ERD...yet another thread
John Everett
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)
datakoll
.ERD is the standard length you use to
DEDUCT from to order spokes
measuring for double walls takes NIQ+10 where we arrive at 0
insert spoke into rim, magic tape insertion at rim inside entry hole
for nipple head reach, then for slot base reach, then for 1.5mm short
of slot base reach.
OR tape spoke shaft when spoke reachs inside rim eyelet (the grommet
reinforcement)
WRITE THE NUMBERS DOWN WITH ASSCOCIATED DIAGRAM IN YOUR LOG BOOK.
then insert spoke into nipple to threading: tape insertion on spoke.
measure the short end.
then thread spoke onto nipple until spoke arrives at slot base. tape
spoke shaft and measure short end.
WRITE THE NUMBERS DOWN IN YOUR LOG BOOK.
you now have a spoke length table. Use the table for tilting at ERD.
841
ERD is snot spoke length, spoke length is AESL. Rinard and Brandt,
obviously highly intelligent people continue chanting ERD like mary
had a little lamb is spoke length until people of normal
intelligence
believe that, to their error and consternation.
Clearing the problem off the boards using magic tape and AESL is
similar to Gates' ascesnion to world's second richest man, having
soooooo much money he gave it to Africans soooo we can have more
Africans.
MP,
gnaw. you missed the point. Brandt sez ERD is his idea. ERD
establishes ONE MEASUREMENT STANDRAD for one wheel combination, not 4
standradrs for one wheel combination.
BUTBUTBUT ERD is snot AESL. AESL is the small range of engaged
threading used for ordering spokes and building the wheel. AESL=ERD-
SDR (standard deduction range)
ERD is software's spoke calc standard hypotenuse length as a math
constant. (maybe also a disease)
Its snot the length you use to order spokes. ERD is the standard
length you use to
DEDUCT from to order spokes
Yeah. the dishing beam is essential and a basic wheel building tool.
Insert spokes, seat, gives correct dish. A red oak or better beam
should lean in every shop's corner.
almost. ERD is an hypotenuse not a diameter. That's why we're
suffering thru the grinding interface of language and math here thru
god software and priests.
try using magic tape for defining threading position inside the
nipple. The threading engagment of spoke and nipple related to actual
effective spoke length (AESL) NOT ERD is the measurement we're after
here.
That's a refinment of what you wrote. right?
the mezzanine is on your left
John Everett
<data...@yahoo.com> wrote:
>
>
>.ERD is the standard length you use to
>DEDUCT from to order spokes
Sounds basic enough, but DEDUCT implies simple subtraction. It's not
that easy. Here's the formula I used in a spreadsheet I put together
many, many years ago to calculate spoke lengths:
=D11/2+0.998*(SQRT(D6^2/4+D7^2/4-D6*D7/2*COS(PI()*4*D9/D8)+D10^2))
where: D6 is what we refer to as ERD. I just noticed that in the
spreadsheet I refer to D6 as "Diameter of rim at spoke holes". Clearly
I put the spreadsheet together before I'd ever heard the term ERD.
BTW, my original spoke length spreadsheet was done so long ago I used
Lotus 123. The above is from an Excel conversion.
YABTW, if anyone wants a copy of my simple spreadsheet send an email
and I'll forward it. It's not as spiffy as spocalc and you have to
provide all the measurements yourself, but it gets spokes of the
correct length. :-)
Art Harris
>
> Should ERD actually be the diameter of the circle defined by the ends
> of the spokes in the built wheel?
>
Yes.
> If so, should the end of the spokes
> theoretically be even with the top of the nipple, or buried somewhere
> inside the nipple?
>
Ideally, spoke ends should be even with the top of the nipple.
You should try to get the spoke length right to within a mm.
Art Harris
datakoll
diameter of a circle?
John is pulling our leg on his math trip.
take the rim, the spoke, and the nipple - any long enough to go thru
the rim with rim and hub mounted ona dishing beam
and fool with it as in the above instructions.
ERD-Standard Deduction (the threading arrangement the builder will
work out to his satisfaction NOT RINARD or JB or EUCLID or GODEL) =
AESL - useable spoke length
ERD isnot useable spoke length
Andre Jute
ordered from DT Swiss a thousand rims, with enough spokes and tools
and accessories to build a thousand wheels. Do you think that with
your instructions I might manage to build one wheel that rolls?
