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Main
Date: 14 Sep 2007 01:35:57
From:
Subject: Cracks and spoke tension
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I just noticed cracks around ALL right hand eylets on my Mavic Reflex
tubular rim (32 hole, grey non-anodised). The cracks look similar to
these: http://web.onetel.net.uk/~davidwgreen/rimpics/4.JPG but some of
them are from side to side and at least one was all the way to the
"corner" where the side begins.
The rim is just a couple of years old and hasn't been ridden more than
5000 km. I build it myself using old spokes (DT 2/1.8 mm) and rather
high tension (the old rim had ~1300 N, this is probably about the
same, not yet on the "taco" limit) for right hand side. I weigh 82 kg
and ride on quite smooth roads.
The old rim was an anodised GP4, which I rode about 20 000 km until
one eylet was pulled through the rim. I hoped, that this new rim would
be better....
Am I just unlucky, is this a poor rim type or is the tension I use too
much? With lower tension I have had lot of problems with self
loosening left side spokes, which required wrenching every 100-200 km.
This wheel has stayed true.
If this rim fails, which low profile low cost tubular rim would you
recommend?
Joakim
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Date: 22 Sep 2007 07:10:09
From:
Subject: Re: Cracks and spoke tension
|
I just measured that the spoke tension was on DS very constantly 1400
N and on NDS it varied +-10% around 700 N.
joakim
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Date: 22 Sep 2007 16:49:30
From: Antti Salonen
Subject: Re: Cracks and spoke tension
|
joakim.majander@luukku.com wrote:
> I just measured that the spoke tension was on DS very constantly 1400
> N and on NDS it varied +-10% around 700 N.
1400 N sounds high for a rim like Reflex. I wouldn't go beyond about 100
kg, and if it's not enough to keep the wheel true for the rider, some or
all of the parts need to change.
If you rebuild the wheel with a lower tension, do something about the
NDS spokes if you've had problem with them before. Use the thinnest
spoke on the market (DT Revolution or Sapim Laser), because they don't
lose their tension under load as easily. Also, don't lubricate the NDS
spoke threads more than necessary when you build the wheel, or even use
some kind of thread lock.
Antti
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Date: 22 Sep 2007 07:37:29
From: jim beam
Subject: Re: Cracks and spoke tension
|
joakim.majander@luukku.com wrote:
> I just measured that the spoke tension was on DS very constantly 1400
> N and on NDS it varied +-10% around 700 N.
>
> joakim
>
well, that's the problem causing the rim cracking - drive side tension
is too high. simply re-build with a new rim and correct spoke tension,
then you'll be fine.
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Date: 16 Sep 2007 12:52:10
From:
Subject: Re: Cracks and spoke tension
|
On Sep 16, 9:37 am, jim beam <spamvor...@bad.example.net > wrote:
> frkry...@gmail.com wrote:
> > On Sep 15, 6:45 pm, spikenett...@earthlink.net wrote:
>
> >> Thank you for your reply, but I what I said in my post stands as
> >> correct. Clearly the mass per unit length of the vibrating spoke, 'm'
> >> in the formula, depends on its cross-sectional area - its thickness.
> >> This is how spoke gauge enters into the formula, and from the formula
> >> the spokes frequency of vibration is seen to be inversely proportional
> >> to its thickness.
>
> >> Please consider the following three cases, all derived directly from
> >> the formula:
>
> >> 1 -Two spokes of the same length, pitch, and gauge have the same
> >> tension. This is the trivial case.
>
> >> 2 -Two spokes of the same length, pitch, but of different gauge have
> >> the same tension per unit cross-sectional area.
>
> >> 3 -Two spokes of the same length, pitch, but of different gauge have
> >> different tensions. The thicker spoke has a higher tension.
>
> >> The author somehow, despite his credentials, has confused 2 and 3
> >> above; he collapses, as I said before, the distinction between spoke
> >> tension per unit cross-sectional area and spoke tension. In his
> >> muddled article he infers that the same pitch indicates the same spoke
> >> tension without consideration of whether the two spokes are the same
> >> gauge. I am aware of his credentials to the extent that they are
> >> indicated on the linked site. That is why I gratuitously said maybe it
> >> was I who was confused.
>
> >> With all due respect, when the outcome of a calculation or analysis
> >> seems to go against common sense and experience, one should reexamine
> >> the calculation or analysis very carefully - unless you want to be
> >> just like jim.
>
> > Hmm. You're right! I guess I made the same mistake John Allen did,
> > which is exactly what you warned about. Sadly, I still didn't catch
> > it.
>
> > Another (non-mathematical) way of explaining the mistake is this: In
> > step two of his three-part scenario, he neglects that the _total_
> > tension in the two "lightly connected" spokes is actually twice as
> > great. And therefore, merging them into one spoke of double area
> > requires twice the individual tension to vibrate at the same
> > frequency.
>
> > OK, I stand corrected. Now we've got to get John Allen to make a
> > correction.
>
> > - Frank Krygowski
>
> [watching this thread with interest...]
>
> you've just earned a shopping cart-sized "no abuse" credit.
>
> mistakes are fine - just fix them and move on.
>
> for the benefit of certain others however, entrenched refusal to do so,
> particularly when repeated in a public forum, and /especially/ when used
> as a basis for criticism [!!!], is simply pissing in the knowledge pool
> - about as antisocial as it gets.
beam writes:
< mistakes are fine - just fix them and move on.
Good advice. Seems to me that this is something you have needed to do
countless times but have not done. But, of course, you do move on,
acting as if nothing has happened.
No class -- zero credibility.
--
Spike
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Date: 16 Sep 2007 13:28:53
From: jim beam
Subject: Re: Cracks and spoke tension
|
spikenettles@earthlink.net wrote:
> On Sep 16, 9:37 am, jim beam <spamvor...@bad.example.net> wrote:
>> frkry...@gmail.com wrote:
>>> On Sep 15, 6:45 pm, spikenett...@earthlink.net wrote:
>>>> Thank you for your reply, but I what I said in my post stands as
>>>> correct. Clearly the mass per unit length of the vibrating spoke, 'm'
>>>> in the formula, depends on its cross-sectional area - its thickness.
>>>> This is how spoke gauge enters into the formula, and from the formula
>>>> the spokes frequency of vibration is seen to be inversely proportional
>>>> to its thickness.
>>>> Please consider the following three cases, all derived directly from
>>>> the formula:
>>>> 1 -Two spokes of the same length, pitch, and gauge have the same
>>>> tension. This is the trivial case.
>>>> 2 -Two spokes of the same length, pitch, but of different gauge have
>>>> the same tension per unit cross-sectional area.
>>>> 3 -Two spokes of the same length, pitch, but of different gauge have
>>>> different tensions. The thicker spoke has a higher tension.
>>>> The author somehow, despite his credentials, has confused 2 and 3
>>>> above; he collapses, as I said before, the distinction between spoke
>>>> tension per unit cross-sectional area and spoke tension. In his
>>>> muddled article he infers that the same pitch indicates the same spoke
>>>> tension without consideration of whether the two spokes are the same
>>>> gauge. I am aware of his credentials to the extent that they are
>>>> indicated on the linked site. That is why I gratuitously said maybe it
>>>> was I who was confused.
>>>> With all due respect, when the outcome of a calculation or analysis
>>>> seems to go against common sense and experience, one should reexamine
>>>> the calculation or analysis very carefully - unless you want to be
>>>> just like jim.
>>> Hmm. You're right! I guess I made the same mistake John Allen did,
>>> which is exactly what you warned about. Sadly, I still didn't catch
>>> it.
>>> Another (non-mathematical) way of explaining the mistake is this: In
>>> step two of his three-part scenario, he neglects that the _total_
>>> tension in the two "lightly connected" spokes is actually twice as
>>> great. And therefore, merging them into one spoke of double area
>>> requires twice the individual tension to vibrate at the same
>>> frequency.
>>> OK, I stand corrected. Now we've got to get John Allen to make a
>>> correction.
>>> - Frank Krygowski
>> [watching this thread with interest...]
>>
>> you've just earned a shopping cart-sized "no abuse" credit.
>>
>> mistakes are fine - just fix them and move on.
>>
>> for the benefit of certain others however, entrenched refusal to do so,
>> particularly when repeated in a public forum, and /especially/ when used
>> as a basis for criticism [!!!], is simply pissing in the knowledge pool
>> - about as antisocial as it gets.
>
> beam writes:
>
> < mistakes are fine - just fix them and move on.
>
> Good advice. Seems to me that this is something you have needed to do
> countless times but have not done. But, of course, you do move on,
> acting as if nothing has happened.
