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Date: 25 Sep 2007 09:47:55
From:
Subject: Vickers numbers and chainring hardness
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I was looking at this Tour Magazine test of the Campagnolo Ultra
Torque crankset (German .pdf):
http://www.dk-content.de/tour/pdf-archiv/tests/Test_Campagnolo_Record_11-2006.pdf
They measure the stiffness of four crancksets, but also how hard the
chainrings are, as measured in Vickersnumbers, fx:
Campagnolo Record Ultra Torque: Hardness of the big chainring measured
in Vickers (HV): 203
Shimano Dura-Ace: Hardness of the big chainring measured in Vickers
(HV): 172
According to Wikipedia it looks like the measured numbers are:
"Vickers Pyramid Number (HV)"
http://en.wikipedia.org/wiki/Vickers_hardness_test
My question is if anyone knows if the Vickers number directly
correspond to wear resistance?
Eg. can one say that a chainrings higher Vickers number means longer
durability, or as in this case, that a Campagnolo Record chainring on
average should last 18 percent longer than a Dura-Ace chainring?
--
Regards
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Date: 27 Sep 2007 19:55:52
From: jim beam
Subject: Re: Vickers numbers and chainring hardness
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phs123@gmail.com wrote:
> I was looking at this Tour Magazine test of the Campagnolo Ultra
> Torque crankset (German .pdf):
> http://www.dk-content.de/tour/pdf-archiv/tests/Test_Campagnolo_Record_11-2006.pdf
>
> They measure the stiffness of four crancksets, but also how hard the
> chainrings are, as measured in Vickersnumbers, fx:
> Campagnolo Record Ultra Torque: Hardness of the big chainring measured
> in Vickers (HV): 203
> Shimano Dura-Ace: Hardness of the big chainring measured in Vickers
> (HV): 172
>
> According to Wikipedia it looks like the measured numbers are:
> "Vickers Pyramid Number (HV)"
> http://en.wikipedia.org/wiki/Vickers_hardness_test
>
> My question is if anyone knows if the Vickers number directly
> correspond to wear resistance?
> Eg. can one say that a chainrings higher Vickers number means longer
> durability, or as in this case, that a Campagnolo Record chainring on
> average should last 18 percent longer than a Dura-Ace chainring?
>
> --
> Regards
>
yes, Hv corresponds roughly to wear resistance, but in this case, you're
measuring more of the substrate than you are the surface treatment.
that's going to give very misleading numbers.
a more correct test would be microhardness or knoop testing, just like
chas says. whoever performed this testing should have raised the
suitability issue with the people saying they wanted this testing done.
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Date: 27 Sep 2007 22:42:40
From: Jim Higson
Subject: Re: Vickers numbers and chainring hardness
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phs123@gmail.com wrote:
> I was looking at this Tour Magazine test of the Campagnolo Ultra
> Torque crankset (German .pdf):
>
http://www.dk-content.de/tour/pdf-archiv/tests/Test_Campagnolo_Record_11-2006.pdf
>
> They measure the stiffness of four crancksets, but also how hard the
> chainrings are, as measured in Vickersnumbers, fx:
> Campagnolo Record Ultra Torque: Hardness of the big chainring measured
> in Vickers (HV): 203
> Shimano Dura-Ace: Hardness of the big chainring measured in Vickers
> (HV): 172
>
> According to Wikipedia it looks like the measured numbers are:
> "Vickers Pyramid Number (HV)"
> http://en.wikipedia.org/wiki/Vickers_hardness_test
>
> My question is if anyone knows if the Vickers number directly
> correspond to wear resistance?
> Eg. can one say that a chainrings higher Vickers number means longer
> durability, or as in this case, that a Campagnolo Record chainring on
> average should last 18 percent longer than a Dura-Ace chainring?
Maybe the difference would be more than that, since they are thicker (or at
least, the rear sprockets are thicker, which would suggest the chainrings
are too)
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Date: 28 Sep 2007 01:14:36
From: * * Chas
Subject: Re: Vickers numbers and chainring hardness
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"Jim Higson" <jh@333.org > wrote in message
news:pa6dneOKVLhFvmHbRVnytwA@eclipse.net.uk...