Whether the mezzanine is on your right or on your left depends on the
direction from which you arrive. You can't get there from here.
Yours admiringly,
A humble aspirant Obfuskator
datakoll
>
> - Show quoted text -
built muh first wheel without instructions.
then with Brwon's instructions but spoke clac lengths' I nevah bilt
another right off again
from which frustration led to the current hoooha.
IF the beam is built, and the builder fiddles with threading,
recording his measurement's in a retrievable fashion, tries
experimental spokes on the beam AND consults RINARD - DT et al then
urine.
As you can see, the approach to Rinard is incomplete. Addition of HOW
TO MEASURE articles obviously doesnot help overcome the problem JB-
Rinard et al brought on us: that ERD is spoke length when ERD is a
math constant for spoke length(s). An odd innocent twist to a semantic
pron]bl;em? Not with the intelligence carrying the obfuscation.
Ben C
> 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?
Yes, that is exactly what it is, qua an input to the calculators.
In other words, suppose you want opposite spoke ends 595mm apart. Then
put 595mm in the formula, and you should get a spoke length that will
give you opposing spoke ends 595mm apart in the finished 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?
That's a matter of personal preference. I think datakoll prefers his
coming up as far as about the bottom of the screwdriver slot.
That's pretty much ideal in terms of the final position, but others may
prefer the spokes 1mm or 1.5mm longer than that because it may make
lacing easier-- more threads to grab hold of while the spokes are all
still very loose.
> 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. ;-)
Mavic for example don't quote an ERD, but a spoke support diameter. This
is the distance between nipple seats, and is therefore about 3mm shorter
than the ERD as defined by Brandt. But it's a perfectly good spoke
length to just use without adding 3mm.
If you're like datakoll and like your spokes a bit shorter, you might be
tempted to subtract 3mm from a quoted ERD to get the spoke support
diameter and use that so your spokes come up to the bottom of the nipple
heads.
The problem is can you be sure it's really an ERD in the strict
Brandtian sense and not a spoke support diameter? Not everyone is so
careful with these terms. As far as many people are concerned, there is
just the length you want: it's just a number, and what you want to call
it ("ERD", "spoke support diameter", etc.) is mere technobabble. It
doesn't always occur to the man in the LBS to wonder whether sir would
like his spokes to run to the bottom or to the top of the nipples.
That's why if you find a number printed somewhere just go with that--
the worst that can happen is your spokes are a harmless 3mm from your
personal preference. But if you add 3mm or subtract 3mm thinking you
know what you're doing, but jump the wrong way, you could be 6mm out,
which could be a bit too far.
> 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 should think certainly not 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.
He defines it as the length to get the spoke to the top of the nipple.
Ben C
> ART really, is ERD a diameter? spoke clac is used to arrive at the
> diameter of a circle?
No, spoke clac gives you the spoke length _from_ the diameter of a
circle. ERD is an input, and is something you can reasonably easily
measure with a piece of string.
The only reason for deducting a bit from ERD is because you like your
spokes a bit shorter.
datakoll
>
> - Show quoted text -
OK one more time for the slow
ERD is a math constant ignoring the varieties of human and non-human
experience with spoke nipples and spoke threads. ERD is the real time
hypotenuse of a theorectic circle described by a bicycle wheel. ERD is
the measurement from a cone's point to the cone's base minus the cone
decribed by a cone who who whose base is formed by spoke hub holes and
following the path of the larger cone, the distance to a theorectic
point above axle center.
ERD as a real time measurement fails BECAUSE spokes and nipples do
not or should not thread to the nipple head.
A Muzi
datakoll wrote:
> built muh first wheel without instructions.
> then with Brwon's instructions but spoke clac lengths' I nevah bilt
> another right off again
> from which frustration led to the current hoooha.
> IF the beam is built, and the builder fiddles with threading,
> recording his measurement's in a retrievable fashion, tries
> experimental spokes on the beam AND consults RINARD - DT et al then
> urine.
> As you can see, the approach to Rinard is incomplete. Addition of HOW
> TO MEASURE articles obviously doesnot help overcome the problem JB-
> Rinard et al brought on us: that ERD is spoke length when ERD is a
> math constant for spoke length(s). An odd innocent twist to a semantic
> pron]bl;em? Not with the intelligence carrying the obfuscation.
