The Basics of Wheel Alignment and Wheelbuilding

On Fri, 6 Aug 2004 07:35:16 +0100, "Trevor Jeffrey"
wrote:


wrote in message ...
On Fri, 6 Aug 2004 00:42:55 +1000, Weisse Luft
wrote:
.

But you're saying that the variation of the spoke load is
less. Is this a matter of both thick and thin spokes being
tensioned to X pounds and the thick one going to 0 pounds
of tension, a variation of X, while the more elastic thinner
spoke doesn't drop as far--say to 10 lbs tension--and
therefore has a smaller load range of X -10 instead of the
full range of X.

Presumably spokes last longer with this smaller load
variation. I'm hoping that I've managed to figure out what
you (and others) already understood, since it seems clearer
than waving my hands and declaring that losing all tension
is a bad thing.

Steels tested for this, have not shown it to be evident.
Reduction of magnitude of load variation may increase life of sample, but
the increase of tension before applying load variation does not show
benefits for component life.

TJ


Dear Trevor,

Actually, I wrote that, not Weisse Luft.

You may have misunderstood something here.

As far as I know, both the butted spokes with the thinner
midsection and the straight spokes would be tensioned to
the same force of X pounds of tension.

It's the increased elasticity of the thinner double-butted
spoke that reduces the variation of tension.

When the thicker and therefore less elastic straight spokes
contract enough to go from X pounds to 0 pounds of tension,
they have experienced the full range of possible tension
variation.

In the same situation, the thinner and therefore more
elastic double-butted spokes start at the same X pounds of
tension, but do not relax to 0 pounds of tension. Their
range of variation is therefore smaller.

Again, both kinds of spokes began at the same tension in the
wheel. The difference is that the thick spokes will lose all
tension well before the thin spokes do.

Carl Fogel

Trevor Jeffrey wrote:
Mark McMaster wrote in message ...

Trevor Jeffrey wrote:

Mark McMaster wrote in message ...

As far as the role of the rim, it's main role is supply a
continuously round surface to mount the tire, /


INCORRECT The rim provides the rolling surface and the tyre reduces

rolling

resistace and provides grip to assist traction. I consider a tyre should
also reduce jarring.

How can you say that the rim provides the rolling surface,
if the wheel doesn't roll on the surface of the rim? /


I assure you it can. I have ridden a bare rim after tearing a tyre cased by
wheel collapse (constructed as instructed in JB's book) during sprinting.
It was the poor stability of this wheel made me want to investigate further
on constructional techniques.

I'm confused - how could your wheel collapse so badly that
it tore the tire casing, and yet still be in good enough
shape that you could ride on it? I've never seen a
collapsed wheel tear a tire casing, although I suppose it
could happen; I've never seen a collapsed wheel that would
still roll.



Also,
you are entirely incorrect about the tire reducing rolling
resistance - it increases the rolling resistance, not
decreases it. /


Robert Thompson and John Dunlop etc would disagree.

Rolling resistance was not the issue that Thompson and
Dunlop were trying to address.

The thing that is interesting here is that you can not
possibly have researched whether pneumatic tires reduce
rolling resistance over solid wheels. If you had, you would
have found numerous resources showing that the flexing of
the pneumatic tire casing (and tread) increases the rolling
resistance compared to a solid wheel. Here are a few:

http://www.lafn.org/~dave/trans/energy/rail_energy.html
http://www.channel4.com/science/micr...r/Science.html

Why do you do this? Why do you make completely unverified
assertions based on pre-conceptions and wild guesses, and
then defend them as if they were absolute truths? You have
offered absolutely no objective evidence to back up anything
you claim.


If tires decreased rolling resistance,
railroad cars would roll on pneumatic tires instead of
directly on their solid wheels./


Oh no they wouldn't. Oh yes they do. But where? I cannot recall.
The railway carriage was in existence long before the invention of the
pneumatic tyre. Wheels are large and the track is smooth and resilient.
Notice the use of the word track, a carriage wheel has to track the line
accurately at high speed under braking and acceleration in straight lines
and around curves. This is acheived through special shaping of the wheel's
tyre and the track. The track is cambered. Railway locomotives are heavy,
the complications to use pneumatic tyres resilient enough for this
application are great. It would be impossible to convert to a pnuematic
tyred rail system.

Impossible? No. Impractical? In some cases. Pneumatic
tires for railroad wheels actually are in service in some
locations:

http://www.skytraincorp.com/wheels-maglev.htm
http://encyclopedia.thefreedictionar...%20underground

(Note, the second web site has a reference to the added
rolling resistance caused by rubber tires as a disadvantage
to their use on railroad wheels.)


If you had looked at the analyses of spoke tension changes
when a wheel is loaded more carefully, you would see that
the summation of the spoke tensions _decrease_ when a wheel
is loaded. In other words, there are large spoke tension
decreases directly at the bottom of the wheel, and only very
small spoke tension increases elsewhere around the rim. The
total sum of the spoke tension increases is far less than
the sum of the spoke tension decreases. Although there may
be some increases in rim compression around parts of the
wheel due to the small spoke tension increases, they are
very small.


This is complex, innaccurate and irrelevant. It is absurd that you wish

to

persuade that the spokes change tension to move the rim, the force on a
loaded wheel is generally in directions so as to bring together rim and

hub

in the lower portion of the wheel. To suggest that the spokes act to

move

the rim is incongruous of an inanimate object. The point is stated

above,

the spokes transfer the load from the rim to the hub. I know not of

which

analysis you seem to think I have looked at. If it suggests that which

you

have indicated, it is worthless.

It appears that you are suffering from cognitive dissonance.
During discussions on wheel mechanics, you become agitated /


I really don't. Don't make false accusations.

