SPOKE LENGTH IN NIPPLE

On Feb 3, 8:34*am, wrote:
Ben C? writes:
"erd" is simple enough - it's what "effective" means that's
unclear. *maybe that's why mavic call it "spoke support" - since
they clearly haven't read jobst's book and are untainted by its
terminological inexactitudes.
"erd" is calculation input. *you decide the result you want it to
give.
But the output is the spoke length, if I knew the spoke length I
could calculate the ERD, but I don't know the spoke length, so
which ERD do I choose?
You decide what point in the rim cross-section you want the spoke
ends to reach. Then you measure the distance from there to the
corresponding opposite point on the other side. That's the ERD.
My point was, surely it's defined?
It is defined, but in terms of what you personally want! This is
what Jim Beam is saying, also Damon Rinard on the link posted
earlier.

* * *http://sheldonbrown.com/rinard/spocalc.htm

# * * "Effective Rim Diameter (ERD) is the diameter on which you want
# * * the ends of the spokes to lie. *Most people prefer it near the
# * * end of the spoke nipple."

But, in Sheldon's glossary, a slightly different definition:

* * *http://www.sheldonbrown.com/gloss_e-f.html

# * * "Effective Rim Diameter. *This is the rim diameter measured at
# * * the nipple seats in the spoke holes, plus the thickness of the
# * * two nipple heads. *The E.R.D. is needed for calculating the
# * * correct spoke length."

This second definition implies ERD is defined as distance between
nipple seats. *But according to the first definition it's only that
distance if _that's how long you personally like your spokes_. *Some
people might add 3mm to that.

Not so. *Both of these are essentially the distance over spoke nipple
ends measured across the diameter of the rim. *Only the wording is
different.

Actually, I'm ****ed and I'm going to bed, thoroughly confused
about whether a manufacturers ERD is to be trusted or is just a
number they dreamed up.
It would be much better if manufacturers always just quoted spoke
support diameter. Then you know what the number actually is supposed
to correspond to and can add 3mm if you like longer spokes, or not
if you don't.

That is not my perception of the dimension. *You can do anything you
want with an ERD that spans the tops of spoke nipples, the place where
spokes should reach from the hub.

If 3mm ended up getting added twice due to these misunderstandings
the spokes could be too long by enough to cause a real problem.

3mm is roughly the height of a spoke nipple head, so it needs to be
added twice to the bed of the rim support surface, there being two
spoke nipples on the diameter.

Jobst Brandt- Hide quoted text -

- Show quoted text -

add the 3mm to the spke nipple HEAD? add 3mm to the spoke nipple END?
WHY NOT add 4mm just to be sure? only the WORDS are different?
now I understand why people complain about figuring taxs. then add the
1.5 mm fiddle factors...
not to mention AGAIN that the gathered experts refuse the question why
the spoke end should reach so far into the rim that the threading
bottoms out over at the spoke shaft....

Ben C wrote:
On 2008-02-03, datakoll wrote:
On Feb 2, 9:39�pm, datakoll wrote:
[...]
ach did that again JB! (ERD/2)-3mm=spoke length

Of course not! To work out spoke length from ERD you need to know hub
dimensions and number of crossings and do the proper formula, which is
more complicated than that one.

The question is what's your manufacturer quoting. If it's Mavic, they
quote spoke support diameter, so just use that. Don't subtract 3mm.

If it's someone else and they quote "ERD" you have a problem because who
knows whether they added a bit to the spoke support diameter to get ERD
or not. It depends on their personal preference.

Best advice is just go with what the rim manufacturer quotes. If they
think you need spokes a little bit longer than you do just live with it.
If you add/subtract 3mm trying to second-guess what they mean by ERD you
risk doubling the error.

well said.

On 2008-02-03, wrote:
Ben C? writes:
[...]
http://sheldonbrown.com/rinard/spocalc.htm

# "Effective Rim Diameter (ERD) is the diameter on which you want
# the ends of the spokes to lie. Most people prefer it near the
# end of the spoke nipple."

But, in Sheldon's glossary, a slightly different definition:

http://www.sheldonbrown.com/gloss_e-f.html

# "Effective Rim Diameter. This is the rim diameter measured at
# the nipple seats in the spoke holes, plus the thickness of the
# two nipple heads. The E.R.D. is needed for calculating the
# correct spoke length."

This second definition implies ERD is defined as distance between
nipple seats. But according to the first definition it's only that
distance if _that's how long you personally like your spokes_. Some
people might add 3mm to that.

Not so. Both of these are essentially the distance over spoke nipple
ends measured across the diameter of the rim. Only the wording is
different.

