SAPIM Spoke FAtigue Estimate

Johan Bornman said:

In my hand I have a SAPIM brochure - Trust in SAPIM Spokes.

On the second-last page of the brochure, SAPIM has a graph showing the
estimated spoke life in wheel revolutions. The company's standard
double-butted spoke, the Race, has an estimated life of just under 1
million revolutions.

Let's say 1 million for argument sake, and that a wheel revolution
translates into two meters on the road. Therefore, the spoke life is
only 2 million meters or, 2000 kms. Not exactly something to brag
about.

that is machine testing, not wheel testing. the machine loads from
0-80kg each cycle. what does a wheel load on each cycle?

Quoted message said:

Interestingly, but as an aside to this inaccurate estimate by SAPIM,
the company's CD-Ray product, a 2,3mm wide bladed spoke, has an
estimated life of 3,5 million "Wheel Revolutions (in cycles), as SAPIM
puts it.

how much bending moment can a skinny bladed spoke exert compared to a
fat straight gauge spoke?

Quoted message said:

Why would the company think that it's bladed spoke will last longer
than the round one?

they don't "think", they test. if tests show one lasts longer than the
other...

Quoted message said:

Since diameter is a difficult comparison in this
case, perhaps weight is. The bladed spoke has a weight index of 278,
whereas the round one 360. The index btw, is my invention, they weigh
278g per sample length per X number of spokes.

what does weight have to do with it other than being a side-effect of
having more material?

Johan Bornman said:

In my hand I have a SAPIM brochure - Trust in SAPIM Spokes.

On the second-last page of the brochure, SAPIM has a graph showing the
estimated spoke life in wheel revolutions. The company's standard
double-butted spoke, the Race, has an estimated life of just under 1
million revolutions.

Let's say 1 million for argument sake, and that a wheel revolution
translates into two meters on the road. Therefore, the spoke life is
only 2 million meters or, 2000 kms. Not exactly something to brag
about.

Don't you realize that you have just committed a most heinous crime - you dared to question Impressive, Big, Round Numbers Used In Marketing!

On 7 Feb 2007 06:07:53 -0800, "Johan Bornman" <[email hidden]>

Quoted message said:

Why would the company think that it's bladed spoke will last longer
than the round one?

Because the two spokes have different metallurgy. The production
process for the CX-Ray is much more involved than the basic "take a
bit of wire and bang one end into a mushroom" of a cheap straight
guage spoke.

Disregarding the Sapim "hype", the sheer number of boutique wheels
(HED, Corima, Xtreme) which are built with CX-Rays confirms its
position as the uber-spoke

Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary

On 7 Feb 2007 06:07:53 -0800, "Johan Bornman" <[email hidden]>

Quoted message said:

In my hand I have a SAPIM brochure - Trust in SAPIM Spokes.

On the second-last page of the brochure, SAPIM has a graph showing the
estimated spoke life in wheel revolutions. The company's standard
double-butted spoke, the Race, has an estimated life of just under 1
million revolutions.

Let's say 1 million for argument sake, and that a wheel revolution
translates into two meters on the road. Therefore, the spoke life is
only 2 million meters or, 2000 kms. Not exactly something to brag
about.

Interestingly, but as an aside to this inaccurate estimate by SAPIM,
the company's CD-Ray product, a 2,3mm wide bladed spoke, has an
estimated life of 3,5 million "Wheel Revolutions (in cycles), as SAPIM
puts it.

Why would the company think that it's bladed spoke will last longer
than the round one? Since diameter is a difficult comparison in this
case, perhaps weight is. The bladed spoke has a weight index of 278,
whereas the round one 360. The index btw, is my invention, they weigh
278g per sample length per X number of spokes.

Johan Bornman

Dear Johan,

Your question has come up before--it would be nice if Sapim would
include a description of its testing.

The Sapim spoke fatigue tests must use exaggerated stress cycles
because it takes literally years to break spokes in continuous testing
under ordinary low stress cycles--no spoke manufacturer sells spokes
that are expected to fail in only 2,000 km of normal riding.