Apparently you do. When I simply commented on the data (not
the conclusions) of tests regarding spoke tension changes in
loaded bicycle wheels, you claim they are "complex,
inaccurate and irrelevant." The raw data is not complex, it
is simply direct measurements of tension changes. It is not
inaccurate, as they have been independently verified by
several unrelated organizations. And if measurements of the
distributions of forces in a wheel are irrelevant to how a
wheel supports a load, then you must think it is done by
magic instead.


whenever the actual measured tension changes in a loaded
wheel is pointed, because they don't jibe with your
particular views.


It is still uneccasary and irrelevant, you only bring it up to cause
diversion.

No, the ignoring direct data of wheel forces in determining
how wheel works is a diversion from finding the truth.
Again I ask - what objective evidence do you base your
beliefs on? If you have no evidence to support your
statements (and all other available evidence disputes it)
you must be wrong.


May I remind you, any reference I have made to wheel loading, assumes
spokes which are not pre-tensioned. My method of wheelbuilding specifically
aims to reduce pre-loading of the rim to the minimum required to prevent
loss of lateral stability during service. As long as spokes do not become
loose, lateral stability is maintained. I was not prepared for and did not
want a discussion on load theory of the wheel as it depends upon components
used and actual constructional technique. Please note that the heading of
the thread is "The Basics of Wheel Alignment and Wheelbuilding"

Ah, but the available evidence shows that the bottom spokes
do lose tension when the wheel is loaded. How do guarantee
that the spokes don't become completely slack, as you have
said is required to maintain lateral stability, if the
spokes are pre-tensioned?


The changes in spoke tension in a loaded wheel have been
analyzed and measured several times. They always lead to
the same conclusions about how loads are distributed through
out the wheel components. In case you need reminding (and
it appears you do) of the spoke tension changes, here are a
few links to some finite element analyses and direct
measurements:

http://www.achrn.demon.co.uk/astounding/ian/wheel/
http://www.rose-hulman.edu/~fine/FE2...ects/Hartz.pdf
http://www.duke.edu/~hpgavin/papers/...heel-Paper.pdf
http://groups.google.com/groups?q=sp...&hl=en&lr=&ie=

UTF-8&c2coff=1&selm=34AE9E7E.3593%40usit.net&rnum=3

There are also other published tests and analyses not on the
web.



This
is because this loading mode can apply a high load
tangential to the rim./


You do not understand arches do you? Please ignore previous statement

and

ammend to " I see you've heard of arches." All serviceable loads

directed

through a wheel through the plane of that wheel will be restrained by

the

rim. This is because the rim acts as an arch and changes the direction

of

load through 90deg to travel along that arch.

No, absolutely not. Neither an arch, nor any other static
structure, can eliminate a force vector component. Newton's
3rd law states that every action has equal and opposite
reaction. If a vertical force is applied to a structure,
there must be an equal and opposite vertical force to
support it. An arch can not make a vertical force
horizontal. There may be an additional horizontal force
generated (which again must have an equal and opposite force
to support it), but an arch can not make any force vector
disappear. This is basic freshman statics. I suggest you
review a pertinent text book.



of the rim to the front and back of the wheel. If
this were so, then the loads would have to then be
transferred (by compression) to the top 180 degree arch of
rim. But if that were the case, in order to support this
load on the top arch of the rim, you would see corresponding
increases in tension in the spokes at the top of the wheel,
supporting the arch. However, all the analyses and
measurements have shown that the small spoke tension
increases that do occur at the top aren't nearly enough to
support the load. Looking at the analysis in the first web
site cited above, out of the 1000 N load applied at the
bottom of the wheel, The vertical components of all the top
spokes combined are only 100 N (10%). Where is the rest of
the load being supported? Look at the bottom of the wheel,
and you can see tension decreases account for about 950 N
(95%) of the load. (Further, you'll see that there are
spoke tension increases below rim, of about 5% of the total
load). The only conclusion that can be reached is that the
rim does not act like a classic arch, and only transfer a
small portion of the external load to the top of the wheel.

So, your theory that a load on the wheel increases
compression on the rim is clearly inconsistent with the
actual data.


Is the data relevant, is it shown that the spokes are adequately tensioned
and not over-tensioned? By this I mean that the spokes will become loose
when the service load is exceeded.

I don't know what you mean by asking if "the spokes are
adequately tensioned and not over-tensioned?". Spoke
components are made from linearly elastic materials (metals)
so as long as the spokes are adequately tensioned and do not
completely slacken, nor exceed their elastic limit, the
results are valid (and since there is little increase in
tension in any spokes when the wheel is loaded, it is
unlikely they will exceed their elastic limit.)


Is it also shown that the spokes take a
direct line and are not looped around each other. Unless these conditions
are satisfied, it is improbable that the data would corespond to my wheel
build. If you disagree, perhaps you may think it raises serious doubt.

If you had actually looked at the data, you would see that
wheels both radially laced, and with crossed (interlaced)
spokes were examined. Again you are not doing your research.




If there is little increase in the tension in
the top spokes, there can be little increase in compression
in the top half of the rim, which means that there is little
rim compression transferred from the bottom half of the
rim. Therefore, the load on a wheel is not transferred

from the ground to the hub primarily by rim compression.

You make an assumption based on pre-conceived ideas and measurements on
others wheels. My statements hold true for a wheel not pre-tensioned.
So how does the load transfer between tyre and spokes if not by compression?
Faries?

No, there are no assumptions. They are simply the logical
conclusions based on the data and known laws of nature.


The magnitudes of the spoke tension changes have been
measured and calculated by many independent parties, who
have all discovered


What they set out to "discover"

The aim to discover how a bicycle wheel actually supports a
load. What are you trying to discover?


the same patterns of load distribution.
You can not simply dismiss the data, just because it
doesn't match your ideas. If your theory can not account
for the load distribution, your theory is wrong. Even if
you do manage to concoct a some convoluted explanation to
make your theory fit, that still doesn't make it correct.


