SPOKE LENGTH IN NIPPLE

Tosspot wrote:
jim beam wrote:
Tosspot wrote:
jim beam wrote:
Ben C wrote:
On 2008-02-02, jim beam wrote:
datakoll wrote:
A PHOTO OF a correct spoke length as the spoke end sits in the
mounted nipple. Notice the length is NOT at the ERD position.
then your problem has been confusion over what "erd" means. if
you use the rim manufacturer's erd data, and one of the spoke
calculators, the result will be perfect spoke length, as per
andrew's photo. every time.

OK in that case I'm still confused about ERD means.

"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.

Now I'm confused. I thought the ERD was measured from opposite nipple
seats in the rim and was \exactly\

"\" not "/"??? you've been playing with windoze _way_ too much my
friend.

SUSE 10.3, but anyhow it's not a discussion about OS's.

the number that determines spoke
length, eliminating the tyre seat nipple support difference. Thus
double wall, nipple seats et al, do not matter, the ERD is
the figure you need to know for spoke lengths.

"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?

My point was, surely it's defined?

by the rim, yes!


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.

this is a recurrent theme on r.b.t that i just don't understand!!! why
would anyone, ever, when given data by a manufacturer that has zero
influence on sales, especially when verified by a reliable r.b.t
contributor, ever get into issues of "trust" about that data??? i
simply can't comprehend that psychology.



I'm going to be dreaming spokes

snip for brevity

study this picture, courtesy of andrew muzi:

http://www.yellowjersey.org/photosfr...t/SPOKDEPT.JPG

manufacturer numbers give you this result. your interpretation of that
information is up to you.

datakoll wrote:
No Beam, the question is not does the math work out right, the
question is are the MO people capable of using spoke calc. And why
not?

unles you specify rim, hub and spoke crossing, the mo folks are simply
going to supply what you ask for. if you don't ask for the right length
because it's not calculated correctly, you'll not get the right product
delivered.



The results of this survey, limited as it is to the usual group of
cranks, screwballs, gyrogearloosi, and incompetents, head in the
direction of how is the ERD described in English.

The ERD is snot the spoke length. Spoke length is less than ERD. BUT!
spoke length is continuously described as ERD. That's the impression I
go away with.

it's simply calculation input, along with hub data and spoke crossing!!!
for any given erd, you'll get different spoke lengths for each of the
crossing options.



If you thread the nipple onto the spoke you will see the nipple seated
onto the rim at the (average) ERD has no more thread capacity.

no, average spoke length, not erd.


That was the question I asked. Where is the spoke end minus the ERD?
And the answer came back: The spoke end is the ERD. read it!

no, the erd /gives/ the spoke length when used in the calculation.



Like the ship is going down on defining the ERD for computer entry
data but then the ERD becomes the spoke length: forgetabboutit.

Someone go thru 10 spoke calcs reading if the calcs say what the ERD
is.

what's the purpose? the question is: what's the purpose of approaching
the ERD so closely like its a game of chicken (?!) getting the spoke
end right on top the ERD reduces the spokes chances for adjustment as
you just ran the spoke out of threads. So quack deduct 3mm from ERD.

you can. but rights to bleat about the result are thus automatically
forfeit.



I'm inclined to get a spoke length that touches the inside eyelet.
that's a good -3mm from ERD-and useful in my experience for HD touring
and long mileage wheel use.


post your rim info, hub info and desired crossing count. we'll then
calculate spoke length and you can go ahead and do your mo.

Frank Leake writes:

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?

My point was, surely it's defined? 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.

Try: http://www.damonrinard.com/SpocalcExpress.xls

You can change ERD and cross pattern until you find one that meets
your spoke length for your favorite spoke. The result is on the
screen as fast as you can hit ENTER. Try it, you'll like it. Of
course it solves for all the reasonable cross patterns at the same
time anyway.

Jobst Brandt

On Feb 2, 3:11*pm, Tosspot wrote:
jim beam wrote:
Tosspot wrote:
jim beam wrote:
Ben C wrote:
On 2008-02-02, jim beam wrote:
datakoll wrote:
A PHOTO OF a correct spoke length as the spoke end sits in the
mounted nipple. Notice the length is NOT at the ERD position.
then your problem has been confusion over what "erd" means. *if
you use the rim manufacturer's erd data, and one of the spoke
calculators, the result will be perfect spoke length, as per
andrew's photo. *every time.

OK in that case I'm still confused about ERD means.

"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.

Now I'm confused. *I thought the ERD was measured from opposite nipple
seats in the rim and was \exactly\

"\" not "/"??? *you've been playing with windoze _way_ too much my friend.

SUSE 10.3, but anyhow it's not a discussion about OS's.

the number that determines spoke
length, eliminating the tyre seat nipple support difference. *Thus
double wall, nipple seats et al, do not matter, the ERD is
the figure you need to know for spoke lengths.

"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?

My point was, surely it's defined? *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.

