebars, and the seat plus seat post would both
give and damp far more than stainless steel spokes,
regardless of spoke pattern.

Carl Fogel

it's not a straight line between the two anchor points. anything that
does not take this straight line in not in pure axial load. non-axial =
greater deflection. the coil spring is a a polar extreme. _any_ shape,
whether coil, random, zigzag, clothes hanger, _any_ shape that is not
the pure axial load will bend at any point not directly on the load
axis. bracing adds complexity to the math, but the same principles
still apply.

Twisting two spokes together just couples them in the sense of coupling two
springs together. The effect of this is to make the spoke (effectively)
more compliant, exactly like reducing the diameter. It will not affect
damping, since that would require the introduction of friction.

I see no advantage to this not obtained more easily with butted spokes, and
there are disadvantages: the effect of spoke breakage is doubled (actually
worse, since they are adjacent), and the angle at the nipple is bad.

"Benjamin Lewis" wrote: They can't "sharpen their curvature" if it's
already been sharpened to the maximum, (clip)
^^^^^^^^^^^
Benjamin, I just went back and looked at the illustration in Car Fogel's
link. The spokes in that wheel have considerable room for additional
tightening, comparable to what I was referring to in a chain link fence. In
order to eliminate all that "give," they would have to be bent sharply at
the intersections. I don't think that could be achieved merely by
tightening the nipples.

Peter Cole said:

Twisting two spokes together just couples them in the sense of
coupling two springs together. The effect of this is to make the
spoke (effectively) more compliant, exactly like reducing the
diameter. It will not affect damping, since that would require the
introduction of friction.

This can be simplified and at the same time take out any inelegant
bends that might change elasticity, by pulling the to-be-twisted spoke
pairs together by tying a collar of some type around them (and giving
them a kink) so they lie straight in their free runs. It boils down
to the previous discussion where all this does is make two spokes
"fail" when one of them fails.

Quoted message said:

I see no advantage to this not obtained more easily with butted
spokes, and there are disadvantages: the effect of spoke breakage is
doubled (actually worse, since they are adjacent), and the angle at
the nipple is bad.

That's my take on this as well. But what did Schraner mean by all
this and why did he bring it up in his book without any supporting
explanation or evidence?

Jobst Brandt
[email hidden]

Leo Lichtman said:

Quoted message said:

They can't "sharpen their curvature" if it's already been sharpened
to the maximum, (clip) ^^^^^^^^^^^^

Quoted message said:

Benjamin, I just went back and looked at the illustration in Car
Fogel's link. The spokes in that wheel have considerable room for
additional tightening, comparable to what I was referring to in a
chain link fence. In order to eliminate all that "give," they would
have to be bent sharply at the intersections. I don't think that
could be achieved merely by tightening the nipples.

If there are any flexing bends, then you can be sure spokes will fail
in fatigue in a short time. This has no advantage.

Jobst Brandt
[email hidden]

On 5 Dec 2004 01:29:36 -0800, [email hidden] (papercut)

Quoted message said:

From a recent post elsewhere:

Quoted message said:

citing gerd schraner from his book "the art of wheelbuilding" --

Quoted message said:

the twisting of spokes, instead of classic crossing work is a waste

of time for >road use. tests have shown that it results in a very
unstable wheel. the >lateral stability is about the same as a
normally spoked wheel, but radially the >wheel reacts so sluggishly
that encounters with momentary radial overloads the >highly praised
damping effect is delayed. ... twisted spoking patterns are an

Quoted message said:

additional mechanical disadvantage resulting from the extreme angle

of the spoke >directly at the nipple. (schraner, p. 60)

So, there is a claim that wheels with twisted spokes have a
significantly different "damping factor" than normally laced wheels.
The above quote given as evidence.

It is also claimed that this "damping factor" inherent in
twisted-spoke wheels are good for trials riding. This conclusion
deduced somehow.

Sounds like a lot of pseudoscience to me. What's the scoop on this?