I'll remind you, my aim was to reduce the tensioning of spokes to the
minimum required, and that this was acheivable throughthe pre-forming of the
spoke at its crossing.

How does pre-forming of the spokes at the crossing minimize
the pre-tensioning? The spokes at the bottom of the wheel
loose tension, regardless of the path they take from the hub
to the rim.


Occam's razor says that the simplest theory is the best -
the theory that the external load is carried by the
decreases in tension of a pre-tensioned wheel is simple,
direct, and matches all the known data.


It would not apply should the spokes be loose before loading, so does not
apply to all tensile spoked wheels. To exclude some wheels because they are
not up to some sort of arbitary tension is not a valid argument to support
the theory that the wheel is supported by a decrease in tension.

But if they are not up to adequate tension, then when the
bottom spokes slacken with load, they fail your test of
maintaining lateral stability. Therefore, any wheel which
remains stable must be pre-tensioned, and any wheel that is
pre-tensioned supports loads by decreases in tension.


Your explanation on a pretensioned wheel is influential without resorting to
the sites. I'll give it further thought.

That is a poor approach. Your thoughts should be guided by
the physical evidence, and not by what you assume the
physical evidence should be based on your mental ramblings.



I think this 95% shift may only occur in a grossly pre-tensioned wheel.
My methods do not require gross pre-tensioning so how similar, measured
results will be is questionable.

Wheels are linearly elastic, so the decrease tension of the
bottom spokes equal to 95% of the load will be the same
regardless of the the initial tension in spokes. (This is
required by Hooke's Law.)



The fact still remains that lateral and radial stability along with reduced
spoke failures can be attained by pre-forming the spokes at their crossing.

Please elaborate. The forces inside the wheel caused not
the external load can not be eliminated, only
re-distributed. How does your pre-forming change the force
distribution?

Interestingly, you have laid out all the pieces on how
wheels support a load, you just have to put them together.
A load on a wheel causes a decrease in tension in the bottom
spokes almost equal to the applied load. The bottom spokes
must not completely slacken, or the wheel loses lateral
support. Therefore, the spokes in the bottom wheel must
have some pre-tension, to keep from slackening when a load
is applied. Since the greater the applied load, the more
tension is lost in the bottom spokes, higher loads require
more spoke pre-tension. In other words, the strength of the
wheel is directly related to the amount of static tension in
the spokes. Of course, there are practical limits to how
much static spoke tension a given wheel can stand, but in
general, a tighter wheel is a stronger wheel.

Mark McMaster

Right on all accounts, Mark. The fact that all spoke failures I have
seen, save one SPECIAL case, have been at the ends with NO measurable
change in cross sectional area. The one special case was where a
foreign object was wedged in between the failed spoke and the fork.
This spoke has the classic ductile failure with necking to an eventual
small cup and cone fracture.

This failure analysis is highly indicative of cyclic fatigue, not over
tension. While its possible to over tension a wheel (and I have done
it experimentally), the resulting increase in tension does not
increase the failure rate of the spokes.

Because the wire spoked wheel is a pretensioned structure, the tension
and count of the spokes must match the rim and the load. Here is the
art of wheel building.

I have a friend who had his designer wheels rebuilt with straight gauge
spokes in lieu of DT Revolutions because of a spoke failure. This was
recommended by the LBS, not the wheel's manufacturer. He has not been
able to ride more than 50 miles without loss of tension and a retrue
even though the spokes initially are at the limit of normal tensioning.
Oh yes, these are a paired spoke wheels with a low count. More elastic
spokes ARE the answer.


--
Weisse Luft

wrote in message
...
On Fri, 6 Aug 2004 07:06:12 +0100, "Trevor Jeffrey"
wrote:

[snip]

I have ridden a bare rim after tearing a tyre cased by
wheel collapse (constructed as instructed in JB's book) during sprinting.
It was the poor stability of this wheel made me want to investigate
further
on constructional techniques.

[snip]


Dear Trevor,

Could you explain this a bit more?

That is, what exactly does "wheel collapse" mean to you?
It sounds catastrophic, since it caused a torn tire.

Wheel buckled to lock up in frame pitching me to ground.

Did you somehow repair this wheel and continue riding on it
after removing the tire? Or was there a later experiment?

tyre was torn where rim joint had twisted, tyre not repairable and was
removed.
rim wsa partially straightened in drainage grid and front brake pulled to
one side as it could not be relaxed to a\llow for rim oscillations.

I assume, perhaps incorrectly, that you built a wheel to the
best of your ability to Jobst Brandt's suggestions and feel
that it had "poor stability" because it collapsed, not that
the wheel suffered from "poor stability" after it collapsed,
was repaired, and was ridden with no tire.

The wheel was constructed to the letter of the method suggested, it had
poor lateral stability and it collapsed during sprinting, this is self
evident.
TJ

Mark McMaster wrote in message ...


Rolling resistance was not the issue that Thompson and
Dunlop were trying to address.

So what issues?
Patent spec. 10,990 10 June 1846 Robert William Thomson
"The nature of my said Invention consists in the application of elastic
bearings round the tires of the wheels of carriages, for the purpose of
lessening the power required to draw the carriages, rendering their motion
easier and diminishing the noise they make when in motion."

Impossible? No. Impractical? In some cases. Pneumatic
tires for railroad wheels actually are in service in some
locations:

As I said.

(Note, the second web site has a reference to the added
rolling resistance caused by rubber tires as a disadvantage
to their use on railroad wheels.)

That would be the rolling resistance over a typical railroad wheel running
on a purpose designed track and has minimal relationship to a bicycle wheel
which can run over soft ground.




It appears that you are suffering from cognitive dissonance.
During discussions on wheel mechanics, you become agitated /


I really don't. Don't make false accusations.


It is still uneccasary and irrelevant, you only bring it up to cause
diversion.