In the study below, measured road-test spoke-stress ranged from only
20 to 150 MPa. It took months to break 76 test spokes with continuous
10-cycle-per-second testing at 174 to 501 MPa:

"In 1984 and 1985, fatigue tests on stainless steel bicycle spokes
were carried out for Wheelsmith, Inc. at Stanford University. Constant
cycle tests were conducted with pre-tensioning stresses of 174 MPa,
250 MPa, 343 MPa, 347 MPa, 424 MPa, and 501 MPa. . . . In 68 spokes
the failure occurred at the cold-worked elbow; in the remaining 8
spokes the failure occurred at the threads."

"The smallest stress cycle in the fatigue tests was 174 MPa, whereas
the stress range from the road test data was 20 MPa to 150 MPa. Hence,
the fatigue data was extrapolated to the low stress range. (To have
tested a single sample at 40 MPa would have required over a year of
continuous testing at 10 cycles per second, and an unwarranted use of
facilities.)"

http://www.duke.edu/~hpgavin/papers/HPGavin-Wheel-Paper.pdf

Ten stress cycles per second for a spoke on a 700c wheel is roughly 45
mph. It's also 315,360,000 cycles per year, roughly 630,000 km or
380,000 miles.

It's likely that those 1984 spokes were significantly less durable
than modern spokes.

Cheers,

Carl Fogel

Quoted message said:

Dear Johan,

Your question has come up before--it would be nice if Sapim would
include a description of its testing.

The Sapim spoke fatigue tests must use exaggerated stress cycles
because it takes literally years to break spokes in continuous testing
under ordinary low stress cycles--no spoke manufacturer sells spokes
that are expected to fail in only 2,000 km of normal riding.

I have no doubt that it is an exaggerated test cycle. But don't they
know in marketing hype one doesn't cite exaggerated examples, but best
case scenarios. I have SAPIM-built wheels which have done closer to 40
000 kms. Why would a company misrepresent itself so much? I don't
understand and I don't suppose there is a rational answer for this.

JB

Jim Beam said:

what does weight have to do with it other than being a side-effect of
having more material?

Everything, the more weight for a given length, the more material. I
assume (with confidence) that they use the same material - 18/8
stainless steel, as the brochure states.

JB

On 7 Feb 2007 11:48:26 -0800, "Johan Bornman" <[email hidden]>

Quoted message said:

Quoted message said:

Dear Johan,

Your question has come up before--it would be nice if Sapim would
include a description of its testing.

The Sapim spoke fatigue tests must use exaggerated stress cycles
because it takes literally years to break spokes in continuous testing
under ordinary low stress cycles--no spoke manufacturer sells spokes
that are expected to fail in only 2,000 km of normal riding.

I have no doubt that it is an exaggerated test cycle. But don't they
know in marketing hype one doesn't cite exaggerated examples, but best
case scenarios. I have SAPIM-built wheels which have done closer to 40
000 kms. Why would a company misrepresent itself so much? I don't
understand and I don't suppose there is a rational answer for this.

JB

Dear Johann,

I doubt that Sapim thinks that it's misrepresenting itself.

Sorry that I misunderstood whatever you're complaining about.

Cheers,

Carl Fogel

Johan Bornman said:

Jim Beam said:

what does weight have to do with it other than being a side-effect of
having more material?

Everything, the more weight for a given length, the more material.

weight is not known to be a factor in fatigue unless it affects loading
stress in some way.

Quoted message said:

I
assume (with confidence) that they use the same material - 18/8
stainless steel, as the brochure states.

JB

Johan Bornman said:

Quoted message said:

Dear Johan,

Your question has come up before--it would be nice if Sapim would
include a description of its testing.

The Sapim spoke fatigue tests must use exaggerated stress cycles
because it takes literally years to break spokes in continuous testing
under ordinary low stress cycles--no spoke manufacturer sells spokes
that are expected to fail in only 2,000 km of normal riding.

