ERD...yet another thread

In article
<[email hidden]>,

datakoll said:

Michael Press said:

In article <[email hidden]>,

John Everett said:

Even though I've now ordered the spokes I was writing about when I
started the ERD thread, I still never received a clear answer to my
original question. Let me rephrase:

Quoted message said:

Should ERD actually be the diameter of the circle defined by the ends
of the spokes in the built wheel?

It is the diameter of the circle defined by the outermost
surface of the nipples. Many spoke calculators aim to get
the end of the spoke to or almost to that circle, even taking
into account the elastic elongation of the spoke.

Quoted message said:

If so, should the end of the spokes
theoretically be even with the top of the nipple, or buried somewhere
inside the nipple? If buried, should they be even with the outside
surface of the rim holes, or even with the bottom of the screwdriver
slot?

Quoted message said:

Note that we're talking about millimeter differences here, which
strikes me as a bit like discussing the number of angels the can dance
on the head of a pin.  ;-)

Do not ignore small corrections. They can add up
and leave you with a situation that will take
you far longer to remedy than the initial time
investment in getting it right. People who know,
know what can be ignored because the have calculated
the error bounds far closer than one millimeter.

Quoted message said:

I've re-rimmed wheels with rims that were
5mm larger in published ERD than the originals without problems. Makes
me wonder how many nipple threads actually need to be engaged to build
a safe wheel.

Asking me? All of them.

Quoted message said:

I'm guessing from Jobst's response in my OP's thread that ERD is
precisely defined in "The Bicycle Wheel", but I've managed to build a
number of wheels without ever reading it.

Are you asking for our advice?

See here's another one.
YO MATH WHIZ ? if ERD is a diameter then why are rear spokes in two
lengths ?

Is this a trick question?
The rim is not centered at the mid-point of the two hub flanges.
ERD is measured in the mid-plane of the rim, not along the spokes.

Here is one for you. How is it that anything can float in water?

--
Michael Press

sez Press:
'ERD is measured in the mid-plane of the rim, not along the spokes.'

if ERD is measured thru the rim's mid-plane then why in explketive
deleted would ERD represent spoke length where spokes do not run thru
the mid plane of the rim???

datakoll aka Gene Daniels said:

See here's another one.
YO MATH WHIZ ? if ERD is a diameter then why are rear spokes in two
lengths ?

On a dish-less rear wheel, the spokes can all be the same length.

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

Mike,

the subject begs refocusing.

Brandt published a book giving the public access to bicycle wheel
engineering. A significant contribution is the math constant ERD,
standardizing an approach to measuring spoke length.

But Brandt then linked ERD, a number, to Brandt's OPINION on spoke
lengths TO WIT: spokes should run to the top of the nipple head.

Brandt, in giving his incorrect opinion on spoke length forever linked
ERD to an incorrect opinion, reducing ERD's math purity to an
confusing obfuscation. Or conversely gave an incorrect opinion math
certainty.

If you read thru the posts herein, that is what you will read: the
effect of Brandt mixing opinion and math certainty. I wasn't seeking
that production but this is the discussion's result if not
clarification.
Surly, rider-mechanics who rattleon about spoke measurements lying in
the diameter are beyong immediate redemption.

On Mar 12, 12:58 am, Tom Sherman <[email hidden]>

Quoted message said:

datakoll aka Gene Daniels said:

See here's another one.
YO MATH WHIZ ? if ERD is a diameter then why are rear spokes in two
lengths ?

On a dish-less rear wheel, the spokes can all be the same length.

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

not if they're using spoke clac

John Everett said:

Even though I've now ordered the spokes I was writing about when I
started the ERD thread, I still never received a clear answer to my
original question. Let me rephrase:

Should ERD actually be the diameter of the circle defined by the ends
of the spokes in the built wheel? If so, should the end of the spokes
theoretically be even with the top of the nipple, or buried somewhere
inside the nipple? If buried, should they be even with the outside
surface of the rim holes, or even with the bottom of the screwdriver
slot?