> phs123@gmail.com wrote:
>
> > I was looking at this Tour Magazine test of the Campagnolo Ultra
> > Torque crankset (German .pdf):
> >
>
http://www.dk-content.de/tour/pdf-archiv/tests/Test_Campagnolo_Record_11-2006.pdf
> >
> > They measure the stiffness of four crancksets, but also how hard the
> > chainrings are, as measured in Vickersnumbers, fx:
> > Campagnolo Record Ultra Torque: Hardness of the big chainring measured
> > in Vickers (HV): 203
> > Shimano Dura-Ace: Hardness of the big chainring measured in Vickers
> > (HV): 172
> >
> > According to Wikipedia it looks like the measured numbers are:
> > "Vickers Pyramid Number (HV)"
> > http://en.wikipedia.org/wiki/Vickers_hardness_test
> >
> > My question is if anyone knows if the Vickers number directly
> > correspond to wear resistance?
> > Eg. can one say that a chainrings higher Vickers number means longer
> > durability, or as in this case, that a Campagnolo Record chainring on
> > average should last 18 percent longer than a Dura-Ace chainring?
>
> Maybe the difference would be more than that, since they are thicker (or
at
> least, the rear sprockets are thicker, which would suggest the
chainrings
> are too)
Sprocket and chainring thickness on modern derailleur bikes is
insignificant when compared to the effects of lubrication and dirt/grit
etc.
Chas.
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Date: 25 Sep 2007 14:23:31
From:
Subject: Re: Vickers numbers and chainring hardness
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On 25 Sep., 20:22, "* * Chas" <verktygj...@aol.spamski.com > wrote:
> Those numbers are somewhat misleading. For example the thickness of the
> anodized layer or lack of it can effect the results of the hardness tests.
> The numbers are probably a better predictor of strength than wear
> resistance.
My limited understanding of work hardening of eg. cassette sprockets
is that this is of limited depth, and that when the work hardenend
layer is worn of, the exposed softer material wears so rapidly that
the usefull life of the cassette is almost over. So a measurement of
the hardness of the outer, work hardenend layer would, for all
practical purposes, be a measurement of how hard the cassette
sprockets are.
Well, I was hoping, just for once, that a simple objective measurement
could be used by consumers to compare how well at chain ring or
cassette would resist wear compared to other brands of chain rings. As
it is now, it is impossible to choose rationally between different
brands.
> Those numbers are near the bottom end of the Vickers hardness scale. The
> Brinell or Rockwell B hardness tests are probably better for soft
> materials like aluminum. Vickers is frequently used for measuring very
> hard materials.
I guess that Tour used the Vickers scale, since they also have tested
cassettes, and these seems to have Vickers numbers around 450-550
(HV),
I found another pdf files with Vickers numbers on cassettes and
chainrings from Shimano Sora to Dura-Ace, and Campagnolo Xenon to
Record. It is german, and is concerns older groups (2002):
http://www.bike-store-bergedorf.de/dokumente/vergleich_rr-gruppen.pdf
--
Regards
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Date: 25 Sep 2007 21:52:10
From: * * Chas
Subject: Re: Vickers numbers and chainring hardness
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<phs123@gmail.com > wrote in message
news:1190755411.672996.101260@n39g2000hsh.googlegroups.com...
> On 25 Sep., 20:22, "* * Chas" <verktygj...@aol.spamski.com> wrote:
>
> > Those numbers are somewhat misleading. For example the thickness of
the
> > anodized layer or lack of it can effect the results of the hardness
tests.
> > The numbers are probably a better predictor of strength than wear
> > resistance.
>
> My limited understanding of work hardening of eg. cassette sprockets
> is that this is of limited depth, and that when the work hardenend
> layer is worn of, the exposed softer material wears so rapidly that
> the usefull life of the cassette is almost over. So a measurement of
> the hardness of the outer, work hardenend layer would, for all
> practical purposes, be a measurement of how hard the cassette
> sprockets are.