I have no doubt that it is an exaggerated test cycle. But don't they
know in marketing hype one doesn't cite exaggerated examples, but best
case scenarios. I have SAPIM-built wheels which have done closer to 40
000 kms. Why would a company misrepresent itself so much? I don't
understand and I don't suppose there is a rational answer for this.

there /is/ a rational answer for this - almost all fatigue testing is
done on an accelerated basis. since that's standard practice, their
reporting is simply consistent with standard practice.

jim beam said:

Quoted message said:

Jim Beam writes:

Quoted message said:

Quoted message said:

what does weight have to do with it other than being a side-effect of
having more material?

Quoted message said:

Johan B wrote: Everything, the more weight for a given length, the more material.

Jim Beam wrote: weight is not known to be a factor in fatigue unless it affects loading
stress in some way.

Johan now says: OK, let me explain why I brought weight into it in the
first place.

1) Sapim Race spokes have a "Wheel Revolutions" limit of 1 000 000
revolutions.
2) Sapim CX-Ray Spokes have a "Wheel Revolutions" limit of 3 500 000
revolutions.
3) They're both made of 18/8 stainless steel.
4) The CX-Ray spoke differs from the Race spoke in that it is a)
flattened and b) has less material for a given length (deducted from
the fact that they WEIGH less than an equivalent length Race spoke).

Thus, all things being equal, a thinner, flattened spoke has a longer
fatigue life than a thicker, round spoke.

We now have two factors that could contribute to the greater fatigue
life - the flattening process or the fact that the shaft is more
flexible (deduced from its relative weight).

There, does that make sense?

JB

jim beam said:

Johan Bornman said:

Quoted message said:

Dear Johan,

Quoted message said:

Quoted message said:

Your question has come up before--it would be nice if Sapim would
include a description of its testing.

Quoted message said:

Quoted message said:

The Sapim spoke fatigue tests must use exaggerated stress cycles
because it takes literally years to break spokes in continuous testing
under ordinary low stress cycles--no spoke manufacturer sells spokes
that are expected to fail in only 2,000 km of normal riding.

Quoted message said:

I have no doubt that it is an exaggerated test cycle. But don't they
know in marketing hype one doesn't cite exaggerated examples, but best
case scenarios. I have SAPIM-built wheels which have done closer to 40
000 kms. Why would a company misrepresent itself so much? I don't
understand and I don't suppose there is a rational answer for this.

there /is/ a rational answer for this - almost all fatigue testing is
done on an accelerated basis. since that's standard practice, their
reporting is simply consistent with standard practice.- Hide quoted text -

- Show quoted text -

You miss the point, being scientifically rational doesn't make sense
in this brochure. It is intended for consumers who can quickly do the
sums and discover that SAPIM kind of suggests a useful life of 1 000
kms for wheels built with its spokes. A good copywriter with the
company's interest at heart would have phrased the exercise completely
differently.

Johan Bornman

Johan Bornman said:

Thus, all things being equal, a thinner, flattened spoke has a longer
fatigue life than a thicker, round spoke.

We now have two factors that could contribute to the greater fatigue
life - the flattening process or the fact that the shaft is more
flexible (deduced from its relative weight).

The ends of the spoke have the same shape and size so it isn't
surprising that spoke with the thinner center section (cross sectional
area) outlasts the thicker one. In practice the thinner spoke will see
a lower stress cycle on the ends, because the center will stretch more
easily.

I don't agree with the way Sapim presented the data... with too little
explaination. But then I never like ads... there are always so many
claims made and so much left out.

Quoted message said:

"In 1984 and 1985, fatigue tests on stainless steel bicycle spokes
were carried out for Wheelsmith, Inc. at Stanford University. Constant
cycle tests were conducted with pre-tensioning stresses of 174 MPa,
250 MPa, 343 MPa, 347 MPa, 424 MPa, and 501 MPa. . . . In 68 spokes
the failure occurred at the cold-worked elbow; in the remaining 8
spokes the failure occurred at the threads."