Note that we're talking about millimeter differences here, which
strikes me as a bit like discussing the number of angels the can dance
on the head of a pin.  ;-)  I've re-rimmed wheels with rims that were
5mm larger in published ERD than the originals without problems. Makes
me wonder how many nipple threads actually need to be engaged to build
a safe wheel.

I'm guessing from Jobst's response in my OP's thread that ERD is
precisely defined in "The Bicycle Wheel", but I've managed to build a
number of wheels without ever reading it.

--
jeverett3<AT>sbcglobal<DOT>net      (John V. Everett)

It doesn't matter how you define it, as long as you're consistant.
Since it's called the effective RIM diameter, I use
the diameter measured at the nipple seat. Different spoke calculating
formulas give different answers but they are repeatable, eg, the
wheelsmith formula has the spokes end at about the same diameter,
which I consider too short, so I simply add 2-3mm to the result. The
system is reliable, and likewise however you choose to define ERD &
whichever formula you apply, you'll get consistent results if you're
consistent in your methods.

As to the proper height of a spoke in the nipple. I've seen debate on
this for years, everyone has an opinion, here's how I arrived at
mine. First considering that spokes & nipples are threaded
fasteners,I'll treat them as such. The nipple is basically a nut (the
head) with an extension to allow it to be turned from below, (towards
the hub). Given that in both brass & alloy nipples there isn't enough
section for the extension to have the same structural strength as the
spoke, I only consider spoke engagement into the head. I then apply
the standard fastener industry guideline of 1 diameter of the screw
(spoke) as the minimum to achieve full strength. Long story short,
spokes should come at least 2mm past the rim into the head of the
nipple, or about to the bottom of the slot. That's a minimum so err up
1mm for a workable tolerance. Optimum final spoke length - between
the slot depth & top of the nipple. Any less & you lose strength, any
more is extra weight, (or you run out of thread) fb

datakoll said:

datakoll said:

Michael Press said:

In article <[email hidden]>,
�John Everett <[email hidden]> wrote:
> Even though I've now ordered the spokes I was writing about when I
> started the ERD thread, I still never received a clear answer to my
> original question. Let me rephrase:
> Should ERD actually be the diameter of the circle defined by the ends
> of the spokes in the built wheel?
It is the diameter of the circle defined by the outermost
surface of the nipples. Many spoke calculators aim to get
the end of the spoke to or almost to that circle, even taking
into account the elastic elongation of the spoke.
> If so, should the end of the spokes
> theoretically be even with the top of the nipple, or buried somewhere
> inside the nipple? If buried, should they be even with the outside
> surface of the rim holes, or even with the bottom of the screwdriver
> slot?
> Note that we're talking about millimeter differences here, which
> strikes me as a bit like discussing the number of angels the can dance
> on the head of a pin. �;-) �
Do not ignore small corrections. They can add up
and leave you with a situation that will take
you far longer to remedy than the initial time
investment in getting it right. People who know,
know what can be ignored because the have calculated
the error bounds far closer than one millimeter.
> I've re-rimmed wheels with rims that were
> 5mm larger in published ERD than the originals without problems. Makes
> me wonder how many nipple threads actually need to be engaged to build
> a safe wheel.
Asking me? All of them.
> I'm guessing from Jobst's response in my OP's thread that ERD is
> precisely defined in "The Bicycle Wheel", but I've managed to build a
> number of wheels without ever reading it.
Are you asking for our advice?
--
Michael Press

See here's another one.
YO MATH WHIZ ? if ERD is a diameter then why are rear spokes in two
lengths ?- Hide quoted text -

- Show quoted text -

again... ERD is a math constant

no, it's a variable, not a constant. _one_ of the variables used in the
calculation. different rims have different erd's.

Quoted message said:

used to derive spoke lengths. ERD
exists as a measurment, a number not as a spoke length. NOT AS A SPOKE
LENGTH.

of course not. one would have to be grasping a very wrong-ended stick
to think so.

Quoted message said:

butbutbut for some inexplicable reason, Rinard and Brandt go on to
confuse c-o-n-f-u-s-e ERD with spoke length.

no they don't.

