Spoke threads exposed on new wheel - Safe?

Last night, I built a new rear wheel for cross riding using a Record
36 hole hubs, a Ritchey OCR Comp rim (called Trekking on web site) and
DT 14/15 spokes.

In doing the research, I noticed that Ritchey's web site gave the ERD
as 596 mm whereas Damon Rinard's Spocalc gave it as 605 mm. Perhaps
Ritchey has redesigned the rims?

At any rate, I called Ritchey and the rep talked to a wheel builder
who gave the ERD 599. Hmm... Right between the two values...

I plugged the 599 value in Spocalc and built the wheel using 290's on
the left and 288's on the right. At this point, I've tensioned them
to 70 kg on the left and 115 on the right.

On inspection, I noticed that the left side as 2-3 threads exposed all
around whereas the right side has 5-6 threads exposed. I'm comcerned
that the spokes are too short and I don't have enough threads embedded
in the brass nipples.

Is this wheel safe or should I rebuild it with longer spokes?

Thx, Dave

In article ,
says...
Last night, I built a new rear wheel for cross riding using a Record
36 hole hubs, a Ritchey OCR Comp rim (called Trekking on web site) and
DT 14/15 spokes.
In doing the research, I noticed that Ritchey's web site gave the ERD
as 596 mm whereas Damon Rinard's Spocalc gave it as 605 mm. Perhaps
Ritchey has redesigned the rims?
At any rate, I called Ritchey and the rep talked to a wheel builder
who gave the ERD 599. Hmm... Right between the two values...
I plugged the 599 value in Spocalc and built the wheel using 290's on
the left and 288's on the right. At this point, I've tensioned them
to 70 kg on the left and 115 on the right.
On inspection, I noticed that the left side as 2-3 threads exposed all
around whereas the right side has 5-6 threads exposed. I'm comcerned
that the spokes are too short and I don't have enough threads embedded
in the brass nipples.
Is this wheel safe or should I rebuild it with longer spokes?

I would rebuild with the proper length spoke. I sounds like your spokes
are too short by a few mm. If you look at your spoke nipples you can see
that they are not threaded all the way. About half the nipple is unthreaded.
So if you can see exposed threads, there are more unexposed threads that
are not engaging the nipple.
---------------
Alex

Alex Rodriguez wrote:
In article ,
says...
Last night, I built a new rear wheel for cross riding using a Record 36
hole hubs, a Ritchey OCR Comp rim (called Trekking on web site) and DT
14/15 spokes. In doing the research, I noticed that Ritchey's web site
gave the ERD as 596 mm whereas Damon Rinard's Spocalc gave it as 605
mm. Perhaps Ritchey has redesigned the rims? At any rate, I called
Ritchey and the rep talked to a wheel builder who gave the ERD 599.
Hmm... Right between the two values... I plugged the 599 value in
Spocalc and built the wheel using 290's on the left and 288's on the
right. At this point, I've tensioned them to 70 kg on the left and 115
on the right. On inspection, I noticed that the left side as 2-3
threads exposed all around whereas the right side has 5-6 threads
exposed. I'm comcerned that the spokes are too short and I don't have
enough threads embedded in the brass nipples. Is this wheel safe or
should I rebuild it with longer spokes?
I would rebuild with the proper length spoke. I sounds like your spokes
are too short by a few mm. If you look at your spoke nipples you can see
that they are not threaded all the way. About half the nipple is
unthreaded. So if you can see exposed threads, there are more unexposed
threads that are not engaging the nipple.
---------------
Alex


I agree with Alex. On the Spoke Calc site there is a way to measure ERD:
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. If you want to measure your own rim (recommended, just to be
sure), then follow these instructions:

Insert two old spokes into holes exactly opposite each other on the rim.
Count holes to be sure. Screw some nipples onto the spokes. Pull them
tight and measure dimension A in the figure (the diameter to the edge of
the nipples, where the spokes dissapears into them). Do this at several
spots around the rim and average the measurements. Measure the length of
a nipple (dimension B in the figure) and add it twice (once for each
nipple). The result is Effective Rim Diameter (ERD). Thus, ERD = A + 2B.