I'm going to be dreaming spokes

I check the ERDs for new model Mavic rims at several sites -- the
manufacturer, the usual on-line spoke calcs and in the groups just to
make sure. This is because I have gotten some wrong ERDs from the
Mavic site in years gone by. I trust the ERDs posted by Velocity, and
they have always yielded the right spoke lengths. Most of the spoke
calcs on line are pretty good and yield the same spoke length, but it
never hurts to use two or three of them just to cross check. -- Jay
Beattie.

On Feb 2, 7:24*pm, wrote:
Frank Leake writes:
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?
My point was, surely it's defined? *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.

Try: *http://www.damonrinard.com/SpocalcExpress.xls

You can change ERD and cross pattern until you find one that meets
your spoke length for your favorite spoke. *The result is on the
screen as fast as you can hit ENTER. *Try it, you'll like it. *Of
course it solves for all the reasonable cross patterns at the same
time anyway.

Jobst Brandt

http://www.machinehead-software.co.u..._explorer.html

also a possible software for figuring thru entering various known
quantities. I haven't tried it yet.

Jim Beam: the problem underlying the post question was an inexplicable
ongoing thickhgeadedness by MO software for supplying wrong spoke
lengths for double wall rims. A possible answer was the maybe ill
defined ERD application to real life non-LBS wheel building.

I was asking for where does the spoke end end in realtion to the rim
when the parts are on the dishing beam and built. I have a real
measure to the inside rim surface from hub hole and, have done this
before. BUTBUTBUT I wanted to refine the guesstimate. I have a vague
answre that vaguely agrees with my vague memory of before.

Practically tho, the nearness of LBS spoke ends spoken of here is
waaaayyyyy too close for my use. I'll go with ERD -3mm.

On Feb 2, 9:39*pm, datakoll wrote:
On Feb 2, 7:24*pm, wrote:





Frank Leake writes:
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?
My point was, surely it's defined? *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.

Try: *http://www.damonrinard.com/SpocalcExpress.xls

You can change ERD and cross pattern until you find one that meets
your spoke length for your favorite spoke. *The result is on the
screen as fast as you can hit ENTER. *Try it, you'll like it. *Of
course it solves for all the reasonable cross patterns at the same
time anyway.

Jobst Brandt

http://www.machinehead-software.co.u..._pattern_explo...

also a possible software for figuring thru entering various known
quantities. I haven't tried it yet.

Jim Beam: the problem underlying the post question was an inexplicable
ongoing thickhgeadedness by MO software for supplying wrong spoke
lengths for double wall rims. A possible answer was the maybe ill
defined ERD application to real life non-LBS wheel building.

I was asking for where does the spoke end end in realtion to the rim
when the parts are on the dishing beam and built. I have a real
measure to the inside rim surface from hub hole and, have done this
before. BUTBUTBUT I wanted to refine the guesstimate. I have a vague
answre that vaguely agrees with my vague memory of before.

Practically tho, the nearness of LBS spoke ends spoken of here is
waaaayyyyy too close for my use. I'll go with ERD -3mm.- Hide quoted text -

- Show quoted text -

ach did that again JB! (ERD/2)-3mm=spoke length

On 2008-02-02, Tosspot wrote:
jim beam wrote:
[...]
"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.

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.

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

jim beam wrote:
Tosspot wrote:
jim beam wrote:
Tosspot wrote:
jim beam wrote:
Ben C wrote:
On 2008-02-02, jim beam wrote:

datakoll wrote:
A PHOTO OF a correct spoke length as the spoke end sits
in the mounted nipple. Notice the length is NOT at the
ERD position.
then your problem has been confusion over what "erd"
means. if you use the rim manufacturer's erd data, and
one of the spoke calculators, the result will be perfect
spoke length, as per andrew's photo. every time.

OK in that case I'm still confused about ERD means.

"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.

Now I'm confused. I thought the ERD was measured from opposite
nipple seats in the rim and was \exactly\

"\" not "/"??? you've been playing with windoze _way_ too much
my friend.

SUSE 10.3, but anyhow it's not a discussion about OS's.

the number that determines spoke length, eliminating the tyre
seat nipple support difference. Thus double wall, nipple seats
et al, do not matter, the ERD is the figure you need to know
for spoke lengths.

"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?

My point was, surely it's defined?

by the rim, yes!

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.

this is a recurrent theme on r.b.t that i just don't understand!!!
why would anyone, ever, when given data by a manufacturer that has
zero influence on sales, especially when verified by a reliable r.b.t
contributor, ever get into issues of "trust" about that data??? i
simply can't comprehend that psychology.

I'm going to be dreaming spokes

snip for brevity

study this picture, courtesy of andrew muzi:

http://www.yellowjersey.org/photosfr...t/SPOKDEPT.JPG

manufacturer numbers give you this result. your interpretation of
that information is up to you.

Ah, I see the argument now. Right, I shall retire and watch the rest of
the thread.

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.

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