We calc and build wheels all day long and, believe me, we just cannot
afford to be wrong about a spoke length. Whatever frustration you have
would be shared _plus_ we'd lose the time of a wheel build. And time, as
you know, is money.
For a wheelbuilder doing several pairs per day of various road and track
wheels, a standard software tool such as "spocalc2" and a set of rim
measuring gauges[1] are all that's needed. Spoke length turns out, in
real life, to be a trivial and quick calculation.
For the dedicated home builder, I am sympathetic to the various
impediments to selecting a spoke length. Good failsafe methods include:
*Buying spokes when you buy the rims, making the vendor responsible
*Asking the spoke vendor to do a calculation for you
*Asking any of the many wheelbuilders who frequent here to calc for you.
*making a set of rim gauges, measuring your hubs and using spocalc2.
An alternate method is to nearly build with the wrong length spokes and
interpolate which, it seems, may work just fine for you now!
I hesitate to mention (but I will, here goes!) that various
wheelbuilders have distinct preferences as to whether the spoke ends at
the inside edge of the rim, at the outer end of the nipple or somewhere
in between. Functionally, across that 2mm range, it matters not; any are
just fine.
[1] two 350mm welding rods each with a 4mm washer brazed flush at the end.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
datakoll
> datakoll wrote:
>
> -snip ERD redux-
>
> > urine-
> > As you can see, the approach to Rinard is incomplete. Addition of HOW
> > TO MEASURE articles obviously doesnot help overcome the problem JB-
> > Rinard et al brought on us: that ERD is spoke length when ERD is a
> > math constant for spoke length(s). An odd innocent twist to a semantic
> > pron]bl;em? Not with the intelligence carrying the obfuscation.
>
> afford to be wrong about a spoke length. Whatever frustration you have
> would be shared _plus_ we'd lose the time of a wheel build. And time, as
> you know, is money.
>
> For a wheelbuilder doing several pairs per day of various road and track
> wheels, a standard software tool such as "spocalc2" and a set of rim
> measuring gauges[1] are all that's needed. Spoke length turns out, in
> real life, to be a trivial and quick calculation.
>
> For the dedicated home builder, I am sympathetic to the various
> impediments to selecting a spoke length. Good failsafe methods include:
> *Buying spokes when you buy the rims, making the vendor responsible
> *Asking the spoke vendor to do a calculation for you
> *Asking any of the many wheelbuilders who frequent here to calc for you.
> *making a set of rim gauges, measuring your hubs and using spocalc2.
>
> An alternate method is to nearly build with the wrong length spokes and
> interpolate which, it seems, may work just fine for you now!
>
> I hesitate to mention (but I will, here goes!) that various
> wheelbuilders have distinct preferences as to whether the spoke ends at
> the inside edge of the rim, at the outer end of the nipple or somewhere
> in between. Functionally, across that 2mm range, it matters not; any are
> just fine.
>
Andy Muzi perspective as LBS owner and my perspective as Group Two
amatuer wheel builder are disimilar. Muzi knows what he's doing and
the wheels are his repsonsibility but the wheels are not his wheels.
when wheels leave Yellow Jersey, the wheels are the responsibility of
the owner.
I don't know what I'm doing and the wheels are my wheels come hell or
high water.
There are more of me than there are of Muzi but Muzi is responsible
for more wheels-which is a good deal for the planet.
Andrew's solution to spoke length IS NOT ERD. Andy's photo for the
first run in over ERD clear;y showed a spoke short of the nipples slot
base-waaaaaaaay down the road from the nipple's head.
My deal here is snot selling wheels to the non wheel building publick.
My deal is spreading some education on ERD thru RBT after an expert
(which is another difference, I gotta deal with THE EXPERT and Muzi is
the expert) sent the Nth batch of incorrect spoke lengths then swore
up and down that Rinard and Godel vouched his lengths were the right
lengths.
I recommended that Rinard change his evil ways avoiding further
inconvenience for the novice wheel builder before we get out there and
burnum out.
jim beam
what he said.
jim beam
yet again dude, post your rim and hub data so we can work it out for
you. if you don't want to do it yourself. relying on a shop to sell
you what they happen to have isn't always going to give you what you
actually want.
datakoll
chew gum and walk.
