Minimum Spoke Thread Engagement

bigsky said:

I'm building a wheel using a rim with no official source of dimensions
(Mavic Rimtec 190FB). I measured the effective rim diameter and fed
this and selected Campy 10 speed hub (Centaur) into the DT Swiss
calculator. I also did the calculations by hand as a double check, and
they agreed (292mm/294mm). However, it seems the numbers come out
slightly short. I had trouble getting all the spokes to engage the
nipples during cross (3) and now with all spokes engaged but not
tensioned, I count about 5 turns. I estimate that I have about 2.3mm of
thread engagement, but it does not look like I will get full thread
engagement to where the spoke is flush with the nipple end. Will this
be enough thread engagement to ensure full strength? I would like to be
sure before I tension and set the spokes in the new hub.

Thanks,
bigsky

as far as mechanical strength is concerned, you only need 3 threads. as
far as vibratory loosening is concerned however, you need a few more.
spokes also traditionally have more thread engagement for ease of build
and any subsequent adjustment. with this in mind, i'd be inclined to
get a new set of spokes & rebuild.

rims are not by nature round as the calculator sez rims are
nor is the hub naturally centered until an average is achieved.

Quoted message said:

rims are not by nature round as the calculator sez rims are
nor is the hub naturally centered until an average is achieved.

right, and that's part of the reason why you need a little extra
threading - to allow for variance.

bigsky said:

I'm building a wheel using a rim with no official source of dimensions
(Mavic Rimtec 190FB). I measured the effective rim diameter and fed
this and selected Campy 10 speed hub (Centaur) into the DT Swiss
calculator. I also did the calculations by hand as a double check,
and they agreed (292mm/294mm). However, it seems the numbers come out
slightly short. I had trouble getting all the spokes to engage the
nipples during cross (3) and now with all spokes engaged but not
tensioned, I count about 5 turns. I estimate that I have about 2.3mm
of thread engagement, but it does not look like I will get full thread
engagement to where the spoke is flush with the nipple end. Will this
be enough thread engagement to ensure full strength? I would like to
be sure before I tension and set the spokes in the new hub.

I don't know how loose the wheel is now, but it sounds like you will
get at least a couple more turns as you tension the wheel, bringing
the total up to, what, about 7 threads engaged? Thats plenty, nothing
bad will happen using the wheel like that.

It sounds like you did the calculation correctly, so one of two things
must be going on. Either you measured the rim incorrectly, or the
wheel is really loose now and you really do have the correct size
spokes.

Anyways, I have never heard of spokes being returnable, so you might
as well use what you have got, unless you have some other use for
those spokes.

"Jim Smith" wrote: (clip) you might as well use what you have got (clip)
^^^^^^^^^^^^^^^
Or, you could "split the difference." You could put aside the 292 mm
spokes, and move the 294's to that side. And go out and buy some longer
spokes for one side only.

bigsky said:

I'm building a wheel using a rim with no official source of dimensions
(Mavic Rimtec 190FB). I measured the effective rim diameter and fed
this and selected Campy 10 speed hub (Centaur) into the DT Swiss
calculator. I also did the calculations by hand as a double check, and
they agreed (292mm/294mm). However, it seems the numbers come out
slightly short. I had trouble getting all the spokes to engage the
nipples during cross (3) and now with all spokes engaged but not
tensioned, I count about 5 turns. I estimate that I have about 2.3mm of
thread engagement, but it does not look like I will get full thread
engagement to where the spoke is flush with the nipple end. Will this
be enough thread engagement to ensure full strength? I would like to be
sure before I tension and set the spokes in the new hub.

Firstly, are you sure you got the first spoke on the second side of the
wheel in the correct place? If you didn't, 8 (or 9) spokes will appear
to be too short, and 8 (or 9) will appear to be too long.

Secondly, did you remember to add the length of the nipples when
measuring the ERD, assuming you took the measurement between two
opposite nipples?

If the wheel is built correctly and the spokes are ALL too short, I
would buy new ones and start again. At least you'll know the exact
length you need this time!

