The Basics of Wheel Alignment and Wheelbuilding

You would think that the spoke manufacturers would have some sort of
opinion regarding "stress relieving", and would make that known. They
don't want their spokes to bread while in service more than anyone
else.

On Sat, 31 Jul 2004 00:19:11 -0500, Tim McNamara
wrote:

Prove him wrong. Put
up or shut up. Frankly, jim beam old buddy old pal, I don't think you
have the stuff.

I think you are on the right track but good science doesn't work that
way. The hypothesis needs to be proven.

wrote:

None of these objections, as I recall, were meant to cast
any doubt on Mike Prime's aluminum plate test itself, which
was not undertaken to address the stainless steel spoke
question and seems like a reasonable test to bring up. They
were raised to point out that the two situations may differ
in significant ways (and were also raised probably for the
joy of quibbling, not that we ever see any of that on
rec.bicycles.tech).

Sure they differ. It does show that the metallurgical phenomenon
exists and is not just something Jobst made up without justification,
which is what some people seem to be arguing.

Unless you can get someone to do tests on actual spokes
that's probably as good as you can get. I don't know what
tests would prove it conclusively, perhaps sectioning and
electron micrography. There are a variety of materials tests
for flaws and stress cracks which I am no expert on, but
most of them are probably designed for much bigger pieces
than a spoke (I suspect eddy current testing is like that).

I often wonder whether my wavering on this matter resembles
what I had to endure with people debating who wrote
Shakespeare. I'm not sure who's right about spoke squeezing,
so I long for a site that patiently goes through the details
for the layman in the way that this site explains literary
matters:

http://shakespeareauthorship.com

I think, even if there were workable tests, if someone tried to
write such a document it would have to teach the reader basic
physics, metallurgy, and mechanical engineering. At least
with Shakespeare, most readers understand the basics like
dates, tenses and handwriting, even if they don't know the
detailed issues about Elizabethan manuscripts, printing, and
the social position of playwrights.

Even so, I'm sure there is an Oxfordian site somewhere that tries
to refute all the arguments on shakespeareauthorship.com. To your
trained eyes, its arguments are transparently blowing smoke,
but to a layman's, it may not be so. I see similar things happening
here on r.b.tech when people talk about spokes.

The last person whom I bored to tears about spokes raised an
interesting question. If spoke-squeezing works, either by
relieving stress or by other methods, and makes spokes
practically immortal, how soon should unsqueezed spokes
break? That is, when did I predict that the unsqueezed
spokes would fail?

My muttered "sooner" was dismissed as being a bit imprecise.
I'd mentioned that some spoke squeezers claim over 50,000
miles on failure-free spokes, so my tormentor kept asking me
when he should expect his unsqueezed spokes to fail--1,000
miles, 5,000, 10,000, or even 25,000 miles?

He relented when I promised to pose the question here, so
perhaps someone will speculate on how long the spokes on
what everyone agrees is an otherwise properly built wheel
should last if not squeezed.

It's completely unanswerable as is, because we don't know
anything about the use of the wheel - the weight of the rider,
on-road or off-road, rough pavement? I wouldn't trust any
answer that tried to derive this from first principles.
If the use is light enough and the build was fairly good
apart from squeezing, maybe the wheel won't break. I am not
a professional wheelbuilder so I don't have enough base
knowledge to tell you.

However, there is a substantial weight of experience. It is
very common to see posts in r.b.tech from people who are
breaking spokes on stock wheels on new bikes. Most new
good-quality bikes these days use stainless steel spokes that
are strong enough for the job. The likely suspect is an
inadequate wheelbuild. I don't have much idea how this
translates into mileage, but when people break a lot of
spokes in their wheels, I think it happens early. If a
wheel survives 10,000 miles, it isn't going to break half
the spokes at 11,000.