Quoted message said:

and promulgulate the confucion with extraordinary success from the
looks of it.

pawsibley other spoke calcs do the same, i dunno. By the time i get
thru one wheel I'm thru for the year but this time...I'm too busy. the
*&*((( with it.

and dished rears use different spoke lengths on each side because of
different geometry each side of the hub. trigonometry is your friend.

jim beam said:

datakoll said:

datakoll said:

On Mar 12, 12:08�am, Michael Press <[email hidden]> wrote:

Quoted message said:

Quoted message said:

> In article <[email hidden]>,
> �John Everett <[email hidden]> wrote:
>> Even though I've now ordered the spokes I was writing about when I
>> started the ERD thread, I still never received a clear answer to my
>> original question. Let me rephrase:
>> Should ERD actually be the diameter of the circle defined by the ends
>> of the spokes in the built wheel?
> It is the diameter of the circle defined by the outermost
> surface of the nipples. Many spoke calculators aim to get
> the end of the spoke to or almost to that circle, even taking
> into account the elastic elongation of the spoke.
>> If so, should the end of the spokes
>> theoretically be even with the top of the nipple, or buried somewhere
>> inside the nipple? If buried, should they be even with the outside
>> surface of the rim holes, or even with the bottom of the screwdriver
>> slot?
>> Note that we're talking about millimeter differences here, which
>> strikes me as a bit like discussing the number of angels the can dance
>> on the head of a pin. �;-) �
> Do not ignore small corrections. They can add up
> and leave you with a situation that will take
> you far longer to remedy than the initial time
> investment in getting it right. People who know,
> know what can be ignored because the have calculated
> the error bounds far closer than one millimeter.
>> I've re-rimmed wheels with rims that were
>> 5mm larger in published ERD than the originals without problems. Makes
>> me wonder how many nipple threads actually need to be engaged to build
>> a safe wheel.
> Asking me? All of them.
>> I'm guessing from Jobst's response in my OP's thread that ERD is
>> precisely defined in "The Bicycle Wheel", but I've managed to build a
>> number of wheels without ever reading it.
> Are you asking for our advice?
> --
> Michael Press
See here's another one.
YO MATH WHIZ ? if ERD is a diameter then why are rear spokes in two
lengths ?- Hide quoted text -

Quoted message said:

Quoted message said:

- Show quoted text -

Quoted message said:

again...   ERD is a math constant

no, it's a variable, not a constant.  _one_ of the variables used in the
calculation.  different rims have different erd's.

Quoted message said:

used to derive spoke lengths. ERD
exists as a measurment, a number not as a spoke length. NOT AS A SPOKE
LENGTH.

of course not.  one would have to be grasping a very wrong-ended stick
to think so.

Quoted message said:

butbutbut for some inexplicable reason, Rinard and Brandt go on to
confuse c-o-n-f-u-s-e ERD with spoke length.

no they don't.

Quoted message said:

and promulgulate the confucion with extraordinary success from the
looks of it.

Quoted message said:

pawsibley other spoke calcs do the same, i dunno. By the time i get
thru one wheel I'm thru for the year but this time...I'm too busy. the
*&*((( with it.

and dished rears use different spoke lengths on each side because of
different geometry each side of the hub.  trigonometry is your friend..- Hide quoted text -

- Show quoted text -

BEAM SUPPORTS BRANDT now we're getting somewhere...

OK. ERD is a variable constant? Brandt's definition for ERD was meant
to hold calculations to one standard, Brandt's definition, for all
rims. Can we go on?

A spoke calc user feeds ERD and hub sizes into the software and out
poops spoke lengths
but ERD gives spoke lengths running from hub hole to top of the nipple
head.

Spoke lengths running from hub hole to top of the nipple head are an
opinion producing incorrect spoke lengths, not a standard like ERD
producing correct spoke lengths.

That's my conclusion, not to hassle Jobst Brandt but an obvious point
run aground on looking for reasons why posters ask WTF is this about
after using spike clac for mail odoring all wheel parts previously
unseen and unmeasured.