Effective Rim Diameter (ERD) is the dimension you type into the
spreadsheet for "ERD, effective rim diameter". Of all the dimensions you
actually might measure, ERD is the most critical dimension affecting
spoke length, so it makes sense to measure it a few times at different
places around the rim. Always count to make sure you use spoke holes
that are actually opposite each other!

It is a pain to get the wheel built and find out the spokes aren't the
correct length. The Ritchey PRO Trekker Girders I have measure ERD 605
mm. I used 294 mm right and 296 mm left. The spoke length came in fine
on my Shimano XTR and DURA ACE hubs.



--
David Ornee, Western Springs, IL USA

David Ornee, Western Springs, IL USA

--------------------------
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daveornee wrote:



I agree with Alex. On the Spoke Calc site there is a way to measure ERD:
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. If you want to measure your own rim (recommended, just to be
sure), then follow these instructions:



The OP has the advantage of an easy of way of calculating what size
spokes to use for his rebuild: whatever size he used + the length of
exposed thread!

--Josh

Josh Gatts wrote in message om...
daveornee wrote:



I agree with Alex. On the Spoke Calc site there is a way to measure ERD:
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. If you want to measure your own rim (recommended, just to be
sure), then follow these instructions:



The OP has the advantage of an easy of way of calculating what size
spokes to use for his rebuild: whatever size he used + the length of
exposed thread!

--Josh

Dear Josh,

You practical devil! Even if there are objections that I
can't imagine, I admire your approach.

You probably know the apocryphal story of Edison asking a
college graduate who wanted to work in his lab to determine
the volume of an empty glass light bulb.

After the slide-rule expert finished laboriously measuring
curves and calculating an approximate answer, Edison taught
him a practical lesson by filling the bulb with water,
pouring the water into a graduated cylinder, and announcing
the exact volume.

Thanks,

Carl Fogel

On Sat, 01 Nov 2003 01:52:20 GMT Josh Gatts
wrote:


The OP has the advantage of an easy of way of calculating what size
spokes to use for his rebuild: whatever size he used + the length of
exposed thread!

Rather than concentrate on the exposed thread, which is only part of
the unengaged thread, he should measure from the other side of the
spoke nipple. Measure how far down below the spoke head the end of the
spoke stops. You can do this rather easily with a bit of wire, or a
paper clip, or even screw in a loose spoke from above and count turns.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------

"Jim Adney" wrote in message
...
On Sat, 01 Nov 2003 01:52:20 GMT Josh Gatts
wrote:


The OP has the advantage of an easy of way of calculating what size
spokes to use for his rebuild: whatever size he used + the length of
exposed thread!

Rather than concentrate on the exposed thread, which is only part of
the unengaged thread, he should measure from the other side of the
spoke nipple. Measure how far down below the spoke head the end of the
spoke stops. You can do this rather easily with a bit of wire, or a
paper clip, or even screw in a loose spoke from above and count turns.


You could also measure the length of a nipple to the base of the slot (N),
the length of the threading (T) on a spoke, and the length of exposed thread
(E). If your existing spoke is length L, you buy spokes of length L + N - T
+ E. Heh heh.

It's fun to come up with these things, but in reality a couple of unengaged
threads aren't the end of the world (6 *exposed* threads, which is what the
OP was talking about, are more than I would accept, though.) I would
personally just do the easiest thing (the way I originally recommended,
IMHO), and maybe add 1mm to account for the fact that the threads begin a
little way into the nipple.

I just noticed that Peter Chisholm has recommended just replacing the nips
with 16mm. That's probably the best & cheapest solution, although it may
look a little goofy.

Thanks for the idears.

--Josh

or (B): simply measure the depth of the hole from the bead diameter,
622-mm for a 700c. don't forget to 2x it.

"B.C. Cletta" wrote:
or (B): simply measure the depth of the hole from the bead diameter,
622-mm for a 700c. don't forget to 2x it.

Ooh, I never heard that one. Clever!

Art Harris

B.C. Cletta wrote:
: or (B): simply measure the depth of the hole from the bead diameter,
: 622-mm for a 700c. don't forget to 2x it.

Is that 622mm consistent for different rims? When I swap my front and rear
wheels on my truing stand, I have to adjust the vertical truing doohickey by
about 1mm.

- mark