"The smallest stress cycle in the fatigue tests was 174 MPa, whereas
the stress range from the road test data was 20 MPa to 150 MPa. Hence,
the fatigue data was extrapolated to the low stress range. (To have
tested a single sample at 40 MPa would have required over a year of
continuous testing at 10 cycles per second, and an unwarranted use of
facilities.)"

http://www.duke.edu/~hpgavin/papers/HPGavin-Wheel-Paper.pdf

Ten stress cycles per second for a spoke on a 700c wheel is roughly 45
mph. It's also 315,360,000 cycles per year, roughly 630,000 km or
380,000 miles.

It's likely that those 1984 spokes were significantly less durable
than modern spokes.

FWIW, Jobst is often quoted disparaging the durability
of older spokes, I think he meant spokes a lot older than
1984. Like 1960s or 1970s spokes. Once upon a time
stainless spokes were pretty rare (and I don't know if they
were all good either). By the mid 80s people might likely
have been building with DT (or Wheelsmith?) stainless
spokes fairly similar to today's. I would guess that a couple
of the grotty old Mavic wheels in the picture I posted to
the Finite Element thread are from the 80s, (red/gold Mavic
sticker era) and they have nice DT stainless spokes.
Time has not been as kind to the spoke eyelets.

Ben

Johan Bornman said:

jim beam said:

Johan Bornman said:

> Dear Johan,
> Your question has come up before--it would be nice if Sapim would
> include a description of its testing.
> The Sapim spoke fatigue tests must use exaggerated stress cycles
> because it takes literally years to break spokes in continuous testing
> under ordinary low stress cycles--no spoke manufacturer sells spokes
> that are expected to fail in only 2,000 km of normal riding.
I have no doubt that it is an exaggerated test cycle. But don't they
know in marketing hype one doesn't cite exaggerated examples, but best
case scenarios. I have SAPIM-built wheels which have done closer to 40
000 kms. Why would a company misrepresent itself so much? I don't
understand and I don't suppose there is a rational answer for this.

there /is/ a rational answer for this - almost all fatigue testing is
done on an accelerated basis. since that's standard practice, their
reporting is simply consistent with standard practice.- Hide quoted text -

- Show quoted text -

You miss the point, being scientifically rational doesn't make sense
in this brochure.

it makes more sense than being scientifically irrational or making
claims like "our spokes last forever if you don't use them", which is
basically where you end up if you exclude presentation of normal data.

Quoted message said:

It is intended for consumers who can quickly do the
sums and discover that SAPIM kind of suggests a useful life of 1 000
kms for wheels built with its spokes.

see above.

Quoted message said:

A good copywriter with the
company's interest at heart would have phrased the exercise completely
differently.

bottom line, while /you/ may not appreciate the format, the fact is,
sapim are the only ones that dare to present fatigue data. that should
tell you more than anything else.

Ron Ruff said:

Johan Bornman said:

Thus, all things being equal, a thinner, flattened spoke has a longer
fatigue life than a thicker, round spoke.

We now have two factors that could contribute to the greater fatigue
life - the flattening process or the fact that the shaft is more
flexible (deduced from its relative weight).

The ends of the spoke have the same shape and size so it isn't
surprising that spoke with the thinner center section (cross sectional
area) outlasts the thicker one. In practice the thinner spoke will see
a lower stress cycle on the ends, because the center will stretch more
easily.

but they don't fatigue in the center. skinnier section however does
produce a much lower bending moment on the elbow - the point where it
does break.

Quoted message said:

I don't agree with the way Sapim presented the data... with too little
explaination. But then I never like ads... there are always so many
claims made and so much left out.

yes, there's a good deal left out - but in this case, it's good stuff
about longevity, not bad. if criticism is due, it's for not being bold
enough, not for daring to present data when no one else will.