'oldbike' offers an 'industry standard' for full thread holding power?
I haven't read that material for several years so...
Stating one diameter of the screw into female threading gives as much
grip as anything to follow.
I get an immediate feel here that IS are suggesting diminishing
returns
and that 'oldbike' immediately misuses the standard-continuing the
humor.

As for IS. Weall arrive at the nipple with a spoke(s) too short,
threading spoke into nipple with a few oaths. IS seems correct. One
spoke OD in and itsnot likely to pull out. That is surly not threaded
to the top of the nipple head. I had a 10 year old too short spoke
pull out from maybe 2.5 diameters into the nipple. That ancient spoke
snapped not pulled out of the threads.

datakoll said:

Mike,

the subject begs refocusing.

Brandt published a book giving the public access to bicycle wheel
engineering. A significant contribution is the math constant ERD,
standardizing an approach to measuring spoke length.

But Brandt then linked ERD, a number, to Brandt's OPINION on spoke
lengths TO WIT: spokes should run to the top of the nipple head.

Brandt, in giving his incorrect opinion on spoke length forever linked
ERD to an incorrect opinion, reducing ERD's math purity to an
confusing obfuscation. Or conversely gave an incorrect opinion math
certainty.

If you read thru the posts herein, that is what you will read: the
effect of Brandt mixing opinion and math certainty. I wasn't seeking
that production but this is the discussion's result if not
clarification.
Surly, rider-mechanics who rattleon about spoke measurements lying in
the diameter are beyong immediate redemption.

I'll give Gene one thing...he's doggedly obstinate, even when he's
wrong.

ERD is Effective Rim Diameter, and IS NOT A MATH CONSTANT!!! It's a
measurable dimension associated with each rim.

I just went around the house and garage and measured the outside
diameter of a bunch of 700C rims. Not surprisingly they all measured
the same, 634mm (at least with my wooden yardstick). Using the
"non-business" end of my dial caliper it's really easy to measure
depths. Measuring an Alex DM18, the depth from the rim edge to the top
of a spoke hole grommet is 13mm, thus one could call the ERD of this
rim 608mm (634 minus twice 13). The Alex web site lists it as 606.4mm.

If one wanted to plug either of these figures into spocalc one would
get spoke lengths which would build perfectly serviceable wheels. You
could even add a couple of millimeters to ERD and wind up with spokes
that would theoretically come close to the tops of the nipples.

Last evening I drove over to Dave Ornee's house and picked up a set of
Sapim Race spokes for the wheel build that caused me to start these
ERD threads. We had a brief discussion about wheel building and we
both pretty much agree that there's a fairly wide range of spoke
penetrations into the nipples that will result in successful wheels.
The range is probably anywhere from 5 turns onto the spoke threads to
where the spoke end protrudes from the nipple head, consistant with no
possibility of tube puncturing and not jamming the nipple too far onto
the non-threaded portion of the spoke.

Anyway I now have my spokes. With this my participation in these
threads ends.

--
jeverett3<AT>sbcglobal<DOT>net (John V. Everett)

Everett, ERD is a definiton designed to maintain a constant universal
math approach to the trig used to spec spoke lengths

Your objection is semantic. My use of constant was meant to maintain
brevity, eliminate confusion.

JB's opinion is not semantic confusion or is it?

I am not wrong.

The tide is out. You may go.

In article <[email hidden]>,

John Everett said:

I just went around the house and garage and measured the outside
diameter of a bunch of 700C rims. Not surprisingly they all measured
the same, 634mm (at least with my wooden yardstick). Using the
"non-business" end of my dial caliper it's really easy to measure
depths. Measuring an Alex DM18, the depth from the rim edge to the top
of a spoke hole grommet is 13mm, thus one could call the ERD of this
rim 608mm (634 minus twice 13). The Alex web site lists it as 606.4mm.

It helps to have a single definition of ERD. ERD was never
heard of until it was defined in a book on wheel building.
What you measured is not ERD by the first definition. ERD is
measured to the top of a nipple seated in the rim. You
measured to the seat, and that is not the same thing.