No, the ignoring direct data of wheel forces in determining
how wheel works is a diversion from finding the truth.
Again I ask - what objective evidence do you base your
beliefs on? If you have no evidence to support your
statements (and all other available evidence disputes it)
you must be wrong.

To say that force is transfered by the rim to the spokes to the hub was not
something I thought needed explanation because the newsthread appeared to
be about how to build a better wheel. Of which I put forward my
explanation of how I managed it. You on the other hand persist in
constantly going off topic on many different lines in an attempt to
discredit my postings.

Ah, but the available evidence shows that the bottom spokes
do lose tension when the wheel is loaded. How do guarantee
that the spokes don't become completely slack, as you have
said is required to maintain lateral stability, if the
spokes are pre-tensioned?

This is a bit garbled. I hope the following answers the question that you
think you were asking. I have stated that a wheel's spokes do not require
pre-tensioning to function. I have stated a wheel's spokes require a
modicum of tensioning during build, sufficient to prevent loose spokes
under maximum load predicted by cornering and braking. I have also stated
that the fear of a loose spoke is unfounded.

the

rim. This is because the rim acts as an arch and changes the direction

of

load through 90deg to travel along that arch.

No, absolutely not. Neither an arch, nor any other static
structure, can eliminate a force vector component. Newton's
3rd law states that every action has equal and opposite
reaction. If a vertical force is applied to a structure,
there must be an equal and opposite vertical force to
support it. An arch can not make a vertical force
horizontal. There may be an additional horizontal force
generated (which again must have an equal and opposite force
to support it), but an arch can not make any force vector
disappear. This is basic freshman statics. I suggest you
review a pertinent text book.

And the load is transfered by the spokes is what I said, I did not go into
detail because it depends on how much tension is in the spokes on the
predominant manner on exactly the way the load is transferred. Plus it was
not relevant for my method to acertain the precise load values at any one
moment. It being sufficient to know that the rotating wheel produces cyclic
variation in the spokes, so that a spoke and its 'pair' will have relative
changes in tension as they rotate. It is the relative changes in tension
which move the spoke crossing in an out so as to cause the fatigue failure
at the hub.


I don't know what you mean by asking if "the spokes are
adequately tensioned and not over-tensioned?". Spoke
components are made from linearly elastic materials (metals)
so as long as the spokes are adequately tensioned and do not
completely slacken, nor exceed their elastic limit, the
results are valid (and since there is little increase in
tension in any spokes when the wheel is loaded, it is
unlikely they will exceed their elastic limit.)

By over-tensioned, I mean that the tension within the spokes is liable to
cause the rim to buckle due to excessive compression without adequate
lateral support. Buckling is the usual failure of long slim members in
compression, my method not only addresses the problem of fatigue failure at
the spoke heads, it also improves lateral stability and reduces rim
compression so allowing a more predictable wheel.



Is it also shown that the spokes take a
direct line and are not looped around each other. Unless these
conditions
are satisfied, it is improbable that the data would corespond to my wheel
build. If you disagree, perhaps you may think it raises serious doubt.

If you had actually looked at the data, you would see that
wheels both radially laced, and with crossed (interlaced)
spokes were examined. Again you are not doing your research.

I stated I had not examined the wesite. I have done my research.
Check the patent cited at the top of this posting.



If there is little increase in the tension in
the top spokes, there can be little increase in compression
in the top half of the rim, which means that there is little
rim compression transferred from the bottom half of the
rim. Therefore, the load on a wheel is not transferred

from the ground to the hub primarily by rim compression.

You make an assumption based on pre-conceived ideas and measurements on
others wheels. My statements hold true for a wheel not pre-tensioned.
So how does the load transfer between tyre and spokes if not by
compression?
Faries?

No, there are no assumptions. They are simply the logical
conclusions based on the data and known laws of nature.
So how is the load tranferred between tyre and spokes?



The magnitudes of the spoke tension changes have been
measured and calculated by many independent parties, who
have all discovered


What they set out to "discover"

The aim to discover how a bicycle wheel actually supports a
load. What are you trying to discover?

How to make the most reliable wheel, of which I have given my account of my
method and why it is better. Why do you persist in going off topic?


How does pre-forming of the spokes at the crossing minimize
the pre-tensioning? The spokes at the bottom of the wheel
loose tension, regardless of the path they take from the hub
to the rim.

The pre-forming of the spokes reduces the frequency of fatigue failure at
the hub. Without pre-forming the tension of the spokes required to matched
the radial stability is much greater, resulting in excessive rim compression
with the lateral instability that results.
The

It would not apply should the spokes be loose before loading, so does not
apply to all tensile spoked wheels. To exclude some wheels because they
are
not up to some sort of arbitary tension is not a valid argument to
support
the theory that the wheel is supported by a decrease in tension.

But if they are not up to adequate tension, then when the
bottom spokes slacken with load, they fail your test of
maintaining lateral stability. Therefore, any wheel which
remains stable must be pre-tensioned, and any wheel that is
pre-tensioned supports loads by decreases in tension.

A theory on wheel support is incorrect if it excludes those specious wheels,
which although servicable, would not be normally acceptable for service. To
say the rim is restrained by the spokes satisfies all conditions of a
tensile spoked wheel. When you say any wheel, you should stick to it. It
is also erroneous for you to say "a pretensioned wheel supports loads by
decreases in tension" when you know increases in tension over the top of the
wheel take place.


Your explanation on a pretensioned wheel is influential without resorting
to
the sites. I'll give it further thought.

That is a poor approach. Your thoughts should be guided by
the physical evidence, and not by what you assume the
physical evidence should be based on your mental ramblings.

I have not measured spoke tensile forces or rim compression as they are not
at critical levels in my wheels due to the technique of wheelbuilding I
advocate. The tensioning of spokes in others wheels is not relevant to my
method. I have no intrest in wheelbuilding techniques that produce a wheel
with demonstrable risk of failure. The unwarranted incessant contradiction
of my postings is evident of your mental state however.