Quoted message said:

Quoted message said:

Quoted message said:

>> Dear Johan,
>> Your question has come up before--it would be nice if Sapim would
>> include a description of its testing.
>> The Sapim spoke fatigue tests must use exaggerated stress cycles
>> because it takes literally years to break spokes in continuous testing
>> under ordinary low stress cycles--no spoke manufacturer sells spokes
>> that are expected to fail in only 2,000 km of normal riding.

Quoted message said:

Quoted message said:

Quoted message said:

> I have no doubt that it is an exaggerated test cycle. But don't they
> know in marketing hype one doesn't cite exaggerated examples, but best
> case scenarios. I have SAPIM-built wheels which have done closer to 40
> 000 kms. Why would a company misrepresent itself so much? I don't
> understand and I don't suppose there is a rational answer for this.

jim beam said:

Quoted message said:

Quoted message said:

there /is/ a rational answer for this - almost all fatigue testing is
done on an accelerated basis. since that's standard practice, their
reporting is simply consistent with standard practice.-

Quoted message said:

Johan Bornman said:

You miss the point, being scientifically rational doesn't make sense
in this brochure.

jim beam said:

it makes more sense than being scientifically irrational or making
claims like "our spokes last forever if you don't use them", which is
basically where you end up if you exclude presentation of normal data.

Quoted message said:

Johan Bornman said:

It is intended for consumers who can quickly do the
sums and discover that SAPIM kind of suggests a useful life of 1 000
kms for wheels built with its spokes.

Quoted message said:

Johan Bornman said:

A good copywriter with the
company's interest at heart would have phrased the exercise completely
differently.

jim beam said:

bottom line, while /you/ may not appreciate the format, the fact is,
sapim are the only ones that dare to present fatigue data. that should
tell you more than anything else.

Maybe.
Or were those numbers pulled out of the air? "2000k lifetime" is
nonsensical to anyone with familiarity. But any ad writer would eagerly
write "one million cycles" for any product - especially if he weren't
burdened by knowledge of bikes or spokes.

If they meant 1MM cycles at an extreme load, why no mention of that? If
that was intended, it's simple in English:
"Our product will bear up to 1MM cycles of extreme load"
"Our product sustained 1MM cycles of industry standard fatigue testing"
"Our competitor's product failed at merely 985,00 cycles"

That is not what they wrote.

I was also curious about the smaller-section aero spoke showing 2.3x
longevity. That does not make any sense at all as _less_ material just
couldn't bear _2.3x_ the load cycles. And the values are nice and round,
too, 1,000,000 and 2,300,000. Convenient numbers, those, as they just
happen to fit the price curve but do they relate to the actual product?

It is not at all clear to me.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

A Muzi said:

Quoted message said:

Quoted message said:

>>> Dear Johan,
>>> Your question has come up before--it would be nice if Sapim would
>>> include a description of its testing.
>>> The Sapim spoke fatigue tests must use exaggerated stress cycles
>>> because it takes literally years to break spokes in continuous
>>> testing
>>> under ordinary low stress cycles--no spoke manufacturer sells spokes
>>> that are expected to fail in only 2,000 km of normal riding.

Quoted message said:

Quoted message said:

>> I have no doubt that it is an exaggerated test cycle. But don't they
>> know in marketing hype one doesn't cite exaggerated examples, but best
>> case scenarios. I have SAPIM-built wheels which have done closer to 40
>> 000 kms. Why would a company misrepresent itself so much? I don't
>> understand and I don't suppose there is a rational answer for this.

jim beam said:

Quoted message said:

> there /is/ a rational answer for this - almost all fatigue testing is
> done on an accelerated basis. since that's standard practice, their
> reporting is simply consistent with standard practice.-

Quoted message said:

Johan Bornman said:

You miss the point, being scientifically rational doesn't make sense
in this brochure.

jim beam said:

it makes more sense than being scientifically irrational or making
claims like "our spokes last forever if you don't use them", which is
basically where you end up if you exclude presentation of normal data.

Quoted message said:

Johan Bornman said:

It is intended for consumers who can quickly do the
sums and discover that SAPIM kind of suggests a useful life of 1 000
kms for wheels built with its spokes.