JB may say he corrects the spoke line, and then leaves the most
important diversion, at the spoke crossing, to take care of itself. The
pre-shaping of the crossing point before spoke tensioning is the most
beneficial time spent in the construction of a wheel. It also saves on
component cost as the cheapest available parts may be used with success.
Over tensioning to correct spoke line stinks. All it is, is pre-loading.
Brandt advocates ought to apply the same logic to bridge building,
preloading to just under the point of collapse, and then think. There is
no argument that bicycle wheels are a special circumstance, the bicycle is
what brought along much of 19&20C engineering.
Wheels are made of metal with their rims in compression and spokes in
tension. Increase spoke tension and rim compression increases. Increase
load on bicycle and rim commpression increases. There is a maximum
compressive force that each rim can sustain without lateral support.
Pre-loading rims therefore is unacceptable. The potential consequences of a
buckled wheel compared to the loss of function of one spoke are too great on
my planet.
The reason why "stress releiving" results in a lower spoke failure is
that it will partially correct the bend of the spoke at the crossing. Much
better to specifically aim for this result. If the deviation at the
crossing is not made, the crossing point will move in and out relative to
the hub as the loaded wheel is rotated. This causes the fatigue failure of
the spoke at the hub so often reported.
If the preforming of the spoke at it's crossing is performed, the risk
of spoke loss due to fatigue failure is less than the method of
overtensioning. the MTBF is greater. Wheelbuilding is simpler, easier and
less stressfull. No rim failures is construction or on the road. Lateral
stability is improved with lower tension. The spokes act as the tensile
members the are designed to be and not as springs.
The smaller the angular deviation of the crossing the more likely you
are to get away with not pre-forming the spoke. This would explain the
popularity of x3 and x4 on a front wheel and also the use of large flange
hubs. Each of these methods can reduce the angular displacement at the
crossing so lessening the repeated bending of the spoke at the hub. My
preferred method of construction is uibtable for all rims and standard
spokes.
TJ

Trevor Jeffrey wrote:

...No rim failures is construction or on the road....

Huh?

--
Tom Sherman – Quad City Area

Tom Sherman wrote in message ...
Trevor Jeffrey wrote:

...No rim failures is construction or on the road....

Huh?

I notice reports that rims have 'tacoed' during construction and in use. I
believe this is to avoid the term buckled (a form of failure).
TJ

Trevor Jeffrey wrote:

Tom Sherman wrote in message ...

Trevor Jeffrey wrote:


...No rim failures is construction or on the road....

Huh?


I notice reports that rims have 'tacoed' during construction and in use. I
believe this is to avoid the term buckled (a form of failure).

So the above should have read, "No rim failures IN construction or on
the road"?

--
Tom Sherman – Quad City Area

Tom Sherman wrote in message ...

Trevor Jeffrey wrote:


...No rim failures is construction or on the road....


Huh?


I notice reports that rims have 'tacoed' during construction and in use.
I
believe this is to avoid the term buckled (a form of failure).


So the above should have read, "No rim failures IN construction or on
the road"?

Yes, seems a bit of a wild mistype must be a comp. glitch.
Thank you.
TJ

Tim McNamara wrote in message ...

oil. My spoke nipples do not unwind in use, despite being 215 lbs and
riding 32 spoke wheels 6,000 to 7,000 miles a year. The reason for
this is not using something to glue the nipples and spokes together,
but using adeqate tension in the first place. Stuff like linseed oil
and Spoke Prep just covers for a badly built wheel.

Hmmm, this conversation seems like old times.

The use of any oil will assist in the prevention of a nipple shaking
loose, a drying oil just happens to be the most successful in this
application, i.e. a wheel not overtensioned. The wheel construction is how
I describe and not what you ride. Your conversation is repeated because you
do not appear to take on board what I have wrote. Adequate tension is
accomplished when the wheel remains laterally stable under load. Further
tension unnecessarily reduces the available load capacity of the rim and so
of the wheel.
TJ

Benjamin Weiner wrote:
wrote:


None of these objections, as I recall, were meant to cast
any doubt on Mike Prime's aluminum plate test itself, which
was not undertaken to address the stainless steel spoke
question and seems like a reasonable test to bring up. They
were raised to point out that the two situations may differ
in significant ways (and were also raised probably for the
joy of quibbling, not that we ever see any of that on
rec.bicycles.tech).


Sure they differ. It does show that the metallurgical phenomenon
exists and is not just something Jobst made up without justification,
which is what some people seem to be arguing.

Unless you can get someone to do tests on actual spokes
that's probably as good as you can get. I don't know what
tests would prove it conclusively, perhaps sectioning and
electron micrography. There are a variety of materials tests
for flaws and stress cracks which I am no expert on, but
most of them are probably designed for much bigger pieces
than a spoke (I suspect eddy current testing is like that).


I often wonder whether my wavering on this matter resembles
what I had to endure with people debating who wrote
Shakespeare. I'm not sure who's right about spoke squeezing,
so I long for a site that patiently goes through the details
for the layman in the way that this site explains literary
matters:


http://shakespeareauthorship.com


I think, even if there were workable tests, if someone tried to
write such a document it would have to teach the reader basic
physics, metallurgy, and mechanical engineering. At least
with Shakespeare, most readers understand the basics like
dates, tenses and handwriting, even if they don't know the
detailed issues about Elizabethan manuscripts, printing, and
the social position of playwrights.