I think this 95% shift may only occur in a grossly pre-tensioned wheel.
My methods do not require gross pre-tensioning so how similar, measured
results will be is questionable.

Wheels are linearly elastic, so the decrease tension of the
bottom spokes equal to 95% of the load will be the same
regardless of the the initial tension in spokes. (This is
required by Hooke's Law.)

Hookes law applies to solids and does not apply when components are taken
out of their elastic range, which is bounded by the limit of
proportionality. I do not feel that Hookes law should necessarily be
applied to a wheel due to the sliding movement evident from wear at the
spoke crossing. The use of a tied and soldered wheel I may have found more
acceptable. The crossing of spokes puts a bend in them, the relative
varience in tension of a pair of spokes means that each spoke has behaviour
approaching a damped spring. The crossing of the spokes generally reduces
the loading and unloading rate of the spoke which is thought to effect
fatigue progression. If all bottom spokes become loose when the load is
applied, the top spokes wholy(100%) take the load, the bottom spokes are not
functioning. But of course yours is a specious argument to support a
specious wheel.


The fact still remains that lateral and radial stability along with
reduced
spoke failures can be attained by pre-forming the spokes at their
crossing.

Please elaborate. The forces inside the wheel caused not
the external load can not be eliminated, only
re-distributed. How does your pre-forming change the force
distribution?

By making the kink at the crossing, the spoke takes the shortest possible
route(with crossed spokes) between rim and hub. This enables it to better
restrain the rim as tendancy for the rim to move out is countered more
positively than by a spoke which is left without the correct shaping.


Interestingly, you have laid out all the pieces on how
wheels support a load, you just have to put them together.
A load on a wheel causes a decrease in tension in the bottom
spokes almost equal to the applied load. The bottom spokes
must not completely slacken, or the wheel loses lateral
support. Therefore, the spokes in the bottom wheel must
have some pre-tension, to keep from slackening when a load
is applied. Since the greater the applied load, the more
tension is lost in the bottom spokes, higher loads require
more spoke pre-tension. In other words, the strength of the
wheel is directly related to the amount of static tension in
the spokes. Of course, there are practical limits to how
much static spoke tension a given wheel can stand, but in
general, a tighter wheel is a stronger wheel.


I did not say decrease in bottom spokes is nearly equal to the load. If I
ever talk about spoke tensions in relation to the general support of how the
wheel bears its load by force distribution as a whole, a call for vectors
would be in order. I'll repeat again read the subject heading " The
Basics of Wheel Alignment and Wheelbuilding", theory of how a wheel bears
its load was not warranted, your off topic. Where I agree or disagree with
you is not relevant to an improved wheelbuilding method.

Trevor

wrote in message
...
On Fri, 6 Aug 2004 07:35:16 +0100, "Trevor Jeffrey"
wrote:


wrote in message ...
On Fri, 6 Aug 2004 00:42:55 +1000, Weisse Luft
wrote:
.

But you're saying that the variation of the spoke load is
less. Is this a matter of both thick and thin spokes being
tensioned to X pounds and the thick one going to 0 pounds
of tension, a variation of X, while the more elastic thinner
spoke doesn't drop as far--say to 10 lbs tension--and
therefore has a smaller load range of X -10 instead of the
full range of X.

Presumably spokes last longer with this smaller load
variation. I'm hoping that I've managed to figure out what
you (and others) already understood, since it seems clearer
than waving my hands and declaring that losing all tension
is a bad thing.

Steels tested for this, have not shown it to be evident.
Reduction of magnitude of load variation may increase life of sample, but
the increase of tension before applying load variation does not show
benefits for component life.

TJ


Dear Trevor,

Actually, I wrote that, not Weisse Luft.

You may have misunderstood something here.

As far as I know, both the butted spokes with the thinner
midsection and the straight spokes would be tensioned to
the same force of X pounds of tension.

It's the increased elasticity of the thinner double-butted
spoke that reduces the variation of tension.

A wheel with infinitely thick spokes does not require pretensioning, so the
thicker spoke requires less tension than the thinner spoked wheel.
The materials elasticity does not change with section, I understand your
usage to mean its more stretchy.

When the thicker and therefore less elastic straight spokes
contract enough to go from X pounds to 0 pounds of tension,
they have experienced the full range of possible tension
variation.

A greater load would be required for the wheel with thicker spokes for them
to become loose.

In the same situation, the thinner and therefore more
elastic double-butted spokes start at the same X pounds of
tension, but do not relax to 0 pounds of tension. Their
range of variation is therefore smaller.

The situation is not the same because the thicker spokes make a stiffer
wheel with less deformity for the same load.


Again, both kinds of spokes began at the same tension in the
wheel. The difference is that the thick spokes will lose all
tension well before the thin spokes do.

No, because the thicker spoke has greater resilience, the rim will deform
less due to better constraint. The smaller rim deformation results in
lower tension loss in the low spokes.

Trevor

Trevor Jeffrey Wrote:
Mark McMaster wrote in message ...


Rolling resistance was not the issue that Thompson and
Dunlop were trying to address.

So what issues?
Patent spec. 10,990 10 June 1846 Robert William Thomson
"The nature of my said Invention consists in the application of
elastic
bearings round the tires of the wheels of carriages, for the purpose
of
lessening the power required to draw the carriages, rendering their
motion
easier and diminishing the noise they make when in motion."

Impossible? No. Impractical? In some cases. Pneumatic
tires for railroad wheels actually are in service in some
locations:

As I said.

(Note, the second web site has a reference to the added
rolling resistance caused by rubber tires as a disadvantage
to their use on railroad wheels.)

