spoke protruding beyond nipple notch

Hi

Am building the wheel featured in a thread with topic "2 cross rear
wheel - not so bad?".

In the end it's being made from a Goldtec track hub, Mavic Open Pro rim
28 hole, Sapim Race spokes, 3 cross pattern.

DT Swiss, Spocalc and another calculator all give me the same answer
for the spoke length: 298 mm. (The pre-defined hub values are correct
in Spocalc.)

However, getting it to the stage where I'm going to be truing and not
just bringing it up to tension, I find that the spokes are already
about 2 mm over the top of the nipple notch! Two other finished wheels
I have handy (same rims, popular hubs, same calculators) have the
nipple about level with the notch.

I don't think the calculations are wrong (but looks like I could have
easily used something like 296mm) ... is this nipple protrusion
actually bad?

ccr

On Sat, 11 Feb 2006 12:25:50 -0800, cccrider wrote:

However, getting it to the stage where I'm going to be truing and not
just bringing it up to tension, I find that the spokes are already
about 2 mm over the top of the nipple notch! Two other finished wheels
I have handy (same rims, popular hubs, same calculators) have the
nipple about level with the notch.

I don't think the calculations are wrong (but looks like I could have
easily used something like 296mm) ... is this nipple protrusion
actually bad?

Nipple notch? You mean the screwdriver slot? 2mm above the bottom of the
slot would just put the spoke at or slightly past the nipple itself.
That's OK.

Ideally the spokes should be right at the bottom of the slot, but a couple
of mm above won't be a problem. Beyond that, though, you run into two
problems: you don't want the spokes long enough to reach the rim tape, or
even worse the tube. You also don't want to get the threads on the spoke
past the threads on the nipple -- a little is OK, but too much and you
have a weaker connection.

--

David L. Johnson

__o | Deserves death! I daresay he does. Many that live deserve
_`\(,_ | death. And some that die deserve life. Can you give it to
(_)/ (_) | them? Then do not be too eager to deal out death in judgement.
-- J. R. R. Tolkein

David L. Johnson wrote:
On Sat, 11 Feb 2006 12:25:50 -0800, cccrider wrote:

However, getting it to the stage where I'm going to be truing and not
just bringing it up to tension, I find that the spokes are already
about 2 mm over the top of the nipple notch! Two other finished wheels
I have handy (same rims, popular hubs, same calculators) have the
nipple about level with the notch.

I don't think the calculations are wrong (but looks like I could have
easily used something like 296mm) ... is this nipple protrusion
actually bad?

Nipple notch? You mean the screwdriver slot? 2mm above the bottom of the
slot would just put the spoke at or slightly past the nipple itself.
That's OK.

Ideally the spokes should be right at the bottom of the slot, but a couple
of mm above won't be a problem. Beyond that, though, you run into two
problems: you don't want the spokes long enough to reach the rim tape, or
even worse the tube. You also don't want to get the threads on the spoke
past the threads on the nipple -- a little is OK, but too much and you
have a weaker connection.

Thanks for the quick answer. So it's pretty much OK. That's good to
know. Nipple notch: so that's why I couldn't get any of the previous
posts on the subject when searching! :-)

Have got about 5mm more until the rim tape for these rims luckily. Am a
bit worried about the last point you made (spoke threads passed the
nipple threads) - it's going to be about 3mm passed the top of the
nipple all round by my estimate.

ccr

ccr wrote:

DT Swiss, Spocalc and another calculator all give me the same answer
for the spoke length: 298 mm. (The pre-defined hub values are correct
in Spocalc.)
However, getting it to the stage where I'm going to be truing and not
just bringing it up to tension, I find that the spokes are already
about 2 mm over the top of the nipple notch! Two other finished wheels
I have handy (same rims, popular hubs, same calculators) have the
nipple about level with the notch.
I don't think the calculations are wrong (but looks like I could have
easily used something like 296mm) ... is this nipple protrusion
actually bad?
ccr

Did you physically measure the rim ERD? Have you checked the length of
the spokes? Were they all the same length & the length you ordered? If
all the spoke lengths are correct, then it might be a good idea to
disassemble the wheel & measure the ERD. From personal experience, I
know it takes little roughness under the tape w/ road air psi.
(100+psi) to cause leaks, even when using good Velox tape. Two layers
of Velox help, but makes removing a tube/tire more difficult. Your
wheel may or may not work. At this point in time, you've lost the cost
of the spokes, the question is time. If you proceed & the wheel flats
due to non road side tube punctures, you've lost the time you put into
the first build. If it works you have won the game.

good luck, John

wrote:
Have got about 5mm more until the rim tape for these rims luckily. Am a
bit worried about the last point you made (spoke threads passed the
nipple threads) - it's going to be about 3mm passed the top of the
nipple all round by my estimate.