Quoted message said:

Johan Bornman said:

A good copywriter with the
company's interest at heart would have phrased the exercise completely
differently.

jim beam said:

bottom line, while /you/ may not appreciate the format, the fact is,
sapim are the only ones that dare to present fatigue data. that
should tell you more than anything else.

Maybe.
Or were those numbers pulled out of the air? "2000k lifetime" is
nonsensical to anyone with familiarity. But any ad writer would eagerly
write "one million cycles" for any product - especially if he weren't
burdened by knowledge of bikes or spokes.

no, it's standard practice engineering notation. and it's orders of
magnitude that are of interest - 1,519,341 cycles is indistinguishable
from 1,544,982 in engineering terms.

Quoted message said:

If they meant 1MM

"MM" is financial, not engineering.

Quoted message said:

cycles at an extreme load, why no mention of that? If
that was intended, it's simple in English:
"Our product will bear up to 1MM cycles of extreme load"

it's not "extreme", it's simply full cycle as opposed to indeterminate
partial cycle that you have in service. guaranteed to give shortest
life which make testing more practical too - that's why it's standard
practice.

Quoted message said:

"Our product sustained 1MM

1M, not 1MM. unless you mean $.

http://en.wikipedia.org/wiki/Engineering_notation

Quoted message said:

cycles of industry standard fatigue testing"
"Our competitor's product failed at merely 985,00 cycles"

then if they didn't name the other manufacturer, r.b.t people would
complain about lack of specificity there too! no manufacturer is
sensibly going to directly target a competitor like that unless they're
run by lawyers or like large legal expenses.

Quoted message said:

That is not what they wrote.

so they're underselling themselves! how refreshing.

Quoted message said:

I was also curious about the smaller-section aero spoke showing 2.3x
longevity. That does not make any sense at all as _less_ material just
couldn't bear _2.3x_ the load cycles.

it makes absolute sense for the reasons i've stated before. spokes fail
because of elbow bending. consider what exerts the most bending force.

Quoted message said:

And the values are nice and round,
too, 1,000,000 and 2,300,000. Convenient numbers, those, as they just
happen to fit the price curve but do they relate to the actual product?

actual product. it's standard engineering practice to use round
numbers. first, it's because these are not single spoke results, it's
for multiple samples. second, it's a log scale on the s-n graph.

Quoted message said:

It is not at all clear to me.

jim beam said:

Johan Bornman said:

In my hand I have a SAPIM brochure - Trust in SAPIM Spokes.

On the second-last page of the brochure, SAPIM has a graph showing the
estimated spoke life in wheel revolutions. The company's standard
double-butted spoke, the Race, has an estimated life of just under 1
million revolutions.

Let's say 1 million for argument sake, and that a wheel revolution
translates into two meters on the road. Therefore, the spoke life is
only 2 million meters or, 2000 kms. Not exactly something to brag
about.

that is machine testing, not wheel testing. the machine loads from
0-80kg each cycle. what does a wheel load on each cycle?

Quoted message said:

Interestingly, but as an aside to this inaccurate estimate by SAPIM,
the company's CD-Ray product, a 2,3mm wide bladed spoke, has an
estimated life of 3,5 million "Wheel Revolutions (in cycles), as SAPIM
puts it.

how much bending moment can a skinny bladed spoke exert compared to a
fat straight gauge spoke?

Except that the spoke that does second best on the test, while not
straight gauge, is a very fat spoke. The "Strong" is 2.3/2.0 and is said
to have a middle-section strength of 1400 N/mm2 and a fatigue life of
1,600,000 revolutions.

Furthermore, bending moment doesn't seem to explain why the Laser
(1.5mm center & 1,250,000 revolutions) does better than the CX (1.3mm
center along one dimension & 1,250,000 revolutions) -- unless the
bending moment is exerted by the 2.8mm dimension of the CX.

Quoted message said:

Quoted message said:

Why would the company think that it's bladed spoke will last longer
than the round one?

they don't "think", they test. if tests show one lasts longer than the
other...