>
> No class -- zero credibility.
> --
> Spike
>
don't just do a drive-by shooting without cause - go ahead and point out
what you think is a problem!
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Date: 15 Sep 2007 19:57:30
From:
Subject: Re: Cracks and spoke tension
|
On Sep 15, 9:07 pm, frkry...@gmail.com wrote:
snip
> OK, I stand corrected.
snip
Frank,
Wow. All class -- 100% credibility.
Spike
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Date: 16 Sep 2007 02:07:55
From:
Subject: Re: Cracks and spoke tension
|
On Sep 15, 6:45 pm, spikenett...@earthlink.net wrote:
>
>
> Thank you for your reply, but I what I said in my post stands as
> correct. Clearly the mass per unit length of the vibrating spoke, 'm'
> in the formula, depends on its cross-sectional area - its thickness.
> This is how spoke gauge enters into the formula, and from the formula
> the spokes frequency of vibration is seen to be inversely proportional
> to its thickness.
>
> Please consider the following three cases, all derived directly from
> the formula:
>
> 1 -Two spokes of the same length, pitch, and gauge have the same
> tension. This is the trivial case.
>
> 2 -Two spokes of the same length, pitch, but of different gauge have
> the same tension per unit cross-sectional area.
>
> 3 -Two spokes of the same length, pitch, but of different gauge have
> different tensions. The thicker spoke has a higher tension.
>
> The author somehow, despite his credentials, has confused 2 and 3
> above; he collapses, as I said before, the distinction between spoke
> tension per unit cross-sectional area and spoke tension. In his
> muddled article he infers that the same pitch indicates the same spoke
> tension without consideration of whether the two spokes are the same
> gauge. I am aware of his credentials to the extent that they are
> indicated on the linked site. That is why I gratuitously said maybe it
> was I who was confused.
>
> With all due respect, when the outcome of a calculation or analysis
> seems to go against common sense and experience, one should reexamine
> the calculation or analysis very carefully - unless you want to be
> just like jim.
Hmm. You're right! I guess I made the same mistake John Allen did,
which is exactly what you warned about. Sadly, I still didn't catch
it.
Another (non-mathematical) way of explaining the mistake is this: In
step two of his three-part scenario, he neglects that the _total_
tension in the two "lightly connected" spokes is actually twice as
great. And therefore, merging them into one spoke of double area
requires twice the individual tension to vibrate at the same
frequency.
OK, I stand corrected. Now we've got to get John Allen to make a
correction.
- Frank Krygowski
|
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Date: 16 Sep 2007 07:37:42
From: jim beam
Subject: Re: Cracks and spoke tension
|
frkrygow@gmail.com wrote:
> On Sep 15, 6:45 pm, spikenett...@earthlink.net wrote:
>>
>> Thank you for your reply, but I what I said in my post stands as
>> correct. Clearly the mass per unit length of the vibrating spoke, 'm'
>> in the formula, depends on its cross-sectional area - its thickness.
>> This is how spoke gauge enters into the formula, and from the formula
>> the spokes frequency of vibration is seen to be inversely proportional
>> to its thickness.
>>
>> Please consider the following three cases, all derived directly from
>> the formula:
>>
>> 1 -Two spokes of the same length, pitch, and gauge have the same
>> tension. This is the trivial case.
>>
>> 2 -Two spokes of the same length, pitch, but of different gauge have
>> the same tension per unit cross-sectional area.
>>
>> 3 -Two spokes of the same length, pitch, but of different gauge have
>> different tensions. The thicker spoke has a higher tension.
>>
>> The author somehow, despite his credentials, has confused 2 and 3
>> above; he collapses, as I said before, the distinction between spoke
>> tension per unit cross-sectional area and spoke tension. In his
>> muddled article he infers that the same pitch indicates the same spoke
>> tension without consideration of whether the two spokes are the same
>> gauge. I am aware of his credentials to the extent that they are
>> indicated on the linked site. That is why I gratuitously said maybe it
>> was I who was confused.
>>
>> With all due respect, when the outcome of a calculation or analysis
>> seems to go against common sense and experience, one should reexamine
>> the calculation or analysis very carefully - unless you want to be
>> just like jim.
>
> Hmm. You're right! I guess I made the same mistake John Allen did,
> which is exactly what you warned about. Sadly, I still didn't catch
> it.
>
> Another (non-mathematical) way of explaining the mistake is this: In
> step two of his three-part scenario, he neglects that the _total_
> tension in the two "lightly connected" spokes is actually twice as
> great. And therefore, merging them into one spoke of double area
> requires twice the individual tension to vibrate at the same
> frequency.
>
> OK, I stand corrected. Now we've got to get John Allen to make a
> correction.
>
> - Frank Krygowski
>
[watching this thread with interest...]
you've just earned a shopping cart-sized "no abuse" credit.
mistakes are fine - just fix them and move on.
for the benefit of certain others however, entrenched refusal to do so,
particularly when repeated in a public forum, and /especially/ when used
as a basis for criticism [!!!], is simply pissing in the knowledge pool
- about as antisocial as it gets.
|
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Date: 15 Sep 2007 23:42:57
From: Chalo
Subject: Re: Cracks and spoke tension
|
jim beam wrote:
>
> Chalo wrote:
> >
> > Most of Mavic's rims use 6106 aluminum-- just about the weakest of the
> > 6000 series--
>
> any idea what their "maxtal" alloy is?
"20% stronger!" or some such business. Meaning "about as strong as
the 6061 alloy in Alex rims that cost 1/4 as much". Only a couple of
Mavic rims are made with Maxtal alloy, whatever that is. The rest are
6106, including the A719 which turned out to be the most disappointing
rim I ever wasted money on.
http://www.google.com/search?hl=en&q=mavic+6106
> > in order to get a sharp looking finish on the
> > extrusion.
>
> that bit can't be true - they anodize it and that covers a multitude of
> sins.
Well, that's what 6106 alloy is for, and why folks (including
Velocity) use it despite the fact that it's much weaker than other
aluminum alloys commonly used in bikes. Mavic and Velocity extrusions
do look nicer-- crisper and smoother-- than Alex extrusions with
similar finishes. There's a cost, though. Velocity mitigates the
shortcomings of soft alloy by using structurally optimized shapes.
Mavic seems to deal with it by overhardening their extrusions (which
causes other problems in turn).
> > Thus they get spoke
> > holes that crack and sidewalls from which segments break off. I have
> > seen these things happen much more often with Adidas-Salomon-Mavic
> > rims than with all other rims combined.
>
> and most other rims weigh more. what about d.t. rims - they're
> weight/feature/performance competitive. have you tried those?
DT doesn't make any sturdy rims. They are also very poor value
compared to Alex and Sun.
> > Paradoxically, they seem to do this aggressive heat treatment _before_
> > welding, which means they get the worst of both the soft material in
> > the weld and the brittle material elsewhere in the rim.
>
> why not declare this a "bash mavic" weekend and be done with it?
I just call them like I see them. I wanted to like Mavic-- they made
my favorite rims in the '80s and early '90s when other decent choices
were slim. Not just the MA2 and MA40, but the Open 4, Module 3,
Module 4, and Oxygen M6 were excellent rims in most respects,
beautiful and reliable for their weights. But then the M261 showed up
with its achy breaky sidewalls, and things just deteriorated from
there. The decline of Mavic was correlated with the takeover of the
company by Salomon, but I didn't learn that until years after I'd
noticed the symptoms.
Chalo
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Date: 15 Sep 2007 15:45:38
From:
Subject: Re: Cracks and spoke tension
|
On Sep 15, 10:46 am, frkry...@gmail.com wrote:
> On Sep 15, 1:15 am, spikenett...@earthlink.net wrote:
>
>
>
> > On Sep 14, 9:15 am, joakim.majan...@luukku.com wrote:
> > Some background: http://www.bikexprt.com/bicycle/pitcheqn.htm
>
> > Good that you obtained your own values. I looked at the above linked
> > article on spoke tension determination by musical pitch: Why Correct
> > Musical Pitch Depends On Spoke Length And Not On Thickness. Although
> > I am not an engineer, physicist, mathematician, musician, etc, it is
> > clear to me that the author, in his initial exposition, unwittingly
> > collapsed the distinction between a spoke's tension and a spoke's
> > tension per its unit cross-sectional area. The result is his implied
> > counter intuitive and erroneous conclusion that two spokes of the same
> > length and pitch have the same tension regardless of their thickness -
> > regardless of their gauge.