Here's a better picture of the snowflake, chain-link,
twisted-spoke pattern, showing the whole wheel:

http://www.dtonline.org/structures/get.html?_Action=GetImage&_Key=MainImage&_Id=14&_Wizard=0&_DontCache=1062613691&_Where=AllValidated
or http://tinyurl.com/5jhy4

Carl Fogel

[email hidden said:

"]On 5 Dec 2004 01:29:36 -0800, [email hidden] (papercut)

Quoted message said:

From a recent post elsewhere:

Quoted message said:

citing gerd schraner from his book "the art of wheelbuilding" --

Quoted message said:

the twisting of spokes, instead of classic crossing work is a waste

of time for >road use. tests have shown that it results in a very
unstable wheel. the >lateral stability is about the same as a
normally spoked wheel, but radially the >wheel reacts so sluggishly
that encounters with momentary radial overloads the >highly praised
damping effect is delayed. ... twisted spoking patterns are an

Quoted message said:

additional mechanical disadvantage resulting from the extreme angle

of the spoke >directly at the nipple. (schraner, p. 60)

So, there is a claim that wheels with twisted spokes have a
significantly different "damping factor" than normally laced wheels.
The above quote given as evidence.

It is also claimed that this "damping factor" inherent in
twisted-spoke wheels are good for trials riding. This conclusion
deduced somehow.

Sounds like a lot of pseudoscience to me. What's the scoop on this?

Here's a better picture of the snowflake, chain-link,
twisted-spoke pattern, showing the whole wheel:

dtonline.orgget.htmlOpen ↗
or tinyurl.com5jhy4Open ↗

Carl Fogel

Viewed the picture, looks ugly. Like a "pre-ruined" wheel. Bet it costs a lot of money to get it done too. Would go well with some of the new high end Pinarellos.

"waxbytes" wrote: Viewed the picture, looks ugly. Like a "pre-ruined" wheel.
Bet it costs a lot of money to get it done too.
^^^^^^^^^^^^^
On top of everything else, how would you determine the right spoke length to
use, short of trial and error?

"Leo Lichtman" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

"waxbytes" wrote: Viewed the picture, looks ugly. Like a

"pre-ruined" wheel.

Quoted message said:

Bet it costs a lot of money to get it done too.
^^^^^^^^^^^^^
On top of everything else, how would you determine the right

spoke length to

Quoted message said:

use, short of trial and error?

Buy long, and just keep twisting until you get to the right
length.

With all the interest generated by this thread, I fear that the
next K$yrium wheels will have aluminum twisted spokes, or maybe
the Spox will come out with a fully laced doily pattern. As Mike
puts it in the RaceLite thread, this would "offer yet another way
to differentiate or classify a bike" -- which I suppose is reason
enough to build something like this. -- Jay Beattie.

On 5 Dec 2004 01:29:36 -0800, [email hidden] (papercut)

Quoted message said:

From a recent post elsewhere:

Quoted message said:

citing gerd schraner from his book "the art of wheelbuilding" --

Quoted message said:

the twisting of spokes, instead of classic crossing work is a waste

of time for >road use. tests have shown that it results in a very
unstable wheel. the >lateral stability is about the same as a
normally spoked wheel, but radially the >wheel reacts so sluggishly
that encounters with momentary radial overloads the >highly praised
damping effect is delayed. ... twisted spoking patterns are an

Quoted message said:

additional mechanical disadvantage resulting from the extreme angle

of the spoke >directly at the nipple. (schraner, p. 60)

So, there is a claim that wheels with twisted spokes have a
significantly different "damping factor" than normally laced wheels.
The above quote given as evidence.

It is also claimed that this "damping factor" inherent in
twisted-spoke wheels are good for trials riding. This conclusion
deduced somehow.

Sounds like a lot of pseudoscience to me. What's the scoop on this?

And here's an even better pair of pictures of the snowflake,
chain-link, twisted-spoke wheel:

http://www.ozbizz.com/melton/kensbikes/snowflake.htm

Note that these Australian wonders have a double-twist,
producing God knows what kind of effect.

Technically, this has moved beyond chain-link to
chicken-wire.

Now I'm hoping to find a wheel with four spokes twisted.

Carl Fogel