Even so, I'm sure there is an Oxfordian site somewhere that tries
to refute all the arguments on shakespeareauthorship.com. To your
trained eyes, its arguments are transparently blowing smoke,
but to a layman's, it may not be so. I see similar things happening
here on r.b.tech when people talk about spokes.


The last person whom I bored to tears about spokes raised an
interesting question. If spoke-squeezing works, either by
relieving stress or by other methods, and makes spokes
practically immortal, how soon should unsqueezed spokes
break? That is, when did I predict that the unsqueezed
spokes would fail?


My muttered "sooner" was dismissed as being a bit imprecise.
I'd mentioned that some spoke squeezers claim over 50,000
miles on failure-free spokes, so my tormentor kept asking me
when he should expect his unsqueezed spokes to fail--1,000
miles, 5,000, 10,000, or even 25,000 miles?


He relented when I promised to pose the question here, so
perhaps someone will speculate on how long the spokes on
what everyone agrees is an otherwise properly built wheel
should last if not squeezed.


It's completely unanswerable as is, because we don't know
anything about the use of the wheel - the weight of the rider,
on-road or off-road, rough pavement? I wouldn't trust any
answer that tried to derive this from first principles.
If the use is light enough and the build was fairly good
apart from squeezing, maybe the wheel won't break. I am not
a professional wheelbuilder so I don't have enough base
knowledge to tell you.

However, there is a substantial weight of experience. It is
very common to see posts in r.b.tech from people who are
breaking spokes on stock wheels on new bikes. Most new
good-quality bikes these days use stainless steel spokes that
are strong enough for the job. The likely suspect is an
inadequate wheelbuild. I don't have much idea how this
translates into mileage, but when people break a lot of
spokes in their wheels, I think it happens early. If a
wheel survives 10,000 miles, it isn't going to break half
the spokes at 11,000.

you raise some very interesting points.

first is, does stress relief exist? yes, but the /real/ question is
whether it's relevant to this application. jobst clearly didn't make it
up, but he doesn't seem to understand it either. just like he used the
phenomenon of elastohydrodynamic separation as an explanation of why
headsets brinelled and hubs didn't. fact is, e.h.d.s. is not operative
in hubs at normal roads speeds, but his apparent ignorance of that fact
didn't stop him bullying folks here about it for years. similarly, he
explained stress relief in terms of deformation without work hardening,
a phenomenon that is present in mild steels, and cites such material
behavior in his book. unfortunately, that phenomenon is not known to
exist in stainless steels. perhaps that's why he doesn't understand why
the first stress/strain graph shown in his book is incorrect. the fact
that that graph is not replicated in the "real world" stress/strain
graphs he obtains from actual spoke testing as shown in the back of his
book does not appear to have registered.

second is fatigue testing. "the book" sets out a number of topics, and
proceeds to explore them in a number of ways. his tied & soldered
spokes testing is an example of where he has actually done quantitative
testing and publishes results. his "stress relief" theory on the other
hand is entirely subjective, amounting to "i say it works". he offers
no quantitative substantiation for that claim whatsoever. sure,
pointing at the phenomenon of metallurgical stress relief may sound
plausible, but his kind of usage is not anything i've ever seen cited in
literature for this kind of application. it would make millions of man
hours of research into fatigue over the last 100+ years irrelevant if
all we had to do was give a component a quick tweak in order to give it
infinite fatigue life characteristics. the coincidence of his theory
appearing at about the same time as real world materials advances like
vacuum degassed stainless steels becoming available in quantity is not
something lost on jobst. he even alludes to their existence in his
book, but tellingly fails to pursue their relevance or importance.

third, and related to the above, is spoke brand. this is most
definitely relevant. i have a large collection of broken spokes
collected from various wheels of friends and acquaintances over the last
few years. with the exception of those that have been physically
damaged thereby initiating fatigue at this point, they are all "unknown"
brands. in a highly competitive market, saving even a couple of bucks
on some no-name spokes on stock wheels where no one knows or cares what
they are is going to help profitability. the usual explanation here on
r.b.t. is that these wheels were "not stress relieved". failure to see
the relevance of the material quality employed in building that wheel
may not be convenient to "the theory", but it sure is a substantial blow
to credibility.

lastly, you mention early failures. this is actually consistent with a
lot of real world fatigue applications, automotive gearboxes being
another example. it's often called "the bath tub curve", where the
probability of failure starts comparatively high, rapidly drops, then
after an extended period, starts to climb again so the line on the graph
is a long shallow "u" like a bath tub. if the component can get through
the first few hours of use, its probability of survival increase
substantially. indeed, a lot of s/n curves show scatter at the low
cycle end of the graph for this reason and very low cycle failures are
often ignored.