You're right, I missed the bit "plus the thickness of the two nipple
heads". The definitions are exactly the same, and the same as one you
gave earlier.

Sorry for being so stupid.

datakoll Wrote:
On Feb 3, 8:34*am, wrote:
Ben C? writes:
"erd" is simple enough - it's what "effective" means that's
unclear. *maybe that's why mavic call it "spoke support" -
since
they clearly haven't read jobst's book and are untainted by
its
terminological inexactitudes.
"erd" is calculation input. *you decide the result you want it
to
give.
But the output is the spoke length, if I knew the spoke length I
could calculate the ERD, but I don't know the spoke length, so
which ERD do I choose?
You decide what point in the rim cross-section you want the spoke
ends to reach. Then you measure the distance from there to the
corresponding opposite point on the other side. That's the ERD.
My point was, surely it's defined?
It is defined, but in terms of what you personally want! This is
what Jim Beam is saying, also Damon Rinard on the link posted
earlier.

* * *http://sheldonbrown.com/rinard/spocalc.htm

# * * "Effective Rim Diameter (ERD) is the diameter on which you
want
# * * the ends of the spokes to lie. *Most people prefer it near the
# * * end of the spoke nipple."

But, in Sheldon's glossary, a slightly different definition:

* * *http://www.sheldonbrown.com/gloss_e-f.html

# * * "Effective Rim Diameter. *This is the rim diameter measured at
# * * the nipple seats in the spoke holes, plus the thickness of the
# * * two nipple heads. *The E.R.D. is needed for calculating the
# * * correct spoke length."

This second definition implies ERD is defined as distance between
nipple seats. *But according to the first definition it's only
that
distance if _that's how long you personally like your spokes_.
*Some
people might add 3mm to that.

Not so. *Both of these are essentially the distance over spoke
nipple
ends measured across the diameter of the rim. *Only the wording is
different.

Actually, I'm ****ed and I'm going to bed, thoroughly confused
about whether a manufacturers ERD is to be trusted or is just a
number they dreamed up.
It would be much better if manufacturers always just quoted spoke
support diameter. Then you know what the number actually is
supposed
to correspond to and can add 3mm if you like longer spokes, or not
if you don't.

That is not my perception of the dimension. *You can do anything you
want with an ERD that spans the tops of spoke nipples, the place
where
spokes should reach from the hub.

If 3mm ended up getting added twice due to these misunderstandings
the spokes could be too long by enough to cause a real problem.

3mm is roughly the height of a spoke nipple head, so it needs to be
added twice to the bed of the rim support surface, there being two
spoke nipples on the diameter.

Jobst Brandt- Hide quoted text -

- Show quoted text -

add the 3mm to the spke nipple HEAD? add 3mm to the spoke nipple END?
WHY NOT add 4mm just to be sure? only the WORDS are different?
now I understand why people complain about figuring taxs. then add the
1.5 mm fiddle factors...
not to mention AGAIN that the gathered experts refuse the question why
the spoke end should reach so far into the rim that the threading
bottoms out over at the spoke shaft....
Look at the illustration on the Rinard section of Sheldon Brown's site
that vaious people told you about. This illustration includes using the
nipples you will use and the rim you will use (No calculations of
estimates). You position the spokes in the nipples as you would like
them to end up after final tensioning. The length you get is the
Effective Rim Diameter. If you follow the illustration and the steps
given, you will have the actual ERD fro the particular rim and nipple
combination. When you plug in that ERD into your spoke calcualtion you
will get the correct answer for spoke lengths every time and with every
crossing pattern.


--
daveornee

On Feb 3, 10:00Â*am, jim beam wrote:
Ben C wrote:
On 2008-02-03, datakoll wrote:
On Feb 2, 9:39�pm, datakoll wrote:
[...]
ach did that again JB! Â*(ERD/2)-3mm=spoke length

Of course not! To work out spoke length from ERD you need to know hub
dimensions and number of crossings and do the proper formula, which is
more complicated than that one.

The question is what's your manufacturer quoting. If it's Mavic, they
quote spoke support diameter, so just use that. Don't subtract 3mm.

If it's someone else and they quote "ERD" you have a problem because who
knows whether they added a bit to the spoke support diameter to get ERD
or not. It depends on their personal preference.

Best advice is just go with what the rim manufacturer quotes. If they
think you need spokes a little bit longer than you do just live with it.
If you add/subtract 3mm trying to second-guess what they mean by ERD you
risk doubling the error.

well said.- Hide quoted text -

- Show quoted text -

what is SPOKE SUPPORT DIAMETER? What's Mavic's address for their
definiton of SSD?