Check on a spare spoke and nipple (you do have extras?) and see how
much you have left.

wrote:
David L. Johnson wrote:
On Sat, 11 Feb 2006 12:25:50 -0800, cccrider wrote:

However, getting it to the stage where I'm going to be truing and not
just bringing it up to tension, I find that the spokes are already
about 2 mm over the top of the nipple notch! Two other finished wheels
I have handy (same rims, popular hubs, same calculators) have the
nipple about level with the notch.

I don't think the calculations are wrong (but looks like I could have
easily used something like 296mm) ... is this nipple protrusion
actually bad?

Nipple notch? You mean the screwdriver slot? 2mm above the bottom of the
slot would just put the spoke at or slightly past the nipple itself.
That's OK.

Ideally the spokes should be right at the bottom of the slot, but a couple
of mm above won't be a problem. Beyond that, though, you run into two
problems: you don't want the spokes long enough to reach the rim tape, or
even worse the tube. You also don't want to get the threads on the spoke
past the threads on the nipple -- a little is OK, but too much and you
have a weaker connection.

Thanks for the quick answer. So it's pretty much OK. That's good to
know. Nipple notch: so that's why I couldn't get any of the previous
posts on the subject when searching! :-)

Have got about 5mm more until the rim tape for these rims luckily. Am a
bit worried about the last point you made (spoke threads passed the
nipple threads) - it's going to be about 3mm passed the top of the
nipple all round by my estimate.

ccr

This is a big concern and if you run out of threads on the spoke you're
pretty much screwed. Take an unlaced spoke and nipple from the same
batch and see how far the spoke can actually protrude. I think the way
this works is that with DT it's often a few millimeters, with
Wheelsmith and Sapim it's often .5mm or less if any. In other words,
many spoke/nipple combinations won't let you have any protrusion at
all.

One thing to know about Spocalc and many of the other systems is that
they're based on the pure geometry of the parts and don't compensate
for rim compression or spoke stretch at all. Those 2 factors are enough
to make a big difference. Rims can compress up to around 2mm total and
around half that more or less is normal, and steel spokes stretch
around .3mm to .7mm each depending on gauge, length, and tension. The
rule of the thumb is to always round down a lot... if Spocalc gives me
294.1, I'll just use 292 if it's a light-ish rim and thin spokes, or
293 if it's available and the rim and spokes seem like they're not
gonna stretch/compress enough to mess things up. Using the 294's will
only work with a brand that gives you a ton of protrusion. Rounding
down 2mm doesn't hurt anything, but running out of threads forces you
to... get the shorter spokes anyway, usually.

From where you're, go ahead and see if you can finish the wheel, but
there's some odds it won't work.

john wrote:
ccr wrote:

DT Swiss, Spocalc and another calculator all give me the same answer
for the spoke length: 298 mm. (The pre-defined hub values are correct
in Spocalc.)
However, getting it to the stage where I'm going to be truing and not
just bringing it up to tension, I find that the spokes are already
about 2 mm over the top of the nipple notch! Two other finished wheels
I have handy (same rims, popular hubs, same calculators) have the
nipple about level with the notch.
I don't think the calculations are wrong (but looks like I could have
easily used something like 296mm) ... is this nipple protrusion
actually bad?
ccr

Did you physically measure the rim ERD? Have you checked the length of
the spokes? Were they all the same length & the length you ordered? If
all the spoke lengths are correct, then it might be a good idea to
disassemble the wheel & measure the ERD. From personal experience, I
know it takes little roughness under the tape w/ road air psi.
(100+psi) to cause leaks, even when using good Velox tape. Two layers
of Velox help, but makes removing a tube/tire more difficult. Your
wheel may or may not work. At this point in time, you've lost the cost
of the spokes, the question is time. If you proceed & the wheel flats
due to non road side tube punctures, you've lost the time you put into
the first build. If it works you have won the game.

Length of spokes - yes, this I did check, all OK and same, correct
length.

ERD - probably naive but I didn't bother and just used the 605 mm
quoted (expecting it to be fine).

Even with protrusion, there's another 5mm or so of space between a flat
rim tape over the socket. I don't know whether that's good enough
insurance as I don't know by how much an inner tube bulges into the
socket or whether there's much 'travel' towards the inner tube by the
spoke under riding load.

good luck, John

I might need it!

ccr

wrote:
Have got about 5mm more until the rim tape for these rims luckily. Am a
bit worried about the last point you made (spoke threads passed the
nipple threads) - it's going to be about 3mm passed the top of the
nipple all round by my estimate.