>
> > If the author used say 16 gauge spokes to develop his table of
> > pitches, then someone building a wheel using 14 gauge spokes and these
> > musical pitches should also be prepared for the percussion of popping
> > eyelets. Still, I'm a little confused here; the author's credentials
> > seems to indicate that he is not just another "ex-metallurgist".
>
> I think you are, indeed, confused here. John Allen explains exactly
> what you're worried about in the paragraph under the equation - the
> one that ends "It still vibrates at the same frequency."
>
> You can find the equation he quotes in many physics books. As a
> double check, you can review the units of measurement on the equation
> to indicate that it is valid as it stands. The spoke gage (or cross
> sectional area) does not appear in the equation, indicating it does
> not make a difference, even if that seems counterintuitive.
>
> BTW, John Allen is an engineer and a musician. (I am too.) He knows
> what he's writing about.
>
> - Frank Krygowski
Thank you for your reply, but I what I said in my post stands as
correct. Clearly the mass per unit length of the vibrating spoke, 'm'
in the formula, depends on its cross-sectional area - its thickness.
This is how spoke gauge enters into the formula, and from the formula
the spokes frequency of vibration is seen to be inversely proportional
to its thickness.
Please consider the following three cases, all derived directly from
the formula:
1 -Two spokes of the same length, pitch, and gauge have the same
tension. This is the trivial case.
2 -Two spokes of the same length, pitch, but of different gauge have
the same tension per unit cross-sectional area.
3 -Two spokes of the same length, pitch, but of different gauge have
different tensions. The thicker spoke has a higher tension.
The author somehow, despite his credentials, has confused 2 and 3
above; he collapses, as I said before, the distinction between spoke
tension per unit cross-sectional area and spoke tension. In his
muddled article he infers that the same pitch indicates the same spoke
tension without consideration of whether the two spokes are the same
gauge. I am aware of his credentials to the extent that they are
indicated on the linked site. That is why I gratuitously said maybe it
was I who was confused.
With all due respect, when the outcome of a calculation or analysis
seems to go against common sense and experience, one should reexamine
the calculation or analysis very carefully - unless you want to be
just like jim.
--
Spike
|
| | |
Date: 15 Sep 2007 20:22:20
From:
Subject: Re: Cracks and spoke tension
|
On Sat, 15 Sep 2007 15:45:38 -0700, spikenettles@earthlink.net wrote:
>On Sep 15, 10:46 am, frkry...@gmail.com wrote:
>> On Sep 15, 1:15 am, spikenett...@earthlink.net wrote:
>>
>>
>>
>> > On Sep 14, 9:15 am, joakim.majan...@luukku.com wrote:
>> > Some background: http://www.bikexprt.com/bicycle/pitcheqn.htm
>>
>> > Good that you obtained your own values. I looked at the above linked
>> > article on spoke tension determination by musical pitch: Why Correct
>> > Musical Pitch Depends On Spoke Length And Not On Thickness. Although
>> > I am not an engineer, physicist, mathematician, musician, etc, it is
>> > clear to me that the author, in his initial exposition, unwittingly
>> > collapsed the distinction between a spoke's tension and a spoke's
>> > tension per its unit cross-sectional area. The result is his implied
>> > counter intuitive and erroneous conclusion that two spokes of the same
>> > length and pitch have the same tension regardless of their thickness -
>> > regardless of their gauge.
>>
>> > If the author used say 16 gauge spokes to develop his table of
>> > pitches, then someone building a wheel using 14 gauge spokes and these
>> > musical pitches should also be prepared for the percussion of popping
>> > eyelets. Still, I'm a little confused here; the author's credentials
>> > seems to indicate that he is not just another "ex-metallurgist".
>>
>> I think you are, indeed, confused here. John Allen explains exactly
>> what you're worried about in the paragraph under the equation - the
>> one that ends "It still vibrates at the same frequency."
>>
>> You can find the equation he quotes in many physics books. As a
>> double check, you can review the units of measurement on the equation
>> to indicate that it is valid as it stands. The spoke gage (or cross
>> sectional area) does not appear in the equation, indicating it does
>> not make a difference, even if that seems counterintuitive.
>>
>> BTW, John Allen is an engineer and a musician. (I am too.) He knows
>> what he's writing about.
>>
>> - Frank Krygowski
>
>Thank you for your reply, but I what I said in my post stands as
>correct. Clearly the mass per unit length of the vibrating spoke, 'm'
>in the formula, depends on its cross-sectional area - its thickness.
>This is how spoke gauge enters into the formula, and from the formula
>the spokes frequency of vibration is seen to be inversely proportional
>to its thickness.
>
>Please consider the following three cases, all derived directly from
>the formula:
>
>1 -Two spokes of the same length, pitch, and gauge have the same
>tension. This is the trivial case.
>
>2 -Two spokes of the same length, pitch, but of different gauge have
>the same tension per unit cross-sectional area.
>
>3 -Two spokes of the same length, pitch, but of different gauge have
>different tensions. The thicker spoke has a higher tension.
>
>The author somehow, despite his credentials, has confused 2 and 3
>above; he collapses, as I said before, the distinction between spoke
>tension per unit cross-sectional area and spoke tension. In his
>muddled article he infers that the same pitch indicates the same spoke
>tension without consideration of whether the two spokes are the same
>gauge. I am aware of his credentials to the extent that they are
>indicated on the linked site. That is why I gratuitously said maybe it
>was I who was confused.
>
>With all due respect, when the outcome of a calculation or analysis
>seems to go against common sense and experience, one should reexamine
>the calculation or analysis very carefully - unless you want to be
>just like jim.
Dear Spike,
That's pretty much how I understood thickness and mass would affect
tone.
The high-pitched E string on the violin is much thinner than the
low-pitched G string. Length is exactly the same.
"The heavier the gauge, the thicker the string, and the greater the
tension required to bring the string up to the desired pitch."
http://www.tmfiddle.com/Violin_Music/Buy/Strings/Stringbuyersguide.aspx
On the piano, the thin, short strings are the high notes, and the much
longer and thicker strings are the low notes. The same thing is even
more obvious with a harp.
A curious detail that escaped me is that that violin strings of the
same length, tension, and thickness produce a lower note when made of
metal (denser, more mass) than gut:
http://books.google.com/books?id=sAzLw8_izhEC&pg=RA1-PA236&lpg=RA1-PA236&dq=violin+string+tension+tone+thickness&source=web&ots=SoVpQMSg1-&sig=woOCroE9hG3CaQQLiOZJZ7Av-iA
Cheers,
Carl Fogel
|
| |
Date: 15 Sep 2007 15:46:48
From:
Subject: Re: Cracks and spoke tension
|
On Sep 15, 1:15 am, spikenett...@earthlink.net wrote:
> On Sep 14, 9:15 am, joakim.majan...@luukku.com wrote:
> Some background: http://www.bikexprt.com/bicycle/pitcheqn.htm
>
>
> Good that you obtained your own values. I looked at the above linked
> article on spoke tension determination by musical pitch: Why Correct
> Musical Pitch Depends On Spoke Length And Not On Thickness. Although
> I am not an engineer, physicist, mathematician, musician, etc, it is
> clear to me that the author, in his initial exposition, unwittingly
> collapsed the distinction between a spoke's tension and a spoke's
> tension per its unit cross-sectional area. The result is his implied
> counter intuitive and erroneous conclusion that two spokes of the same
> length and pitch have the same tension regardless of their thickness -
> regardless of their gauge.
>
> If the author used say 16 gauge spokes to develop his table of
> pitches, then someone building a wheel using 14 gauge spokes and these
> musical pitches should also be prepared for the percussion of popping
> eyelets. Still, I'm a little confused here; the author's credentials
> seems to indicate that he is not just another "ex-metallurgist".
I think you are, indeed, confused here. John Allen explains exactly
what you're worried about in the paragraph under the equation - the
one that ends "It still vibrates at the same frequency."
You can find the equation he quotes in many physics books. As a
double check, you can review the units of measurement on the equation
to indicate that it is valid as it stands. The spoke gage (or cross
sectional area) does not appear in the equation, indicating it does
not make a difference, even if that seems counterintuitive.
BTW, John Allen is an engineer and a musician. (I am too.) He knows
what he's writing about.
- Frank Krygowski
|
| |
Date: 14 Sep 2007 22:15:54
From:
Subject: Re: Cracks and spoke tension
|
On Sep 14, 9:15 am, joakim.majan...@luukku.com wrote:
snip
> I have measured the tensions from the previous rim using a sound
> analyser (well actually only a program on laptop), which can detect
> the harmonic frequencies. Then you need to know the free length and
> the specific weight of the spoke in order to calculate the tension.