Quoted message said:

Since diameter is a difficult comparison in this case, perhaps weight
is. The bladed spoke has a weight index of 278, whereas the round one
360. The index btw, is my invention, they weigh 278g per sample length
per X number of spokes.

what does weight have to do with it other than being a side-effect of
having more material?

A Muzi said:

Quoted message said:

Quoted message said:

>>> Dear Johan,
>>> Your question has come up before--it would be nice if Sapim would
>>> include a description of its testing. The Sapim spoke fatigue tests
>>> must use exaggerated stress cycles because it takes literally years
>>> to break spokes in continuous testing under ordinary low stress
>>> cycles--no spoke manufacturer sells spokes that are expected to
>>> fail in only 2,000 km of normal riding.

Quoted message said:

Quoted message said:

>> I have no doubt that it is an exaggerated test cycle. But don't they
>> know in marketing hype one doesn't cite exaggerated examples, but
>> best case scenarios. I have SAPIM-built wheels which have done
>> closer to 40 000 kms. Why would a company misrepresent itself so
>> much? I don't understand and I don't suppose there is a rational
>> answer for this.

jim beam said:

Quoted message said:

> there /is/ a rational answer for this - almost all fatigue testing is
> done on an accelerated basis. since that's standard practice, their
> reporting is simply consistent with standard practice.-

Quoted message said:

Johan Bornman said:

You miss the point, being scientifically rational doesn't make sense
in this brochure.

jim beam said:

it makes more sense than being scientifically irrational or making
claims like "our spokes last forever if you don't use them", which is
basically where you end up if you exclude presentation of normal data.

Quoted message said:

Johan Bornman said:

It is intended for consumers who can quickly do the sums and discover
that SAPIM kind of suggests a useful life of 1 000 kms for wheels
built with its spokes.

Quoted message said:

Johan Bornman said:

A good copywriter with the
company's interest at heart would have phrased the exercise completely
differently.

jim beam said:

bottom line, while /you/ may not appreciate the format, the fact is,
sapim are the only ones that dare to present fatigue data. that should
tell you more than anything else.

Maybe.
Or were those numbers pulled out of the air? "2000k lifetime" is
nonsensical to anyone with familiarity. But any ad writer would eagerly
write "one million cycles" for any product - especially if he weren't
burdened by knowledge of bikes or spokes.

If they meant 1MM cycles at an extreme load, why no mention of that? If
that was intended, it's simple in English: "Our product will bear up to
1MM cycles of extreme load" "Our product sustained 1MM cycles of
industry standard fatigue testing"
"Our competitor's product failed at merely 985,00 cycles"

That is not what they wrote.

I was also curious about the smaller-section aero spoke showing 2.3x
longevity. That does not make any sense at all as _less_ material just
couldn't bear _2.3x_ the load cycles. And the values are nice and round,
too, 1,000,000 and 2,300,000. Convenient numbers, those, as they just
happen to fit the price curve but do they relate to the actual product?

It is not at all clear to me.

Also, the Strong spoke -- a 2.3/2.0mm -- does better than all of the
thin-section spokes except the CX-Ray.

I noticed that Sapim has a new technical document on its website:

www.sapim.be/index.php?st=checklist&taal=uk

This repeats some of the oddities of the old FAQ -- e.g., throw out the
hub if a few spokes break -- and adds some new ones (CX-Ray and Race are
"more resistant to vibrations" than their other spokes?). The old FAQ is
at www.sapim.be/index.php?st=faq.

What I find interesting is that they seem to acknowledge that spoke
alignment is a problem -- see the references to a gap between spoke and
flange and between spoke and nipple (yes, they refer to a "gap" between
spoke and nipple). But instead of recommending that one correct the spoke
line, they suggest getting a new hub or using a different crossing
pattern. Since I've encountered these "gaps" even when using fairly
high-end Shimano hubs (XT and Ultegra), I'd like to know what they suggest
instead (maybe they hope that I'll buy from their marketing partner edco).