That would be the rolling resistance over a typical railroad wheel
running
on a purpose designed track and has minimal relationship to a bicycle
wheel
which can run over soft ground.




It appears that you are suffering from cognitive dissonance.
During discussions on wheel mechanics, you become agitated /


I really don't. Don't make false accusations.


It is still uneccasary and irrelevant, you only bring it up to
cause
diversion.

No, the ignoring direct data of wheel forces in determining
how wheel works is a diversion from finding the truth.
Again I ask - what objective evidence do you base your
beliefs on? If you have no evidence to support your
statements (and all other available evidence disputes it)
you must be wrong.

To say that force is transfered by the rim to the spokes to the hub was
not
something I thought needed explanation because the newsthread appeared
to
be about how to build a better wheel. Of which I put forward my
explanation of how I managed it. You on the other hand persist in
constantly going off topic on many different lines in an attempt to
discredit my postings.

Ah, but the available evidence shows that the bottom spokes
do lose tension when the wheel is loaded. How do guarantee
that the spokes don't become completely slack, as you have
said is required to maintain lateral stability, if the
spokes are pre-tensioned?

This is a bit garbled. I hope the following answers the question that
you
think you were asking. I have stated that a wheel's spokes do not
require
pre-tensioning to function. I have stated a wheel's spokes require a
modicum of tensioning during build, sufficient to prevent loose
spokes
under maximum load predicted by cornering and braking. I have also
stated
that the fear of a loose spoke is unfounded.

the

rim. This is because the rim acts as an arch and changes the
direction

of

load through 90deg to travel along that arch.

No, absolutely not. Neither an arch, nor any other static
structure, can eliminate a force vector component. Newton's
3rd law states that every action has equal and opposite
reaction. If a vertical force is applied to a structure,
there must be an equal and opposite vertical force to
support it. An arch can not make a vertical force
horizontal. There may be an additional horizontal force
generated (which again must have an equal and opposite force
to support it), but an arch can not make any force vector
disappear. This is basic freshman statics. I suggest you
review a pertinent text book.

And the load is transfered by the spokes is what I said, I did not go
into
detail because it depends on how much tension is in the spokes on the
predominant manner on exactly the way the load is transferred. Plus it
was
not relevant for my method to acertain the precise load values at any
one
moment. It being sufficient to know that the rotating wheel produces
cyclic
variation in the spokes, so that a spoke and its 'pair' will have
relative
changes in tension as they rotate. It is the relative changes in
tension
which move the spoke crossing in an out so as to cause the fatigue
failure
at the hub.


I don't know what you mean by asking if "the spokes are
adequately tensioned and not over-tensioned?". Spoke
components are made from linearly elastic materials (metals)
so as long as the spokes are adequately tensioned and do not
completely slacken, nor exceed their elastic limit, the
results are valid (and since there is little increase in
tension in any spokes when the wheel is loaded, it is
unlikely they will exceed their elastic limit.)

By over-tensioned, I mean that the tension within the spokes is liable
to
cause the rim to buckle due to excessive compression without adequate
lateral support. Buckling is the usual failure of long slim members
in
compression, my method not only addresses the problem of fatigue
failure at
the spoke heads, it also improves lateral stability and reduces rim
compression so allowing a more predictable wheel.



Is it also shown that the spokes take a
direct line and are not looped around each other. Unless these
conditions
are satisfied, it is improbable that the data would corespond to my
wheel
build. If you disagree, perhaps you may think it raises serious
doubt.

If you had actually looked at the data, you would see that
wheels both radially laced, and with crossed (interlaced)
spokes were examined. Again you are not doing your research.

I stated I had not examined the wesite. I have done my research.
Check the patent cited at the top of this posting.



If there is little increase in the tension in
the top spokes, there can be little increase in compression
in the top half of the rim, which means that there is little
rim compression transferred from the bottom half of the
rim. Therefore, the load on a wheel is not transferred

from the ground to the hub primarily by rim compression.

You make an assumption based on pre-conceived ideas and measurements
on
others wheels. My statements hold true for a wheel not
pre-tensioned.
So how does the load transfer between tyre and spokes if not by
compression?
Faries?

No, there are no assumptions. They are simply the logical
conclusions based on the data and known laws of nature.
So how is the load tranferred between tyre and spokes?



The magnitudes of the spoke tension changes have been
measured and calculated by many independent parties, who
have all discovered


What they set out to "discover"

The aim to discover how a bicycle wheel actually supports a
load. What are you trying to discover?

How to make the most reliable wheel, of which I have given my account
of my
method and why it is better. Why do you persist in going off topic?


How does pre-forming of the spokes at the crossing minimize
the pre-tensioning? The spokes at the bottom of the wheel
loose tension, regardless of the path they take from the hub
to the rim.

The pre-forming of the spokes reduces the frequency of fatigue failure
at
the hub. Without pre-forming the tension of the spokes required to
matched
the radial stability is much greater, resulting in excessive rim
compression
with the lateral instability that results.
The

It would not apply should the spokes be loose before loading, so
does not
apply to all tensile spoked wheels. To exclude some wheels because
they
are
not up to some sort of arbitary tension is not a valid argument to
support
the theory that the wheel is supported by a decrease in tension.

But if they are not up to adequate tension, then when the
bottom spokes slacken with load, they fail your test of
maintaining lateral stability. Therefore, any wheel which
remains stable must be pre-tensioned, and any wheel that is
pre-tensioned supports loads by decreases in tension.

A theory on wheel support is incorrect if it excludes those specious
wheels,
which although servicable, would not be normally acceptable for
service. To
say the rim is restrained by the spokes satisfies all conditions of a
tensile spoked wheel. When you say any wheel, you should stick to it.
It
is also erroneous for you to say "a pretensioned wheel supports loads
by
decreases in tension" when you know increases in tension over the top
of the
wheel take place.


Your explanation on a pretensioned wheel is influential without
resorting
to
the sites. I'll give it further thought.