> You can actually find two or three different frequencies for each
> spoke (from rim to hub, from rim to first crossing etc.). Some
> background:http://www.bikexprt.com/bicycle/pitcheqn.htm
snip
> Joakim
Good that you obtained your own values. I looked at the above linked
article on spoke tension determination by musical pitch: Why Correct
Musical Pitch Depends On Spoke Length And Not On Thickness. Although
I am not an engineer, physicist, mathematician, musician, etc, it is
clear to me that the author, in his initial exposition, unwittingly
collapsed the distinction between a spoke's tension and a spoke's
tension per its unit cross-sectional area. The result is his implied
counter intuitive and erroneous conclusion that two spokes of the same
length and pitch have the same tension regardless of their thickness -
regardless of their gauge.
If the author used say 16 gauge spokes to develop his table of
pitches, then someone building a wheel using 14 gauge spokes and these
musical pitches should also be prepared for the percussion of popping
eyelets. Still, I'm a little confused here; the author's credentials
seems to indicate that he is not just another "ex-metallurgist".
--
Spike
|
| |
Date: 15 Sep 2007 05:07:04
From: Chalo
Subject: Re: Cracks and spoke tension
|
jim beam wrote:
>
> Chalo wrote:
> >
> > jim beam wrote:
> >>
> >> and what is /your/ spoke tension???
> >
> > I'll venture a guess: too high for Mavic's overcooked crappy alloy!
> > (But probably not too high for a better-made rim.)
>
> the only mavic rim i've ever succeeded in cracking is one with spoke
> tension > 175N [off the end of the scale for my park tensiometer]. it's
> a single eyelet x517 and i weigh #205+. perversely, i don't consider
> this the result of "overcooked crappy alloy".
Do you mean 175kgf?
Most of Mavic's rims use 6106 aluminum-- just about the weakest of the
6000 series-- in order to get a sharp looking finish on the
extrusion. For using some of the softest structural alloy money can
buy, their rims sure don't seem very ductile. I believe they do some
monkey business with heat treatment in an attempt to buy back the
hardness sacrificed in using a weak, soft alloy. Thus they get spoke
holes that crack and sidewalls from which segments break off. I have
seen these things happen much more often with Adidas-Salomon-Mavic
rims than with all other rims combined.
Paradoxically, they seem to do this aggressive heat treatment _before_
welding, which means they get the worst of both the soft material in
the weld and the brittle material elsewhere in the rim.
Chalo
|
| | |
Date: 15 Sep 2007 06:21:48
From: jim beam
Subject: Re: Cracks and spoke tension
|
Chalo wrote:
> jim beam wrote:
>> Chalo wrote:
>>> jim beam wrote:
>>>> and what is /your/ spoke tension???
>>> I'll venture a guess: too high for Mavic's overcooked crappy alloy!
>>> (But probably not too high for a better-made rim.)
>> the only mavic rim i've ever succeeded in cracking is one with spoke
>> tension > 175N [off the end of the scale for my park tensiometer]. it's
>> a single eyelet x517 and i weigh #205+. perversely, i don't consider
>> this the result of "overcooked crappy alloy".
>
> Do you mean 175kgf?
yes!
>
> Most of Mavic's rims use 6106 aluminum-- just about the weakest of the
> 6000 series--
any idea what their "maxtal" alloy is?
> in order to get a sharp looking finish on the
> extrusion.
that bit can't be true - they anodize it and that covers a multitude of
sins.
> For using some of the softest structural alloy money can
> buy, their rims sure don't seem very ductile. I believe they do some
> monkey business with heat treatment in an attempt to buy back the
> hardness sacrificed in using a weak, soft alloy. Thus they get spoke
> holes that crack and sidewalls from which segments break off. I have
> seen these things happen much more often with Adidas-Salomon-Mavic
> rims than with all other rims combined.
and most other rims weigh more. what about d.t. rims - they're
weight/feature/performance competitive. have you tried those?
>
> Paradoxically, they seem to do this aggressive heat treatment _before_
> welding, which means they get the worst of both the soft material in
> the weld and the brittle material elsewhere in the rim.
why not declare this a "bash mavic" weekend and be done with it?
|
| | | |
Date: 15 Sep 2007 22:22:33
From: Antti Salonen
Subject: Re: Cracks and spoke tension
|
jim beam <spamvortex@bad.example.net > wrote:
> and most other rims weigh more. what about d.t. rims - they're
> weight/feature/performance competitive. have you tried those?
I tried the DT RR 1.1 and wasn't impressed. I built the rear with
about 100 to 110 kg tension on the drive-side, and it started showing
cracks around the drive-side eyelets. Front wheel lasted fine but I
tensioned the spokes only to about 90 kg. I did put almost 15 thousand
km on the wheels, but they were carefully built and I'm only about 60
kg, so I was definitely expecting more.
Not surprisingly, DT started selling a double-eyelet version of the same
rim, but it's of course significantly heavier and in my view not
competetive either. As far as I can tell, probably the best lightweight
road rim on the market is Velocity Aerohead, but Velocity doesn't seem
able to bring their product to the European market.
Actually I'm starting to feel that given the poor quality of road rims
on the market, if you want to get a pair of reasonably light, aero and
durable wheels, boutique wheels might actually be the way to go. For
about 350 euro you can get a pair of Campagnolo (or Fulcrum) wheels with
Record class hubs and rims that seem to last fine. If you're unlucky
you might bust the rim, but other than that serviceability is not a
problem. Replacement spokes are a bit expensive, but 20 euro for the
spoke kit doesn't really change the equation.
Antti
|
| | | | |
Date: 16 Sep 2007 14:08:52
From: A Muzi
Subject: Re: Cracks and spoke tension
|
> jim beam <spamvortex@bad.example.net> wrote:
>> and most other rims weigh more. what about d.t. rims - they're
>> weight/feature/performance competitive. have you tried those?
Antti Salonen wrote:
> I tried the DT RR 1.1 and wasn't impressed. I built the rear with
> about 100 to 110 kg tension on the drive-side, and it started showing
> cracks around the drive-side eyelets. Front wheel lasted fine but I
> tensioned the spokes only to about 90 kg. I did put almost 15 thousand
> km on the wheels, but they were carefully built and I'm only about 60
> kg, so I was definitely expecting more.
>
> Not surprisingly, DT started selling a double-eyelet version of the same
> rim, but it's of course significantly heavier and in my view not
> competetive either. As far as I can tell, probably the best lightweight
> road rim on the market is Velocity Aerohead, but Velocity doesn't seem
> able to bring their product to the European market.
>
> Actually I'm starting to feel that given the poor quality of road rims
> on the market, if you want to get a pair of reasonably light, aero and
> durable wheels, boutique wheels might actually be the way to go. For
> about 350 euro you can get a pair of Campagnolo (or Fulcrum) wheels with
> Record class hubs and rims that seem to last fine. If you're unlucky
> you might bust the rim, but other than that serviceability is not a
> problem. Replacement spokes are a bit expensive, but 20 euro for the
> spoke kit doesn't really change the equation.
We and others commonly ship to UK and EU, both rims and wheels. What
amazes me is that we ship Velocity product to Australia (!?) where
availability seems spotty compared to their US operations. Go figure.
p.s. When last I checked, Finland had a postal limit of 79 inches which
is smaller than a rim. Shipping via small-packet service (UPS, FedEx,
DHL) is considerably more expensive.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
|
| | | |
Date: 15 Sep 2007 13:16:37
From: A Muzi
Subject: Re: Cracks and spoke tension
|
>>>> jim beam wrote:
>>>>> and what is /your/ spoke tension???
>>> Chalo wrote:
>>>> I'll venture a guess: too high for Mavic's overcooked crappy alloy!
>>>> (But probably not too high for a better-made rim.)
>> jim beam wrote:
>>> the only mavic rim i've ever succeeded in cracking is one with spoke
>>> tension > 175N [off the end of the scale for my park tensiometer]. it's
>>> a single eyelet x517 and i weigh #205+. perversely, i don't consider
>>> this the result of "overcooked crappy alloy".
> Chalo wrote:
>> Do you mean 175kgf?
jim beam wrote:
> yes!
> Chalo wrote:
>> Most of Mavic's rims use 6106 aluminum-- just about the weakest of the
>> 6000 series--
jim beam wrote:
> any idea what their "maxtal" alloy is?
> Chalo wrote:
>> in order to get a sharp looking finish on the
>> extrusion.
jim beam wrote:
> that bit can't be true - they anodize it and that covers a multitude of
> sins.