> Well, I was hoping, just for once, that a simple objective measurement
> could be used by consumers to compare how well at chain ring or
> cassette would resist wear compared to other brands of chain rings. As
> it is now, it is impossible to choose rationally between different
> brands.
>
> > Those numbers are near the bottom end of the Vickers hardness scale.
The
> > Brinell or Rockwell B hardness tests are probably better for soft
> > materials like aluminum. Vickers is frequently used for measuring very
> > hard materials.
>
> I guess that Tour used the Vickers scale, since they also have tested
> cassettes, and these seems to have Vickers numbers around 450-550
> (HV),
> I found another pdf files with Vickers numbers on cassettes and
> chainrings from Shimano Sora to Dura-Ace, and Campagnolo Xenon to
> Record. It is german, and is concerns older groups (2002):
> http://www.bike-store-bergedorf.de/dokumente/vergleich_rr-gruppen.pdf
>
> --
> Regards
>
Vickers hardness is really more of a British/European measuring system. In
the US, Vickers is usually associated with very hard materials and is
compared with Knoop hardness or Rockwell A hardness.
You can't readily compare the hardness of aluminum with that of steel.
450-550 HV is the equivalent of 45-52 Rockwell C. At that hardness it's
unlikely that there would be much work hardening taking place.
The hardness of a common hand file is 60-61 Rockwell C. Work hardening
results from surface compression of the metal and varies with different
metals. Generally low carbon content steels can work harden from 46 to 50+
RC to about .005 to .020 deep. I really can't comment much without knowing
the alloy content and heat treatment of the sprockets.
Chas.
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Date: 27 Sep 2007 19:56:41
From: jim beam
Subject: Re: Vickers numbers and chainring hardness
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* * Chas wrote:
> <phs123@gmail.com> wrote in message
> news:1190755411.672996.101260@n39g2000hsh.googlegroups.com...
>> On 25 Sep., 20:22, "* * Chas" <verktygj...@aol.spamski.com> wrote:
>>
>>> Those numbers are somewhat misleading. For example the thickness of
> the
>>> anodized layer or lack of it can effect the results of the hardness
> tests.
>>> The numbers are probably a better predictor of strength than wear
>>> resistance.
>> My limited understanding of work hardening of eg. cassette sprockets
>> is that this is of limited depth, and that when the work hardenend
>> layer is worn of, the exposed softer material wears so rapidly that
>> the usefull life of the cassette is almost over. So a measurement of
>> the hardness of the outer, work hardenend layer would, for all
>> practical purposes, be a measurement of how hard the cassette
>> sprockets are.
>> Well, I was hoping, just for once, that a simple objective measurement
>> could be used by consumers to compare how well at chain ring or
>> cassette would resist wear compared to other brands of chain rings. As
>> it is now, it is impossible to choose rationally between different
>> brands.
>>
>>> Those numbers are near the bottom end of the Vickers hardness scale.
> The
>>> Brinell or Rockwell B hardness tests are probably better for soft
>>> materials like aluminum. Vickers is frequently used for measuring very
>>> hard materials.
>> I guess that Tour used the Vickers scale, since they also have tested
>> cassettes, and these seems to have Vickers numbers around 450-550
>> (HV),
>> I found another pdf files with Vickers numbers on cassettes and
>> chainrings from Shimano Sora to Dura-Ace, and Campagnolo Xenon to
>> Record. It is german, and is concerns older groups (2002):
>> http://www.bike-store-bergedorf.de/dokumente/vergleich_rr-gruppen.pdf
>>
>> --
>> Regards
>>
>
> Vickers hardness is really more of a British/European measuring system. In
> the US, Vickers is usually associated with very hard materials and is
> compared with Knoop hardness or Rockwell A hardness.
indeed.
>
> You can't readily compare the hardness of aluminum with that of steel.