Zog The Undeniable said:

bigsky said:

I'm building a wheel using a rim with no official source of

dimensions

Quoted message said:

Quoted message said:

(Mavic Rimtec 190FB). I measured the effective rim diameter and

fed

Quoted message said:

Quoted message said:

this and selected Campy 10 speed hub (Centaur) into the DT Swiss
calculator. I also did the calculations by hand as a double check,

and

Quoted message said:

Quoted message said:

they agreed (292mm/294mm). However, it seems the numbers come out
slightly short. I had trouble getting all the spokes to engage the

Quoted message said:

Quoted message said:

nipples during cross (3) and now with all spokes engaged but not
tensioned, I count about 5 turns. I estimate that I have about

2.3mm of

Quoted message said:

Quoted message said:

thread engagement, but it does not look like I will get full thread

Quoted message said:

Quoted message said:

engagement to where the spoke is flush with the nipple end. Will

this

Quoted message said:

Quoted message said:

be enough thread engagement to ensure full strength? I would like

to be

Quoted message said:

Quoted message said:

sure before I tension and set the spokes in the new hub.

Firstly, are you sure you got the first spoke on the second side of

the

Quoted message said:

wheel in the correct place? If you didn't, 8 (or 9) spokes will

appear

Quoted message said:

to be too short, and 8 (or 9) will appear to be too long.

Secondly, did you remember to add the length of the nipples when
measuring the ERD, assuming you took the measurement between two
opposite nipples?

If the wheel is built correctly and the spokes are ALL too short, I
would buy new ones and start again. At least you'll know the exact
length you need this time!

Tighten those spokes, true up the wheel, pre-stess it, tighten again to
the optimum tension and ride it! Life's too short for nitpicking and
perfectionism.

But I hope you used linseed oil or spokeprep. Then that wheel's
guaranteed!

Quoted message said:

...
But I hope you used linseed oil or spokeprep. Then that wheel's
guaranteed!

Trolling for Jobst Brandt?

--
Tom Sherman - Earth (Downstate Illinois, North of Forgottonia)

"bigsky" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I'm building a wheel using a rim with no official source of dimensions
(Mavic Rimtec 190FB). I measured the effective rim diameter and fed
this and selected Campy 10 speed hub (Centaur) into the DT Swiss
calculator. I also did the calculations by hand as a double check, and
they agreed (292mm/294mm). However, it seems the numbers come out
slightly short. I had trouble getting all the spokes to engage the
nipples during cross (3) and now with all spokes engaged but not
tensioned, I count about 5 turns. I estimate that I have about 2.3mm of
thread engagement, but it does not look like I will get full thread
engagement to where the spoke is flush with the nipple end. Will this
be enough thread engagement to ensure full strength? I would like to be
sure before I tension and set the spokes in the new hub.

Thanks,
bigsky

Can you get longer spoke nipples?
16mm nipples in place of the normal 12mm ones may give you 4mm of extra
thread engagement.

It doesn't work that way, they both have the same amount of threads.

Or, in a perfect world, don't use linseed oil or spokeprep (although I
go with Jobst 99% of the time).

In message <[email hidden]>, Rudge
<[email hidden]> writes

Quoted message said:

"bigsky" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I'm building a wheel using a rim with no official source of dimensions
(Mavic Rimtec 190FB). I measured the effective rim diameter and fed
this and selected Campy 10 speed hub (Centaur) into the DT Swiss
calculator. I also did the calculations by hand as a double check, and
they agreed (292mm/294mm). However, it seems the numbers come out
slightly short. I had trouble getting all the spokes to engage the
nipples during cross (3) and now with all spokes engaged but not
tensioned, I count about 5 turns. I estimate that I have about 2.3mm of
thread engagement, but it does not look like I will get full thread
engagement to where the spoke is flush with the nipple end. Will this
be enough thread engagement to ensure full strength? I would like to be
sure before I tension and set the spokes in the new hub.

Thanks,
bigsky

Can you get longer spoke nipples?
16mm nipples in place of the normal 12mm ones may give you 4mm of extra
thread engagement.

In the case of DT Swiss you get some extra but not the full extra on
the nipple length. On the ones I bought a couple of weeks ago there is a
useful 2mm extra thread on 16mm nipples as against 12mm ones.

In a previous discussion on this, several posters were very certain that
longer nipples gave no extra thread so I expect that is true of some
brands.