> Chalo wrote:
>> For using some of the softest structural alloy money can
>> buy, their rims sure don't seem very ductile. I believe they do some
>> monkey business with heat treatment in an attempt to buy back the
>> hardness sacrificed in using a weak, soft alloy. Thus they get spoke
>> holes that crack and sidewalls from which segments break off. I have
>> seen these things happen much more often with Adidas-Salomon-Mavic
>> rims than with all other rims combined.
jim beam wrote:
> and most other rims weigh more. what about d.t. rims - they're
> weight/feature/performance competitive. have you tried those?
> Chalo wrote:
>> Paradoxically, they seem to do this aggressive heat treatment _before_
>> welding, which means they get the worst of both the soft material in
>> the weld and the brittle material elsewhere in the rim.
jim beam wrote:
> why not declare this a "bash mavic" weekend and be done with it?
Weekend? Ongoing for years! It'll probably span the whole century. Or
maybe just Mavic's lifetime, now that we have better alternate rims.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
|
| | | | |
Date: 15 Sep 2007 22:10:30
From:
Subject: Re: Cracks and spoke tension
|
Andrew Muzi writes:
>> why not declare this a "bash mavic" weekend and be done with it?
> Weekend? Ongoing for years! It'll probably span the whole century.
> Or maybe just Mavic's lifetime, now that we have better alternate
> rims.
It's been that ever since Solomon Ski bought the Mavic. All downhill,
and not even a slalom.
Jobst Brandt
|
| | | | |
Date: 15 Sep 2007 13:41:55
From: Ben C
Subject: Re: Cracks and spoke tension
|
On 2007-09-15, A Muzi <am@yellowjersey.org > wrote:
>>>>> jim beam wrote:
[...]
> jim beam wrote:
>> why not declare this a "bash mavic" weekend and be done with it?
>
> Weekend? Ongoing for years! It'll probably span the whole century. Or
> maybe just Mavic's lifetime, now that we have better alternate rims.
Well my cracked rim was a Rigida. And the Mavic I replaced it with is
holding up fine so far.
|
| |
Date: 15 Sep 2007 01:44:39
From: Chalo
Subject: Re: Cracks and spoke tension
|
jim beam wrote:
>
> Colin Campbell wrote:
> >
> > I have a silver 32 spoke Open Pro sitting in my garage with 10 cracked
> > spoke holes. I had to replace a blue anodized Open Pro that suffered a
> > crack at one spoke hole. The new wheel popped three spokes before the
> > LBS started noticing the cracks; then careful visual inspection showed
> > the ten cracks.
>
> > Very disappointing!
>
> and what is /your/ spoke tension???
I'll venture a guess: too high for Mavic's overcooked crappy alloy!
(But probably not too high for a better-made rim.)
Chalo
|
| | |
Date: 14 Sep 2007 19:35:15
From: jim beam
Subject: Re: Cracks and spoke tension
|
Chalo wrote:
> jim beam wrote:
>> Colin Campbell wrote:
>>> I have a silver 32 spoke Open Pro sitting in my garage with 10 cracked
>>> spoke holes. I had to replace a blue anodized Open Pro that suffered a
>>> crack at one spoke hole. The new wheel popped three spokes before the
>>> LBS started noticing the cracks; then careful visual inspection showed
>>> the ten cracks.
>>> Very disappointing!
>> and what is /your/ spoke tension???
>
> I'll venture a guess: too high for Mavic's overcooked crappy alloy!
> (But probably not too high for a better-made rim.)
>
> Chalo
>
the only mavic rim i've ever succeeded in cracking is one with spoke
tension > 175N [off the end of the scale for my park tensiometer]. it's
a single eyelet x517 and i weigh #205+. perversely, i don't consider
this the result of "overcooked crappy alloy".
|
| |
Date: 14 Sep 2007 13:42:13
From: Ron Ruff
Subject: Re: Cracks and spoke tension
|
On Sep 14, 2:35 am, joakim.majan...@luukku.com wrote:
> If this rim fails, which low profile low cost tubular rim would you
> recommend?
If you are willing to increase the profile a bit, the Velocity Escape
(20mm tall, 400g) or the Nio25T (25mm tall, 435g... made by Kinlin who
builds rims for Rolf and AC) are both solid rims.
|
| |
Date: 14 Sep 2007 07:15:09
From:
Subject: Re: Cracks and spoke tension
|
On 14 syys, 16:32, jim beam <spamvor...@bad.example.net > wrote:
> how do you know those are the numbers if you're not using a
> tensiometer??? you sound like a mechanic that thinks he can judge
> torque - it just isn't true.
I have measured the tensions from the previous rim using a sound
analyser (well actually only a program on laptop), which can detect
the harmonic frequencies. Then you need to know the free length and
the specific weight of the spoke in order to calculate the tension.
You can actually find two or three different frequencies for each
spoke (from rim to hub, from rim to first crossing etc.). Some
background: http://www.bikexprt.com/bicycle/pitcheqn.htm
Certainly more accurate than a 60 =80 tensiometer, which is of cource
accurate enough for this purpose, but too clumsy. Maybe I should
measure the new wheel as well.
When you have a reference wheels with 1000 N and 1300 N, you can
easily detect (by feeling or pinging the spoke) that the tension is
somewhere around 1300 N, but clearly more than 1000 N, since that's a
huge difference. In my old wheel the left side was around 700 N, which
is again easy to judge as far less than 1000 N.
I'm not saying I can feel the difference of 1000 and 1100 N, but I
don't believe that 10% error can be the cause of a rim failure of a
good rim.
Torque is a totally different thing, since you can't measure or feel
it after you have once tightened.
Joakim
|
| | |
Date: 14 Sep 2007 18:27:49
From: jim beam
Subject: Re: Cracks and spoke tension
|
joakim.majander@luukku.com wrote:
> On 14 syys, 16:32, jim beam <spamvor...@bad.example.net> wrote:
>
>> how do you know those are the numbers if you're not using a
>> tensiometer??? you sound like a mechanic that thinks he can judge
>> torque - it just isn't true.
>
> I have measured the tensions from the previous rim using a sound
> analyser (well actually only a program on laptop), which can detect
> the harmonic frequencies. Then you need to know the free length and
> the specific weight of the spoke in order to calculate the tension.
> You can actually find two or three different frequencies for each
> spoke (from rim to hub, from rim to first crossing etc.). Some
> background: http://www.bikexprt.com/bicycle/pitcheqn.htm
that's very interesting.
> Certainly more accurate than a 60 � tensiometer, which is of cource
> accurate enough for this purpose, but too clumsy. Maybe I should
> measure the new wheel as well.
won't hurt.
>
> When you have a reference wheels with 1000 N and 1300 N, you can
> easily detect (by feeling or pinging the spoke) that the tension is
> somewhere around 1300 N, but clearly more than 1000 N, since that's a
> huge difference.
sure, if the references are correct.
> In my old wheel the left side was around 700 N, which
> is again easy to judge as far less than 1000 N.
>
> I'm not saying I can feel the difference of 1000 and 1100 N, but I
> don't believe that 10% error can be the cause of a rim failure of a
> good rim.
why not? if you happen to be on the light side of rim thickness, and on
the high side of spoke tension, i don't see any reason you can't get
into the fatigue zone.
also, don't forget that manufacturer spec spoke tensions are for a naked
rim, not one with an inflated tire - inflated tires reduce spoke
tension, so if you tensioned /with/ an inflated tire, tension will be
too high.
>
> Torque is a totally different thing, since you can't measure or feel
> it after you have once tightened.
no, but many purport to be able to feel it /during/ tightening.
|
| |
Date: 14 Sep 2007 06:26:52
From:
Subject: Re: Cracks and spoke tension
|
On 14 syys, 15:58, jim beam <spamvor...@bad.example.net > wrote:
> excessive spoke tension. trying to determine spoke tension by judging
> the "taco" limit is at best imprecise and always leads to excess.
>
> build with a tensiometer and use the manufacturer specified tension.
> that allows you to achieve that narrow zone of tension that avoids both
> problems.
Haven't used the taco limit, just said that it hasn't been reached. I
measured the tension by sound pitch from the old rim a year or two
before it failed. With the old rim I increased the tension bit by bit
until unscrewing problem was solved. I also have one Mavic clincher
rim that suffers from unscrewing.
The current rim I tensioned to about the same tension as the old one
(a bit more tension than in the clincher rim) just by feel.
I'm not going to buy a tensiometer, since I build a new wheel only
when the previous one fails, which hopefully means once in 10-20
years. The front rim from Wolber is now 17 years and well over 30 000
km old and hasn't needed any care (it has a deeper profile and 1000 N
tension).