Spoke length calculators that use a different definition of
ERD and manufacturers that use a different definition sow
confusion. The confusion is more harmful than varying definitions
of seat tube length and top tube length. The usual variant
definition of ERD will not by itself cause spokes to be
unusable if the original ERD is measured by the user; but
combined with variations in other measurements or with an
attempt to use spokes a little longer than the output of the
spoke calculator will end in tears. Another variation among
spoke calculators is where they mean for the end of the spoke
to be relative to the top of the nipple. Another variation
is allowance for elastic spoke elongation. These variations
can add up to give a calculated spoke length that is unworkable.

--
Michael Press

In article
<[email hidden]>,

datakoll said:

sez Press:
'ERD is measured in the mid-plane of the rim, not along the spokes.'

if ERD is measured thru the rim's mid-plane then why in explketive
deleted would ERD represent spoke length where spokes do not run thru
the mid plane of the rim???

ERD is not spoke length. It is a dimension among others
used to calculate spoke length.

--
Michael Press

In article
<[email hidden]>,

datakoll said:

Mike,

the subject begs refocusing.

Brandt published a book giving the public access to bicycle wheel
engineering. A significant contribution is the math constant ERD,
standardizing an approach to measuring spoke length.

But Brandt then linked ERD, a number, to Brandt's OPINION on spoke
lengths TO WIT: spokes should run to the top of the nipple head.

Brandt, in giving his incorrect opinion on spoke length forever linked
ERD to an incorrect opinion, reducing ERD's math purity to an
confusing obfuscation. Or conversely gave an incorrect opinion math
certainty.

If you read thru the posts herein, that is what you will read: the
effect of Brandt mixing opinion and math certainty. I wasn't seeking
that production but this is the discussion's result if not
clarification.
Surly, rider-mechanics who rattleon about spoke measurements lying in
the diameter are beyong immediate redemption.

ERD must be defined precisely. Likewise the location of
the end of the calculated spoke length must be defined
precisely. Only then can we depend on the calculated
spoke length to be suitable for our purposes. You are
at liberty to do as you please. You are at liberty to
attack a particular definition of ERD and choice of
spoke end position. You are at liberty to construct
your own edifice to predict the length of the spokes to
use with your rim and hub.

--
Michael Press

Michael Press said:

In article
<[email hidden]>,

datakoll said:

Mike,

Quoted message said:

the subject begs refocusing.

Quoted message said:

Brandt published a book giving the public access to bicycle wheel
engineering. A significant contribution is the math constant ERD,
standardizing an approach to measuring spoke length.

Quoted message said:

But Brandt then linked ERD, a number, to Brandt's OPINION on spoke
lengths TO WIT: spokes should run to the top of the nipple head.

Quoted message said:

Brandt, in giving his incorrect opinion on spoke length forever linked
ERD to an incorrect opinion, reducing ERD's math purity to an
confusing obfuscation. Or conversely gave an incorrect opinion math
certainty.

Quoted message said:

If you read thru the posts herein, that is what you will read: the
effect of Brandt mixing opinion and math certainty. I wasn't seeking
that production but this is the discussion's result if not
clarification.
Surly, rider-mechanics who rattleon about spoke measurements lying in
the diameter are beyong immediate redemption.

ERD must be defined precisely. Likewise the location of
the end of the calculated spoke length must be defined
precisely.  Only then can we depend on the calculated
spoke length to be suitable for our purposes. You are
at liberty to do as you please. You are at liberty to
attack a particular definition of ERD and choice of
spoke end position. You are at liberty to construct
your own edifice to predict the length of the spokes to
use with your rim and hub.

--
Michael Press- Hide quoted text -

- Show quoted text -

Mike Rules,

right. I agree more or less.

Rinard/Brandt/Brown/harris is a preeminent spoke calc.
The RBRh calc produces "wrong" spoke lengths from an outdated approach
to the CLASS ERD where point B, the nipple heads., are wrongly defined
as WHERE THE SPOKE ENDS SHOULD BE.
Jesus.
A simple instruction at RBRh for examining real time spoke threading
before choosing the nipple head as point B is what I was lobbying for.