On 2008-02-03, datakoll wrote:
On Feb 3, 10:00*am, jim beam wrote:
Ben C wrote:
[...]
The question is what's your manufacturer quoting. If it's Mavic, they
quote spoke support diameter, so just use that. Don't subtract 3mm.
[...]
what is SPOKE SUPPORT DIAMETER?

I assume it means diameter between the points on the rim where the
nipples sit.

i.e. ERD (as defined by Brandt and Sheldon) minus about 3mm.

But you ask a good question, because I don't know for sure what they
mean by it.

What's Mavic's address for their definiton of SSD?

Don't know, but if you get hold of them and find out the exact
definition of SSD, post it here.

On Feb 3, 1:31*pm, Ben C wrote:
On 2008-02-03, datakoll wrote:

On Feb 3, 10:00*am, jim beam wrote:
Ben C wrote:
[...]
The question is what's your manufacturer quoting. If it's Mavic, they
quote spoke support diameter, so just use that. Don't subtract 3mm.
[...]
what is SPOKE SUPPORT DIAMETER?

I assume it means diameter between the points on the rim where the
nipples sit.

i.e. ERD (as defined by Brandt and Sheldon) minus about 3mm.

But you ask a good question, because I don't know for sure what they
mean by it.

What's Mavic's address for their definiton of SSD?

Don't know, but if you get hold of them and find out the exact
definition of SSD, post it here.

Spoke Calc can incorporate a spoke/nipple/rim blowup showing where the
ERD is, how many spoke threads the ERD uses, how many are left for
wear and estimate wear, elbow stretch, anomaly and relating the odd
happenings to spoke thread availability when ERD is used as a real
time spoke end calculation (without deduction).

On Feb 5, 11:54*pm, jim beam wrote:
datakoll wrote:

an oversimplification form an engineer ?
I call for truth in spoke calc and the engineer cries out for
continued obfucstaion?
A graphic is an educational tool not oly for the consumer but MO and
LBS staff unable to enter data into spoke clcs and ship correct
lengths.
THE ERD DOESN'T WORK! THE ERD USES 90% of available spoke threading
just to satisfy GOD ERD AND THE ERD ELITISTS.
seriously Jim, using up threading to satisfy a programable math model
is self defeating.

fact: regardless of what your fears or opinions on this subject,
literally millions of wheels, over the course of 100 years, have been
built with this formula. *with complete success. *if you take nothing
else away from this conversation, let that fact be the one thing you can
accept.

for your future wheelbuilding endeavors, buy spokes with 3" of threading
and cut them to length yourself after building.

threading weakenss spokes?

datakoll wrote:
On Feb 5, 11:54�pm, jim beam wrote:
datakoll wrote:

an oversimplification form an engineer ?
I call for truth in spoke calc and the engineer cries out for
continued obfucstaion?
A graphic is an educational tool not oly for the consumer but MO and
LBS staff unable to enter data into spoke clcs and ship correct
lengths.
THE ERD DOESN'T WORK! THE ERD USES 90% of available spoke threading
just to satisfy GOD ERD AND THE ERD ELITISTS.
seriously Jim, using up threading to satisfy a programable math model
is self defeating.
fact: regardless of what your fears or opinions on this subject,
literally millions of wheels, over the course of 100 years, have been
built with this formula. �with complete success. �if you take nothing
else away from this conversation, let that fact be the one thing you can
accept.

for your future wheelbuilding endeavors, buy spokes with 3" of threading
and cut them to length yourself after building.

threading weakenss spokes?

why would it be weaker on the shaft than on the bit where the spoke
nipple is connected?

On Feb 6, 9:23Â*am, jim beam wrote:
datakoll wrote:
On Feb 5, 11:54�pm, jim beam wrote:
datakoll wrote:

an oversimplification form an engineer ?
I call for truth in spoke calc and the engineer cries out for
continued obfucstaion?
A graphic is an educational tool not oly for the consumer but MO and
LBS staff unable to enter data into spoke clcs and ship correct
lengths.
THE ERD DOESN'T WORK! THE ERD USES 90% of available spoke threading
just to satisfy GOD ERD AND THE ERD ELITISTS.
seriously Jim, using up threading to satisfy a programable math model
is self defeating.
fact: regardless of what your fears or opinions on this subject,
literally millions of wheels, over the course of 100 years, have been
built with this formula. �with complete success. �if you take nothing
else away from this conversation, let that fact be the one thing you can
accept.

for your future wheelbuilding endeavors, buy spokes with 3" of threading
and cut them to length yourself after building.

threading weakenss spokes?

why would it be weaker on the shaft than on the bit where the spoke
nipple is connected?- Hide quoted text -

- Show quoted text -

THIS IS WHERE THE DUCK FALLS FROM THE CEILING !