It's easy to notice the difference between 1000 and 1300 N just by
feel. 1000 N for the right side of rear wheel just is not enough for
my rims.
Joakim
|
| | |
Date: 14 Sep 2007 06:32:48
From: jim beam
Subject: Re: Cracks and spoke tension
|
joakim.majander@luukku.com wrote:
> On 14 syys, 15:58, jim beam <spamvor...@bad.example.net> wrote:
>
>> excessive spoke tension. trying to determine spoke tension by judging
>> the "taco" limit is at best imprecise and always leads to excess.
>>
>> build with a tensiometer and use the manufacturer specified tension.
>> that allows you to achieve that narrow zone of tension that avoids both
>> problems.
>
> Haven't used the taco limit, just said that it hasn't been reached. I
> measured the tension by sound pitch from the old rim a year or two
> before it failed. With the old rim I increased the tension bit by bit
> until unscrewing problem was solved. I also have one Mavic clincher
> rim that suffers from unscrewing.
>
> The current rim I tensioned to about the same tension as the old one
> (a bit more tension than in the clincher rim) just by feel.
>
> I'm not going to buy a tensiometer, since I build a new wheel only
> when the previous one fails, which hopefully means once in 10-20
> years. The front rim from Wolber is now 17 years and well over 30 000
> km old and hasn't needed any care (it has a deeper profile and 1000 N
> tension).
>
> It's easy to notice the difference between 1000 and 1300 N just by
> feel.
how do you know those are the numbers if you're not using a
tensiometer??? you sound like a mechanic that thinks he can judge
torque - it just isn't true. buy a $60 tensiometer. set your wheels
accurately. then sell it for $50. end of problem.
> 1000 N for the right side of rear wheel just is not enough for
> my rims.
>
> Joakim
>
|
| | | |
Date: 14 Sep 2007 19:10:15
From: John Thompson
Subject: Re: Cracks and spoke tension
|
On 2007-09-14, jim beam <spamvortex@bad.example.net > wrote:
> how do you know those are the numbers if you're not using a
> tensiometer???
How do you jknow your tensiometer is properly calibrated? That was the
problem we ran into at Trek when we started building wheels. I was
recalibrating tensiometers for the builders several times a day. Hard to
get anything else done, sometimes.
--
John (john@os2.dhs.org)
|
| | | | |
Date: 14 Sep 2007 18:19:11
From: jim beam
Subject: Re: Cracks and spoke tension
|
John Thompson wrote:
> On 2007-09-14, jim beam <spamvortex@bad.example.net> wrote:
>
>> how do you know those are the numbers if you're not using a
>> tensiometer???
>
> How do you jknow your tensiometer is properly calibrated? That was the
> problem we ran into at Trek when we started building wheels. I was
> recalibrating tensiometers for the builders several times a day. Hard to
> get anything else done, sometimes.
>
that may be, but personally, i find it hard to believe there was /that/
much of a problem. what kind of tensiometer were you using? why use
one so unreliable?
and one thing is for sure - /not/ using a tensiometer is guaranteed to
give you inconsistent results.
|
| | | | | |
Date: 15 Sep 2007 20:04:20
From: John Thompson
Subject: Re: Cracks and spoke tension
|
On 2007-09-15, jim beam <spamvortex@bad.example.net > wrote:
> John Thompson wrote:
>> On 2007-09-14, jim beam <spamvortex@bad.example.net> wrote:
>>
>>> how do you know those are the numbers if you're not using a
>>> tensiometer???
>> How do you jknow your tensiometer is properly calibrated? That was the
>> problem we ran into at Trek when we started building wheels. I was
>> recalibrating tensiometers for the builders several times a day. Hard to
>> get anything else done, sometimes.
> that may be, but personally, i find it hard to believe there was /that/
> much of a problem. what kind of tensiometer were you using? why use
> one so unreliable?
I believe they were from Wheelsmith. Basically, a spring-loaded run-out
gauge to measure deflection in a segment of spoke. When you're building
hundreds of wheels a day, they do go out of calibration more quickly
than in a local shop.
--
John (john@os2.dhs.org)
|
| | | | | | |
Date: 16 Sep 2007 08:25:47
From: jim beam
Subject: Re: Cracks and spoke tension
|
John Thompson wrote:
> On 2007-09-15, jim beam <spamvortex@bad.example.net> wrote:
>
>> John Thompson wrote:
>>> On 2007-09-14, jim beam <spamvortex@bad.example.net> wrote:
>>>
>>>> how do you know those are the numbers if you're not using a
>>>> tensiometer???
>
>>> How do you jknow your tensiometer is properly calibrated? That was the
>>> problem we ran into at Trek when we started building wheels. I was
>>> recalibrating tensiometers for the builders several times a day. Hard to
>>> get anything else done, sometimes.
>
>> that may be, but personally, i find it hard to believe there was /that/
>> much of a problem. what kind of tensiometer were you using? why use
>> one so unreliable?
>
> I believe they were from Wheelsmith. Basically, a spring-loaded run-out
> gauge to measure deflection in a segment of spoke. When you're building
> hundreds of wheels a day, they do go out of calibration more quickly
> than in a local shop.
>
they might, but hundreds of wheels a day and only one tensiometer?
for only 100 wheels and 8 hours, that's one wheel every 4.8 minutes. i
would have thought a more heavy duty tool appropriate to that application.
|
| | | | | | |
Date: 16 Sep 2007 04:50:30
From:
Subject: Re: Cracks and spoke tension
|
John Thompson writes:
>>>> how do you know those are the numbers if you're not using a
>>>> tensiometer???
>>> How do you jknow your tensiometer is properly calibrated? That was
>>> the problem we ran into at Trek when we started building wheels. I
>>> was recalibrating tensiometers for the builders several times a
>>> day. Hard to get anything else done, sometimes.
>> that may be, but personally, i find it hard to believe there was
>> /that/ much of a problem. what kind of tensiometer were you using?
>> why use one so unreliable?
> I believe they were from Wheelsmith. Basically, a spring-loaded
> run-out gauge to measure deflection in a segment of spoke. When
> you're building hundreds of wheels a day, they do go out of
> calibration more quickly than in a local shop.
I've been watching this thread and cannot see what goes out of
calibration on these devices. Their springs are not highly stressed
and there are no wearing parts. What is it with these instruments.
None of the ones I've had in hand has a propensity to lose
calibration.
'splain!
Jobst Brandt
|
| | | | | | | |
Date: 16 Sep 2007 07:37:13
From: jim beam
Subject: Re: Cracks and spoke tension
|
jobst.brandt@stanfordalumni.org wrote:
> John Thompson writes:
>
>>>>> how do you know those are the numbers if you're not using a
>>>>> tensiometer???
>
>>>> How do you jknow your tensiometer is properly calibrated? That was
>>>> the problem we ran into at Trek when we started building wheels. I
>>>> was recalibrating tensiometers for the builders several times a
>>>> day. Hard to get anything else done, sometimes.
>
>>> that may be, but personally, i find it hard to believe there was
>>> /that/ much of a problem. what kind of tensiometer were you using?
>>> why use one so unreliable?
>
>> I believe they were from Wheelsmith. Basically, a spring-loaded
>> run-out gauge to measure deflection in a segment of spoke. When
>> you're building hundreds of wheels a day, they do go out of
>> calibration more quickly than in a local shop.
>
> I've been watching this thread and cannot see what goes out of
> calibration on these devices. Their springs are not highly stressed
> and there are no wearing parts.
well, the mounting points can be subject to wear, but that's more an
issue for used wheels where road grit can be abrasive. not much of a
problem on new builds, i agree.
> What is it with these instruments.
> None of the ones I've had in hand has a propensity to lose
> calibration.
>
> 'splain!
>
> Jobst Brandt
|
| |
Date: 14 Sep 2007 05:58:32
From: jim beam
Subject: Re: Cracks and spoke tension
|
joakim.majander@luukku.com wrote:
> I just noticed cracks around ALL right hand eylets on my Mavic Reflex
> tubular rim (32 hole, grey non-anodised). The cracks look similar to
> these: http://web.onetel.net.uk/~davidwgreen/rimpics/4.JPG but some of
> them are from side to side and at least one was all the way to the
> "corner" where the side begins.
>
> The rim is just a couple of years old and hasn't been ridden more than
> 5000 km. I build it myself using old spokes (DT 2/1.8 mm) and rather
> high tension (the old rim had ~1300 N, this is probably about the
> same, not yet on the "taco" limit) for right hand side. I weigh 82 kg
> and ride on quite smooth roads.