--

Martyn Aldis, e-mail [email hidden]
==============================================================================

<[email hidden]> wrote: It doesn't work that way, they both have the
same amount of threads.
^^^^^^^^^^^^^
But, aren't the threads farther above the rim?

Quoted message said:

<[email hidden]> wrote: It doesn't work that way, they both have the
same amount of threads.

Leo Lichtman said:

But, aren't the threads farther above the rim?

The nipples I use are threaded to the same depth whether
12mm or 16mm overall.

Others report some brands with 2mm difference.

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

"Martyn Aldis" wrote: In a previous discussion on this, several posters
were very certain that

Quoted message said:

longer nipples gave no extra thread so I expect that is true of some
brands.

^^^^^^^^^^^^^^^
I'm not arguing, but I am very puzzled. What would be the reason for making
nipples taller without bringing the thread all the way to the top?

Leo Lichtman said:

"Martyn Aldis" wrote: In a previous discussion on this, several posters
were very certain that

Quoted message said:

longer nipples gave no extra thread so I expect that is true of some
brands.

^^^^^^^^^^^^^^^
I'm not arguing, but I am very puzzled. What would be the reason for making
nipples taller without bringing the thread all the way to the top?

Dear Leo,

Cosmetics? The smooth threadless bore hides otherwise
exposed threads, and looks impressively stronger, even
though it isn't:

http://www.yellowjersey.org/photosfromthepast/NIPPLES.JPG

Here's the thread that Martyn may have had in mind:

http://groups.google.co.uk/groups?q=dear+carl+threads+well&hl=en&lr=&group=rec.bicycles.tech&scoring=d&selm=68BTd.4254%24KT4.2760%40fe07.usenetserver.com&rnum=3

Thanks for the opportunity to use "smooth threadless bore"
again.

Carl Fogel

Leo Lichtman said:

Quoted message said:

In a previous discussion on this, several posters were very certain
that longer nipples gave no extra thread so I expect that is true
of some brands.

Quoted message said:

I'm not arguing, but I am very puzzled. What would be the reason
for making nipples taller without bringing the thread all the way to
the top?

I have plenty of 25.4mm long spoke nipples formerly used for wood
rims. These have about as many threads at the head end as current
shorter nipples have and have a smooth bore to the end with the spoke
wrench flats. As I see it, the intent is to not have the brass nipple
bear the spoke load in tension. Cutting a deep thread also costs more
(time) and offers no advantage, assuming the wheel is built with the
proper parts.

Another reason for this might have come from times when spokes had cut
instead of rolled threads so that engagement beyond the end of the
thread was not possible because it would bind on the unthreaded part
of the spoke that was the same diameter as the major thread diameter.

[email hidden]

Quoted message said:

"Martyn Aldis" wrote: In a previous discussion on this, several posters
were very certain that

Quoted message said:

longer nipples gave no extra thread so I expect that is true of some
brands.

Leo Lichtman said:

I'm not arguing, but I am very puzzled. What would be the reason for making
nipples taller without bringing the thread all the way to the top?

I believe just aesthetics. Once, wood (or plastic) filled
rims required a longer nipple ( with a shallower head) but
those are long gone.

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

Quoted message said:

Leo Lichtman said:

Quoted message said:

In a previous discussion on this, several posters were very certain
that longer nipples gave no extra thread so I expect that is true
of some brands.

I'm not arguing, but I am very puzzled. What would be the reason
for making nipples taller without bringing the thread all the way to
the top?

Quoted message said:

I have plenty of 25.4mm long spoke nipples formerly used for wood
rims. These have about as many threads at the head end as current
shorter nipples have and have a smooth bore to the end with the spoke
wrench flats. As I see it, the intent is to not have the brass nipple
bear the spoke load in tension. Cutting a deep thread also costs more
(time) and offers no advantage, assuming the wheel is built with the
proper parts.

Another reason for this might have come from times when spokes had cut
instead of rolled threads so that engagement beyond the end of the
thread was not possible because it would bind on the unthreaded part
of the spoke that was the same diameter as the major thread diameter.

I truly do not know. When were spoke threads cut? Rolled
threads (Cyclo thread rolling machine) go back to at least
the fifties.

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