> 450-550 HV is the equivalent of 45-52 Rockwell C. At that hardness it's
> unlikely that there would be much work hardening taking place.
>
> The hardness of a common hand file is 60-61 Rockwell C. Work hardening
> results from surface compression of the metal
not the correct explanation, although it may appear that way. actual
reason for increase in hardness is increasing dislocation density, and
that's simply a matter of deformation, not compression as such.
> and varies with different
> metals.
indeed.
> Generally low carbon content steels can work harden from 46 to 50+
> RC to about .005 to .020 deep.
they can harden like you say, but it's not just a surface depth thing.
if the whole body is deformed, the whole body work hardens.
> I really can't comment much without knowing
> the alloy content and heat treatment of the sprockets.
>
> Chas.
>
>
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Date: 25 Sep 2007 16:22:11
From: A Muzi
Subject: Re: Vickers numbers and chainring hardness
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phs123@gmail.com wrote:
> I was looking at this Tour Magazine test of the Campagnolo Ultra
> Torque crankset (German .pdf):
> http://www.dk-content.de/tour/pdf-archiv/tests/Test_Campagnolo_Record_11-2006.pdf
>
> They measure the stiffness of four crancksets, but also how hard the
> chainrings are, as measured in Vickersnumbers, fx:
> Campagnolo Record Ultra Torque: Hardness of the big chainring measured
> in Vickers (HV): 203
> Shimano Dura-Ace: Hardness of the big chainring measured in Vickers
> (HV): 172
>
> According to Wikipedia it looks like the measured numbers are:
> "Vickers Pyramid Number (HV)"
> http://en.wikipedia.org/wiki/Vickers_hardness_test
>
> My question is if anyone knows if the Vickers number directly
> correspond to wear resistance?
> Eg. can one say that a chainrings higher Vickers number means longer
> durability, or as in this case, that a Campagnolo Record chainring on
> average should last 18 percent longer than a Dura-Ace chainring?
Campagnolo rings do wear quite well. But for a direct % comparison you'd
have to say "all else being equal" and jammed chain on missed shifts,
worn chain, crud, abuse, etc may vary.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
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Date: 25 Sep 2007 11:22:02
From: * * Chas
Subject: Re: Vickers numbers and chainring hardness
|
<phs123@gmail.com > wrote in message
news:1190738875.579770.206860@n39g2000hsh.googlegroups.com...
> I was looking at this Tour Magazine test of the Campagnolo Ultra
> Torque crankset (German .pdf):
>
http://www.dk-content.de/tour/pdf-archiv/tests/Test_Campagnolo_Record_11-2006.pdf
>
> They measure the stiffness of four crancksets, but also how hard the
> chainrings are, as measured in Vickersnumbers, fx:
> Campagnolo Record Ultra Torque: Hardness of the big chainring measured
> in Vickers (HV): 203
> Shimano Dura-Ace: Hardness of the big chainring measured in Vickers
> (HV): 172
>
> According to Wikipedia it looks like the measured numbers are:
> "Vickers Pyramid Number (HV)"
> http://en.wikipedia.org/wiki/Vickers_hardness_test
>
> My question is if anyone knows if the Vickers number directly
> correspond to wear resistance?
> Eg. can one say that a chainrings higher Vickers number means longer
> durability, or as in this case, that a Campagnolo Record chainring on
> average should last 18 percent longer than a Dura-Ace chainring?
>
> --
> Regards
>
Those numbers are somewhat misleading. For example the thickness of the
anodized layer or lack of it can effect the results of the hardness tests.
The numbers are probably a better predictor of strength than wear
resistance.
Those numbers are near the bottom end of the Vickers hardness scale. The
Brinell or Rockwell B hardness tests are probably better for soft
materials like aluminum. Vickers is frequently used for measuring very
hard materials.
Here's a site with an interactive hardness converter:
http://www.efunda.com/units/hardness/convert_hardness.cfm?HD=HV&Cat=Steel#ConvInto
Chas.
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