>
> The old rim was an anodised GP4, which I rode about 20 000 km until
> one eylet was pulled through the rim. I hoped, that this new rim would
> be better....
>
> Am I just unlucky, is this a poor rim type or is the tension I use too
> much? With lower tension I have had lot of problems with self
> loosening left side spokes, which required wrenching every 100-200 km.
> This wheel has stayed true.
>
> If this rim fails, which low profile low cost tubular rim would you
> recommend?
>
> Joakim
>
excessive spoke tension. trying to determine spoke tension by judging
the "taco" limit is at best imprecise and always leads to excess.
build with a tensiometer and use the manufacturer specified tension.
that allows you to achieve that narrow zone of tension that avoids both
problems.
|
| |
Date: 14 Sep 2007 05:25:58
From: Qui si parla Campagnolo-www.vecchios.com
Subject: Re: Cracks and spoke tension
|
On Sep 14, 2:35 am, joakim.majan...@luukku.com wrote:
> I just noticed cracks around ALL right hand eylets on my Mavic Reflex
> tubular rim (32 hole, grey non-anodised). The cracks look similar to
> these:http://web.onetel.net.uk/~davidwgreen/rimpics/4.JPGbut some of
> them are from side to side and at least one was all the way to the
> "corner" where the side begins.
>
> The rim is just a couple of years old and hasn't been ridden more than
> 5000 km. I build it myself using old spokes (DT 2/1.8 mm) and rather
> high tension (the old rim had ~1300 N, this is probably about the
> same, not yet on the "taco" limit) for right hand side. I weigh 82 kg
> and ride on quite smooth roads.
>
> The old rim was an anodised GP4, which I rode about 20 000 km until
> one eylet was pulled through the rim. I hoped, that this new rim would
> be better....
>
> Am I just unlucky, is this a poor rim type or is the tension I use too
> much?
Number 2 is my guess. mavic eyeleted rims do not like lots of
tension. 100 kgf, 105 or so max.
With lower tension I have had lot of problems with self
> loosening left side spokes, which required wrenching every 100-200 km.
> This wheel has stayed true.
>
> If this rim fails, which low profile low cost tubular rim would you
> recommend?
>
> Joakim
Velocity Escape..not box section but nice rim.
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Date: 14 Sep 2007 02:54:30
From:
Subject: Re: Cracks and spoke tension
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On Sep 14, 3:35 am, joakim.majan...@luukku.com wrote:
> I just noticed cracks around ALL right hand eylets on my Mavic Reflex
> tubular rim (32 hole, grey non-anodised). The cracks look similar to
> these:http://web.onetel.net.uk/~davidwgreen/rimpics/4.JPGbut some of
> them are from side to side and at least one was all the way to the
> "corner" where the side begins.
>
> The rim is just a couple of years old and hasn't been ridden more than
> 5000 km. I build it myself using old spokes (DT 2/1.8 mm) and rather
> high tension (the old rim had ~1300 N, this is probably about the
> same, not yet on the "taco" limit) for right hand side. I weigh 82 kg
> and ride on quite smooth roads.
>
> The old rim was an anodised GP4, which I rode about 20 000 km until
> one eylet was pulled through the rim. I hoped, that this new rim would
> be better....
>
> Am I just unlucky, is this a poor rim type or is the tension I use too
> much? With lower tension I have had lot of problems with self
> loosening left side spokes, which required wrenching every 100-200 km.
> This wheel has stayed true.
>
> If this rim fails, which low profile low cost tubular rim would you
> recommend?
>
> Joakim
The Mavic Classics Pro wheel set of several years ago used, I presume,
their 32 hole Reflex tubular rims. The below linked specification
sheet indicates spoke tension of just 92-112 Kgf (10N = 1Kgf ).
http://www.tech-mavic.com/tech-mavic/technical_manual/data/tech-mavic/uk/sources/Produits/ROUTE/Roues/ClassicsProCD/ClasProCDSpareParts.pdf
--
Spike
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Date: 14 Sep 2007 04:19:33
From: Ben C
Subject: Re: Cracks and spoke tension
|
On 2007-09-14, joakim.majander@luukku.com <joakim.majander@luukku.com > wrote:
> I just noticed cracks around ALL right hand eylets on my Mavic Reflex
> tubular rim (32 hole, grey non-anodised). The cracks look similar to
> these: http://web.onetel.net.uk/~davidwgreen/rimpics/4.JPG but some of
> them are from side to side and at least one was all the way to the
> "corner" where the side begins.
>
> The rim is just a couple of years old and hasn't been ridden more than
> 5000 km. I build it myself using old spokes (DT 2/1.8 mm) and rather
> high tension (the old rim had ~1300 N, this is probably about the
> same, not yet on the "taco" limit) for right hand side. I weigh 82 kg
> and ride on quite smooth roads.
>
> The old rim was an anodised GP4, which I rode about 20 000 km until
> one eylet was pulled through the rim. I hoped, that this new rim would
> be better....
>
> Am I just unlucky, is this a poor rim type or is the tension I use too
> much? With lower tension I have had lot of problems with self
> loosening left side spokes, which required wrenching every 100-200 km.
> This wheel has stayed true.
High tension is thought to be what causes those cracks.
You could try less tension and linseed or threadlock. This is not a
solution for the purists since in principle spokes shouldn't ever go
slack enough to unscrew. All the same it might work, and the only other
option is to find a better rim, which seems to me a bit of a lottery.
I'd probably try a different rim anyway, use linseed (which works as a
fairly mild threadlock), and a bit less tension.
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Date: 14 Sep 2007 09:14:39
From: Chalo
Subject: Re: Cracks and spoke tension
|
joakim.majan...@luukku.com wrote:
>
> I just noticed cracks around ALL right hand eylets on my Mavic Reflex
> tubular rim (32 hole, grey non-anodised). The cracks look similar to
> these:http://web.onetel.net.uk/~davidwgreen/rimpics/4.JPGbut some of
> them are from side to side and at least one was all the way to the
> "corner" where the side begins.
Mavic rims made since about 1990 are well known for having problems
with cracking at the spoke holes and at the sidewall root.
> Am I just unlucky, is this a poor rim type or is the tension I use too
> much? With lower tension I have had lot of problems with self
> loosening left side spokes, which required wrenching every 100-200 km.
> This wheel has stayed true.
My guess is that the tension you used was too much _because_ it's a
poor rim.
I have no recommendation for a good tubie rim because I don't use
them. If you need to use high spoke tension, be aware that aero
section rims are better at withstanding high spoke tension, generally
speaking.
Chalo
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Date: 14 Sep 2007 07:31:05
From: Peter Cole
Subject: Re: Cracks and spoke tension
|
Chalo wrote:
> joakim.majan...@luukku.com wrote:
>> I just noticed cracks around ALL right hand eylets on my Mavic Reflex
>> tubular rim (32 hole, grey non-anodised). The cracks look similar to
>> these:http://web.onetel.net.uk/~davidwgreen/rimpics/4.JPGbut some of
>> them are from side to side and at least one was all the way to the
>> "corner" where the side begins.
>
> Mavic rims made since about 1990 are well known for having problems
> with cracking at the spoke holes and at the sidewall root.
>
>> Am I just unlucky, is this a poor rim type or is the tension I use too
>> much? With lower tension I have had lot of problems with self
>> loosening left side spokes, which required wrenching every 100-200 km.
>> This wheel has stayed true.
>
> My guess is that the tension you used was too much _because_ it's a
> poor rim.
>
> I have no recommendation for a good tubie rim because I don't use
> them. If you need to use high spoke tension, be aware that aero
> section rims are better at withstanding high spoke tension, generally
> speaking.
I had the exact same problem with the clincher version of that rim. I
agree with Chalo, that it was a poor rim that wouldn't take the tension
required to keep the spokes from unscrewing. I went to Open Pros after 2
Reflex failures and didn't have the same problems.
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Date: 14 Sep 2007 16:42:47
From: Colin Campbell
Subject: Re: Cracks and spoke tension
|
Peter Cole wrote:
> Chalo wrote:
>> joakim.majan...@luukku.com wrote:
>>> I just noticed cracks around ALL right hand eylets on my Mavic Reflex
>>> tubular rim (32 hole, grey non-anodised). The cracks look similar to
>>> these:http://web.onetel.net.uk/~davidwgreen/rimpics/4.JPGbut some of
>>> them are from side to side and at least one was all the way to the
>>> "corner" where the side begins.