That is a poor approach. Your thoughts should be guided by
the physical evidence, and not by what you assume the
physical evidence should be based on your mental ramblings.

I have not measured spoke tensile forces or rim compression as they are
not
at critical levels in my wheels due to the technique of wheelbuilding
I
advocate. The tensioning of spokes in others wheels is not relevant to
my
method. I have no intrest in wheelbuilding techniques that produce a
wheel
with demonstrable risk of failure. The unwarranted incessant
contradiction
of my postings is evident of your mental state however.


I think this 95% shift may only occur in a grossly pre-tensioned
wheel.
My methods do not require gross pre-tensioning so how similar,
measured
results will be is questionable.

Wheels are linearly elastic, so the decrease tension of the
bottom spokes equal to 95% of the load will be the same
regardless of the the initial tension in spokes. (This is
required by Hooke's Law.)

Hookes law applies to solids and does not apply when components are
taken
out of their elastic range, which is bounded by the limit of
proportionality. I do not feel that Hookes law should necessarily be
applied to a wheel due to the sliding movement evident from wear at
the
spoke crossing. The use of a tied and soldered wheel I may have found
more
acceptable. The crossing of spokes puts a bend in them, the relative
varience in tension of a pair of spokes means that each spoke has
behaviour
approaching a damped spring. The crossing of the spokes generally
reduces
the loading and unloading rate of the spoke which is thought to effect
fatigue progression. If all bottom spokes become loose when the load
is
applied, the top spokes wholy(100%) take the load, the bottom spokes
are not
functioning. But of course yours is a specious argument to support a
specious wheel.


The fact still remains that lateral and radial stability along with
reduced
spoke failures can be attained by pre-forming the spokes at their
crossing.

Please elaborate. The forces inside the wheel caused not
the external load can not be eliminated, only
re-distributed. How does your pre-forming change the force
distribution?

By making the kink at the crossing, the spoke takes the shortest
possible
route(with crossed spokes) between rim and hub. This enables it to
better
restrain the rim as tendancy for the rim to move out is countered more
positively than by a spoke which is left without the correct shaping.


Interestingly, you have laid out all the pieces on how
wheels support a load, you just have to put them together.
A load on a wheel causes a decrease in tension in the bottom
spokes almost equal to the applied load. The bottom spokes
must not completely slacken, or the wheel loses lateral
support. Therefore, the spokes in the bottom wheel must
have some pre-tension, to keep from slackening when a load
is applied. Since the greater the applied load, the more
tension is lost in the bottom spokes, higher loads require
more spoke pre-tension. In other words, the strength of the
wheel is directly related to the amount of static tension in
the spokes. Of course, there are practical limits to how
much static spoke tension a given wheel can stand, but in
general, a tighter wheel is a stronger wheel.


I did not say decrease in bottom spokes is nearly equal to the load.
If I
ever talk about spoke tensions in relation to the general support of
how the
wheel bears its load by force distribution as a whole, a call for
vectors
would be in order. I'll repeat again read the subject heading "
The
Basics of Wheel Alignment and Wheelbuilding", theory of how a wheel
bears
its load was not warranted, your off topic. Where I agree or disagree
with
you is not relevant to an improved wheelbuilding method.

Trevor

Do I understand your method as putting a "kink" in each spoke at the
exact crossing point, at the exact angle, and rotationally on the spoke
in the exact position.... before the spokes are assembled into the
wheel?

How exactly do you do that?

I am not arguing against the concept, just wondering how you go about
accomplishing it.

Further, it would be useful to know how you measure the benefit(s).

It seems that there are many methods used and contrary statements
made.
Sapim says don't bend the spoke elbow from it's factory position.
Bontrager Wheel Works and others seem to say that bending is not only
OK but should be done to attain alignment with the hub flange. The
only general agreement between the two most respected spoke
manufacturers (DT & Sapim) is that the use of spoke head washers is of
benefit.
I have built about 950 wheels. I am still learning. I am always
interested to learn how things can be done better... but I want
substantiated proof.


--
daveornee

On Sun, 8 Aug 2004 04:23:46 +0100, "Trevor Jeffrey"
wrote:


wrote in message
...
On Fri, 6 Aug 2004 07:06:12 +0100, "Trevor Jeffrey"
wrote:

[snip]

I have ridden a bare rim after tearing a tyre cased by
wheel collapse (constructed as instructed in JB's book) during sprinting.
It was the poor stability of this wheel made me want to investigate
further
on constructional techniques.

[snip]


Dear Trevor,

Could you explain this a bit more?

That is, what exactly does "wheel collapse" mean to you?
It sounds catastrophic, since it caused a torn tire.

Wheel buckled to lock up in frame pitching me to ground.

Did you somehow repair this wheel and continue riding on it
after removing the tire? Or was there a later experiment?

tyre was torn where rim joint had twisted, tyre not repairable and was
removed.
rim wsa partially straightened in drainage grid and front brake pulled to
one side as it could not be relaxed to a\llow for rim oscillations.

I assume, perhaps incorrectly, that you built a wheel to the
best of your ability to Jobst Brandt's suggestions and feel
that it had "poor stability" because it collapsed, not that
the wheel suffered from "poor stability" after it collapsed,
was repaired, and was ridden with no tire.

The wheel was constructed to the letter of the method suggested, it had
poor lateral stability and it collapsed during sprinting, this is self
evident.
TJ


Dear Trevor,

So it was a front wheel that failed during sprinting?

Front wheels are usually symmetrical and therefore
considerably stronger than dished rear wheels.

Front wheels typically bear less weight than rear wheels.

To steer, front wheels are free to swivel, unlike rear
wheels, which are fixed in the rear triangle.

Sprinting doesn't usually involve braking or turning.

So it doesn't seem likely that a front wheel with intact
spokes collapsed from any unusual forces on its own.