Check on a spare spoke and nipple (you do have extras?) and see how
much you have left. If it isn't enough (but almost) you might get away
with using washers on the nipples... otherwise you need shorter spokes.
You are already at 3x with 28, so you can't increase the x amount...

I'm surprised that the lengths are way off... did you make some mistake
in the calculations or the lacing?

wrote:
Ron Ruff wrote:
wrote:
Have got about 5mm more until the rim tape for these rims luckily. Am a
bit worried about the last point you made (spoke threads passed the
nipple threads) - it's going to be about 3mm passed the top of the
nipple all round by my estimate.

Check on a spare spoke and nipple (you do have extras?) and see how
much you have left.

Yep, I have 2 extras :-)

~ 9 mm thread on a spoke, ~ 10 mm on a nipple so I'm only engaging
about 6 mm (i.e. 2/3 rds) of each spoke's thread. Bad enough to go and
get 296 mm?

ccr

If the spoke is protruding past the nipple, then all the nipple threads
are engaged.

And sorry, I didn't notice in your original post that the spokes were
protruding so much before they even had any tension on them. It's all
about threading a nipple onto an unlaced spoke and seeing if there
happens to be gobs of protrusion available. There probably won't be
enough and you'll probably need to get different spokes. There was
probably an error in calculating.

Spokes poking into the tube is only a problem on shallowish rims, which
Open Pros aren't. I doubt there's any way you could have a spoke/nipple
combo where there was enough protrusion to cover that gap without
running out of spoke threads first.

Nate Knutson wrote:
wrote:
David L. Johnson wrote:
On Sat, 11 Feb 2006 12:25:50 -0800, cccrider wrote:

However, getting it to the stage where I'm going to be truing and not
just bringing it up to tension, I find that the spokes are already
about 2 mm over the top of the nipple notch! Two other finished wheels
I have handy (same rims, popular hubs, same calculators) have the
nipple about level with the notch.

I don't think the calculations are wrong (but looks like I could have
easily used something like 296mm) ... is this nipple protrusion
actually bad?

Nipple notch? You mean the screwdriver slot? 2mm above the bottom of the
slot would just put the spoke at or slightly past the nipple itself.
That's OK.

Ideally the spokes should be right at the bottom of the slot, but a couple
of mm above won't be a problem. Beyond that, though, you run into two
problems: you don't want the spokes long enough to reach the rim tape, or
even worse the tube. You also don't want to get the threads on the spoke
past the threads on the nipple -- a little is OK, but too much and you
have a weaker connection.

Thanks for the quick answer. So it's pretty much OK. That's good to
know. Nipple notch: so that's why I couldn't get any of the previous
posts on the subject when searching! :-)

Have got about 5mm more until the rim tape for these rims luckily. Am a
bit worried about the last point you made (spoke threads passed the
nipple threads) - it's going to be about 3mm passed the top of the
nipple all round by my estimate.

ccr

This is a big concern and if you run out of threads on the spoke you're
pretty much screwed. Take an unlaced spoke and nipple from the same
batch and see how far the spoke can actually protrude. I think the way
this works is that with DT it's often a few millimeters, with
Wheelsmith and Sapim it's often .5mm or less if any. In other words,
many spoke/nipple combinations won't let you have any protrusion at
all.

Turning by hand, I can get the spoke to peep out of the top of the
nipple but, believe it or not, with the spoke key, I can get the nipple
passed the entire spoke thread!

One thing to know about Spocalc and many of the other systems is that
they're based on the pure geometry of the parts and don't compensate
for rim compression or spoke stretch at all. Those 2 factors are enough
to make a big difference. Rims can compress up to around 2mm total and
around half that more or less is normal, and steel spokes stretch
around .3mm to .7mm each depending on gauge, length, and tension. The
rule of the thumb is to always round down a lot... if Spocalc gives me
294.1, I'll just use 292 if it's a light-ish rim and thin spokes, or
293 if it's available and the rim and spokes seem like they're not
gonna stretch/compress enough to mess things up. Using the 294's will
only work with a brand that gives you a ton of protrusion. Rounding
down 2mm doesn't hurt anything, but running out of threads forces you
to... get the shorter spokes anyway, usually.

From where you're, go ahead and see if you can finish the wheel, but
there's some odds it won't work.

I think it can be finished off (is 2/3rds of the thread 'ok'?) but I
may just pop out tomorrow and get the 296s.

Thanks for tip about geometry vs reality. I'll be rounding down in
future!

ccr