>>
>> Mavic rims made since about 1990 are well known for having problems
>> with cracking at the spoke holes and at the sidewall root.
>>
>>> Am I just unlucky, is this a poor rim type or is the tension I use too
>>> much? With lower tension I have had lot of problems with self
>>> loosening left side spokes, which required wrenching every 100-200 km.
>>> This wheel has stayed true.
>>
>> My guess is that the tension you used was too much _because_ it's a
>> poor rim.
>>
>> I have no recommendation for a good tubie rim because I don't use
>> them. If you need to use high spoke tension, be aware that aero
>> section rims are better at withstanding high spoke tension, generally
>> speaking.
>
> I had the exact same problem with the clincher version of that rim. I
> agree with Chalo, that it was a poor rim that wouldn't take the tension
> required to keep the spokes from unscrewing. I went to Open Pros after 2
> Reflex failures and didn't have the same problems.
I have a silver 32 spoke Open Pro sitting in my garage with 10 cracked
spoke holes. I had to replace a blue anodized Open Pro that suffered a
crack at one spoke hole. The new wheel popped three spokes before the
LBS started noticing the cracks; then careful visual inspection showed
the ten cracks.
Very disappointing!
I bought a Trek bike last year in August, and stayed with Bontrager Race
Lite wheels, even though I was afraid of problems with a 22F, 24R setup.
I've actually had no problems, except that one spoke likes to loosen
up on the rear wheel.
I don't know when or if I'll try Mavic rims again.
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Date: 14 Sep 2007 18:18:27
From: jim beam
Subject: Re: Cracks and spoke tension
|
Colin Campbell wrote:
> Peter Cole wrote:
>> Chalo wrote:
>>> joakim.majan...@luukku.com wrote:
>>>> I just noticed cracks around ALL right hand eylets on my Mavic Reflex
>>>> tubular rim (32 hole, grey non-anodised). The cracks look similar to
>>>> these:http://web.onetel.net.uk/~davidwgreen/rimpics/4.JPGbut some of
>>>> them are from side to side and at least one was all the way to the
>>>> "corner" where the side begins.
>>>
>>> Mavic rims made since about 1990 are well known for having problems
>>> with cracking at the spoke holes and at the sidewall root.
>>>
>>>> Am I just unlucky, is this a poor rim type or is the tension I use too
>>>> much? With lower tension I have had lot of problems with self
>>>> loosening left side spokes, which required wrenching every 100-200 km.
>>>> This wheel has stayed true.
>>>
>>> My guess is that the tension you used was too much _because_ it's a
>>> poor rim.
>>>
>>> I have no recommendation for a good tubie rim because I don't use
>>> them. If you need to use high spoke tension, be aware that aero
>>> section rims are better at withstanding high spoke tension, generally
>>> speaking.
>>
>> I had the exact same problem with the clincher version of that rim. I
>> agree with Chalo, that it was a poor rim that wouldn't take the
>> tension required to keep the spokes from unscrewing. I went to Open
>> Pros after 2 Reflex failures and didn't have the same problems.
>
> I have a silver 32 spoke Open Pro sitting in my garage with 10 cracked
> spoke holes. I had to replace a blue anodized Open Pro that suffered a
> crack at one spoke hole. The new wheel popped three spokes before the
> LBS started noticing the cracks; then careful visual inspection showed
> the ten cracks.
>
> Very disappointing!
and what is /your/ spoke tension???
>
> I bought a Trek bike last year in August, and stayed with Bontrager Race
> Lite wheels, even though I was afraid of problems with a 22F, 24R setup.
> I've actually had no problems, except that one spoke likes to loosen up
> on the rear wheel.
>
> I don't know when or if I'll try Mavic rims again.
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Date: 14 Sep 2007 05:55:07
From: jim beam
Subject: Re: Cracks and spoke tension
|
Peter Cole wrote:
> Chalo wrote:
>> joakim.majan...@luukku.com wrote:
>>> I just noticed cracks around ALL right hand eylets on my Mavic Reflex
>>> tubular rim (32 hole, grey non-anodised). The cracks look similar to
>>> these:http://web.onetel.net.uk/~davidwgreen/rimpics/4.JPGbut some of
>>> them are from side to side and at least one was all the way to the
>>> "corner" where the side begins.
>>
>> Mavic rims made since about 1990 are well known for having problems
>> with cracking at the spoke holes and at the sidewall root.
>>
>>> Am I just unlucky, is this a poor rim type or is the tension I use too
>>> much? With lower tension I have had lot of problems with self
>>> loosening left side spokes, which required wrenching every 100-200 km.
>>> This wheel has stayed true.
>>
>> My guess is that the tension you used was too much _because_ it's a
>> poor rim.
>>
>> I have no recommendation for a good tubie rim because I don't use
>> them. If you need to use high spoke tension, be aware that aero
>> section rims are better at withstanding high spoke tension, generally
>> speaking.
>
> I had the exact same problem with the clincher version of that rim. I
> agree with Chalo, that it was a poor rim that wouldn't take the tension
> required to keep the spokes from unscrewing. I went to Open Pros after 2
> Reflex failures and didn't have the same problems.
did you use a tensiometer?
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Date: 14 Sep 2007 11:00:52
From: Peter Cole
Subject: Re: Cracks and spoke tension
|
jim beam wrote:
> Peter Cole wrote:
>> Chalo wrote:
>>> joakim.majan...@luukku.com wrote:
>>>> I just noticed cracks around ALL right hand eylets on my Mavic Reflex
>>>> tubular rim (32 hole, grey non-anodised). The cracks look similar to
>>>> these:http://web.onetel.net.uk/~davidwgreen/rimpics/4.JPGbut some of
>>>> them are from side to side and at least one was all the way to the
>>>> "corner" where the side begins.
>>>
>>> Mavic rims made since about 1990 are well known for having problems
>>> with cracking at the spoke holes and at the sidewall root.
>>>
>>>> Am I just unlucky, is this a poor rim type or is the tension I use too
>>>> much? With lower tension I have had lot of problems with self
>>>> loosening left side spokes, which required wrenching every 100-200 km.
>>>> This wheel has stayed true.
>>>
>>> My guess is that the tension you used was too much _because_ it's a
>>> poor rim.
>>>
>>> I have no recommendation for a good tubie rim because I don't use
>>> them. If you need to use high spoke tension, be aware that aero
>>> section rims are better at withstanding high spoke tension, generally
>>> speaking.
>>
>> I had the exact same problem with the clincher version of that rim. I
>> agree with Chalo, that it was a poor rim that wouldn't take the
>> tension required to keep the spokes from unscrewing. I went to Open
>> Pros after 2 Reflex failures and didn't have the same problems.
>
> did you use a tensiometer?
I didn't build that wheel, it was built by an experienced builder who
does/did have a tensiometer, I assume he used it.
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Date: 14 Sep 2007 18:18:35
From: jim beam
Subject: Re: Cracks and spoke tension
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> Chalo wrote:
>>>> joakim.majan...@luukku.com wrote:
>>>>> I just noticed cracks around ALL right hand eylets on my Mavic Reflex
>>>>> tubular rim (32 hole, grey non-anodised). The cracks look similar to
>>>>> these:http://web.onetel.net.uk/~davidwgreen/rimpics/4.JPGbut some of
>>>>> them are from side to side and at least one was all the way to the
>>>>> "corner" where the side begins.
>>>>
>>>> Mavic rims made since about 1990 are well known for having problems
>>>> with cracking at the spoke holes and at the sidewall root.
>>>>
>>>>> Am I just unlucky, is this a poor rim type or is the tension I use too
>>>>> much? With lower tension I have had lot of problems with self
>>>>> loosening left side spokes, which required wrenching every 100-200 km.
>>>>> This wheel has stayed true.
>>>>
>>>> My guess is that the tension you used was too much _because_ it's a
>>>> poor rim.
>>>>
>>>> I have no recommendation for a good tubie rim because I don't use
>>>> them. If you need to use high spoke tension, be aware that aero
>>>> section rims are better at withstanding high spoke tension, generally
>>>> speaking.
>>>
>>> I had the exact same problem with the clincher version of that rim. I
>>> agree with Chalo, that it was a poor rim that wouldn't take the
>>> tension required to keep the spokes from unscrewing. I went to Open
>>> Pros after 2 Reflex failures and didn't have the same problems.
>>
>> did you use a tensiometer?
>
> I didn't build that wheel, it was built by an experienced builder who
> does/did have a tensiometer, I assume he used it.
you /assume/? how convenient! dodge responsibility but try to
attribute a problem to something that you're merely guessing at!
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