You don't mention any spoke damage, just a wheel collapse,
but my guess would be that a fatigued spoke happened to
break during a sprint (there are no unusual forces on a
front wheel in that situation), the out-of-true wheel then
jammed, and this jamming and the crash damaged the rim.

If this is what happened, the "lateral stability" might be a
matter of the number of spokes. Low-spoke-count wheels often
cannot be trued enough to spin in the frame when one spoke
breaks.

Carl Fogel

On Sun, 8 Aug 2004 07:27:05 +0100, "Trevor Jeffrey"
wrote:


wrote in message
...
On Fri, 6 Aug 2004 07:35:16 +0100, "Trevor Jeffrey"
wrote:


wrote in message ...
On Fri, 6 Aug 2004 00:42:55 +1000, Weisse Luft
wrote:
.

But you're saying that the variation of the spoke load is
less. Is this a matter of both thick and thin spokes being
tensioned to X pounds and the thick one going to 0 pounds
of tension, a variation of X, while the more elastic thinner
spoke doesn't drop as far--say to 10 lbs tension--and
therefore has a smaller load range of X -10 instead of the
full range of X.

Presumably spokes last longer with this smaller load
variation. I'm hoping that I've managed to figure out what
you (and others) already understood, since it seems clearer
than waving my hands and declaring that losing all tension
is a bad thing.

Steels tested for this, have not shown it to be evident.
Reduction of magnitude of load variation may increase life of sample, but
the increase of tension before applying load variation does not show
benefits for component life.

TJ


Dear Trevor,

Actually, I wrote that, not Weisse Luft.

You may have misunderstood something here.

As far as I know, both the butted spokes with the thinner
midsection and the straight spokes would be tensioned to
the same force of X pounds of tension.

It's the increased elasticity of the thinner double-butted
spoke that reduces the variation of tension.

A wheel with infinitely thick spokes does not require pretensioning, so the
thicker spoke requires less tension than the thinner spoked wheel.
The materials elasticity does not change with section, I understand your
usage to mean its more stretchy.

When the thicker and therefore less elastic straight spokes
contract enough to go from X pounds to 0 pounds of tension,
they have experienced the full range of possible tension
variation.

A greater load would be required for the wheel with thicker spokes for them
to become loose.

In the same situation, the thinner and therefore more
elastic double-butted spokes start at the same X pounds of
tension, but do not relax to 0 pounds of tension. Their
range of variation is therefore smaller.

The situation is not the same because the thicker spokes make a stiffer
wheel with less deformity for the same load.


Again, both kinds of spokes began at the same tension in the
wheel. The difference is that the thick spokes will lose all
tension well before the thin spokes do.

No, because the thicker spoke has greater resilience, the rim will deform
less due to better constraint. The smaller rim deformation results in
lower tension loss in the low spokes.

Trevor


Dear Trevor,

I'm puzzled by a number of things that you write.

What do you mean, for example, when you say that the thicker
spoke has greater resilience? As I understand it, a thicker
spoke shows less elastic deformation under the same tension
as a thinner spoke.

Carl Fogel

The Brandt book says butted spokes stretch more in the middle and less at
the ends, resulting in less metal fatigue in these vulnerable areas.


wrote in message
...
On Sun, 8 Aug 2004 07:27:05 +0100, "Trevor Jeffrey"
wrote:


wrote in message
...
On Fri, 6 Aug 2004 07:35:16 +0100, "Trevor Jeffrey"
wrote:


wrote in message ...
On Fri, 6 Aug 2004 00:42:55 +1000, Weisse Luft
wrote:
.

But you're saying that the variation of the spoke load is
less. Is this a matter of both thick and thin spokes being
tensioned to X pounds and the thick one going to 0 pounds
of tension, a variation of X, while the more elastic thinner
spoke doesn't drop as far--say to 10 lbs tension--and
therefore has a smaller load range of X -10 instead of the
full range of X.

Presumably spokes last longer with this smaller load
variation. I'm hoping that I've managed to figure out what
you (and others) already understood, since it seems clearer
than waving my hands and declaring that losing all tension
is a bad thing.

Steels tested for this, have not shown it to be evident.
Reduction of magnitude of load variation may increase life of sample,
but
the increase of tension before applying load variation does not show
benefits for component life.

TJ


Dear Trevor,

Actually, I wrote that, not Weisse Luft.

You may have misunderstood something here.

As far as I know, both the butted spokes with the thinner
midsection and the straight spokes would be tensioned to
the same force of X pounds of tension.

It's the increased elasticity of the thinner double-butted
spoke that reduces the variation of tension.

A wheel with infinitely thick spokes does not require pretensioning, so
the
thicker spoke requires less tension than the thinner spoked wheel.
The materials elasticity does not change with section, I understand your
usage to mean its more stretchy.

When the thicker and therefore less elastic straight spokes
contract enough to go from X pounds to 0 pounds of tension,
they have experienced the full range of possible tension
variation.

A greater load would be required for the wheel with thicker spokes for
them
to become loose.

In the same situation, the thinner and therefore more
elastic double-butted spokes start at the same X pounds of
tension, but do not relax to 0 pounds of tension. Their
range of variation is therefore smaller.

The situation is not the same because the thicker spokes make a stiffer
wheel with less deformity for the same load.


Again, both kinds of spokes began at the same tension in the
wheel. The difference is that the thick spokes will lose all
tension well before the thin spokes do.

No, because the thicker spoke has greater resilience, the rim will deform
less due to better constraint. The smaller rim deformation results in
lower tension loss in the low spokes.

Trevor


Dear Trevor,

I'm puzzled by a number of things that you write.

What do you mean, for example, when you say that the thicker
spoke has greater resilience? As I understand it, a thicker
spoke shows less elastic deformation under the same tension
as a thinner spoke.

Carl Fogel