A bicycle wheel is of two parts. Two cones mated at the base, aka RIM,
and connected at the points or apex (?) by an axle.
THERE IS NO DIAMETER on a bicycle wheel.
THERE IS NO ERD. ERD EXISTS ONLY IN SPOKE CALC SOFTWARE
THIS IS THE PROBLEM.
Its like the Sienfeld Conundrum: if you measure ERD it exists but when
you stop measuring ERD it does not exist,
OBVIOULSY.
you see Beam ? That's the ongoing controverys raised here not the
fact that the MO spokes were again the wrong lengths. people are
wandering the landscape muttering about ERD and getting incorrect
spoke lengths caws they are misled by spoke calcs into believing the
ERD is a spoke length when itsnot a spoke length. Damn thing doesn;t
exists for &^^6*FRT!!
Michael Press
John Everett <jeve...@sbcglobal.DEFEAT.UCE.BOTS.net> 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
Michael Press
A Muzi <a...@yellowjersey.org> wrote:
> For a wheelbuilder doing several pairs per day of various road and track
> wheels, a standard software tool such as "spocalc2" and a set of rim
> measuring gauges[1] are all that's needed.
[...]
> [1] two 350mm welding rods each with a 2mm washer brazed flush at the end.
Neat.
--
Michael Press
datakoll
> In article <haadt3h18dfu7c9t4cibigud4j4lomm...@4ax.com>,
See here's another one.
YO MATH WHIZ ? if ERD is a diameter then why are rear spokes in two
lengths ?
datakoll
>
> - Show quoted text -
again... ERD is a math constant used to derive spoke lengths. ERD
exists as a measurment, a number not as a spoke length. NOT AS A SPOKE
LENGTH.
butbutbut for some inexplicable reason, Rinard and Brandt go on to
confuse c-o-n-f-u-s-e ERD with spoke length.
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.
Michael Press
<955a21b6-30f9-428d...@u69g2000hse.googlegroups.com>,
datakoll <data...@yahoo.com> wrote:
> 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
datakoll
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???
Tom Sherman
>
> 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
datakoll
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.
datakoll
wrote:
not if they're using spoke clac
oldbi...@earthlink.net
<jevere...@sbcglobal.DEFEAT.UCE.BOTS.net> 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
> 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
> 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.
>
> 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
jim beam
no, it's a variable, not a constant. _one_ of the variables used in the
calculation. different rims have different erd's.
> 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.
>
> 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.
>
> 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.
datakoll
>
> - 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.
John Everett
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.
datakoll
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.
Michael Press
John Everett <jeve...@sbcglobal.DEFEAT.UCE.BOTS.net> wrote:
> 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
Michael Press
<53576498-0053-48e9...@b1g2000hsg.googlegroups.com>,
datakoll <data...@yahoo.com> wrote:
ERD is not spoke length. It is a dimension among others
used to calculate spoke length.
--
Michael Press
Michael Press
<cc12f16d-99fe-4d68...@n36g2000hse.googlegroups.com>,
datakoll <data...@yahoo.com> wrote:
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
datakoll
>
> - 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...
datakoll
suggesting an after calculation deduction may be in order after
examination of nipple and spoke in real time
> 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 -
A Muzi
>>> 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?
> Michael Press <rub...@pacbell.net> wrote:
>> 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.
>> John Everett <jevere...@sbcglobal.DEFEAT.UCE.BOTS.net> wrote:
>>> 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. ;-)
> Michael Press <rub...@pacbell.net> wrote:
>> 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.
>> John Everett <jevere...@sbcglobal.DEFEAT.UCE.BOTS.net> wrote:
>>> 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.
> Michael Press <rub...@pacbell.net> wrote:
>> Asking me? All of them.
>> John Everett <jevere...@sbcglobal.DEFEAT.UCE.BOTS.net> wrote:
>>> 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.
> Michael Press <rub...@pacbell.net> wrote:
>> Are you asking for our advice?
datakoll wrote:
> 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
A Muzi
datakoll
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...
Tom Sherman
> [...]
> Anyway I now have my spokes. With this my participation in these
> threads ends.
>
datakoll
wrote:
my day was ruined