Itsnot a big deal really, a simple instruction is all that's
YYYOOOOOOOOHOOOOOOOO! called for...

Now I did it, again with correction in caps, not changing ERD but
suggesting an after calculation deduction may be in order after
examination of nipple and spoke in real time

Quoted message said:

Mike Rules,

right. I agree more or less.

Rinard/Brandt/Brown/harris is a preeminent spoke calc.
The RBRh calc produces "wrong" spoke lengths from an outdated approach
to the CLASS ERD where point B, the nipple heads., are wrongly defined
as WHERE THE SPOKE ENDS SHOULD BE.
Jesus.
A simple instruction at RBRh for examining real time spoke threading
before choosing the nipple head as point B as WHERE THE SPOKE ENDS SHOULD BE. is what I was lobbying for.

Itsnot a big deal really, a simple instruction is all that's
YYYOOOOOOOOHOOOOOOOO! called for...- Hide quoted text -

- Show quoted text -

Quoted message said:

Quoted message said:

John Everett said:

Even though I've now ordered the spokes I was writing about when I
started the ERD thread, I still never received a clear answer to my
original question. Let me rephrase:
Should ERD actually be the diameter of the circle defined by the ends
of the spokes in the built wheel?

Quoted message said:

Michael Press said:

It is the diameter of the circle defined by the outermost
surface of the nipples. Many spoke calculators aim to get
the end of the spoke to or almost to that circle, even taking
into account the elastic elongation of the spoke.

Quoted message said:

Quoted message said:

John Everett said:

If so, should the end of the spokes
theoretically be even with the top of the nipple, or buried somewhere
inside the nipple? If buried, should they be even with the outside
surface of the rim holes, or even with the bottom of the screwdriver
slot?
Note that we're talking about millimeter differences here, which
strikes me as a bit like discussing the number of angels the can dance
on the head of a pin. ;-)

Quoted message said:

Michael Press said:

Do not ignore small corrections. They can add up
and leave you with a situation that will take
you far longer to remedy than the initial time
investment in getting it right. People who know,
know what can be ignored because the have calculated
the error bounds far closer than one millimeter.

Quoted message said:

Quoted message said:

John Everett said:

I've re-rimmed wheels with rims that were
5mm larger in published ERD than the originals without problems. Makes
me wonder how many nipple threads actually need to be engaged to build
a safe wheel.

Quoted message said:

Michael Press said:

Asking me? All of them.

Quoted message said:

Quoted message said:

John Everett said:

I'm guessing from Jobst's response in my OP's thread that ERD is
precisely defined in "The Bicycle Wheel", but I've managed to build a
number of wheels without ever reading it.

Quoted message said:

Michael Press said:

Are you asking for our advice?

datakoll said:

See here's another one.
YO MATH WHIZ ? if ERD is a diameter then why are rear spokes in two
lengths ?

Uh, because they are the hypotenuses of two triangles to the same (ERD)
altitude with different (flange offset) bases.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

datakoll said:

sez Press:
'ERD is measured in the mid-plane of the rim, not along the spokes.'

Quoted message said:

if ERD is measured thru the rim's mid-plane then why in explketive
deleted would ERD represent spoke length where spokes do not run thru
the mid plane of the rim???

See if this helps:
http://www.grc.nasa.gov/WWW/K-12/airplane/pythag.html

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

what's REALLY happening here is correct measurements in all areas
asked for are then distorted by Brandt's authority ndefining ERD as
spokes end at spoke heads.
ERD then determines spoke length on Brandt's authority.
For the unaware, novice, people in a rush...mail odor personnel... DIY
types not reading RBT...

John Everett said:

[...]
Anyway I now have my spokes. With this my participation in these
threads ends.

Well spoken.

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

On Mar 12, 9:24 pm, Tom Sherman <[email hidden]>

Quoted message said:

John Everett said:

[...]
Anyway I now have my spokes. With this my participation in these
threads ends.

Well spoken.

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

my day was ruined