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spoke length problem



 
 
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  #1  
Old November 30th 17, 04:58 AM posted to rec.bicycles.tech
Frank Krygowski[_4_]
external usenet poster
 
Posts: 10,538
Default spoke length problem

Warning: Actual bike tech content below.

I'm building up an antique bike for a kid. After a false start with the
original rims (very light, but in a very obscure size) I ended up
replacing the wheels with 20" Sun rims on hubs that I had lying around:
a Campy front hub, and a Shimano 3CC 3 speed rear hub with coaster brake.

I measured both hubs and used Sun's online ERD value of 396mm for the
rim. I plugged dimensions into three different online spoke calculators.
It looked like I could use the same spoke length front and rear if I
went 2x front and 3x rear.

Here were the calculator results:
Sapim said front 189mm, rear 188mm.
DT said 186 front, 186 rear.
United Bicycle Institute said 185.6 front, 185.1 rear.
So I ordered 14 gauge Sapim spokes, 186 front and rear.

The front wheel built up perfectly, as usual. But the rear wheel won't
tension up. The spoke threads are bottoming.

I just double checked my hub dimensions. They seem to be spot on. And
again, everything was perfect in front. The spokes measure 186 with 10mm
of thread. The nipples are 16mm long with an unthreaded 5mm deep hole at
the end that slides over the spoke.

I can think of several possible solutions:

1) buy shorter spokes.

2) sacrifice a few nipple threads by drilling into the end of the nipple
to counterbore another 2mm or so. It's for a little kid, and I doubt
he'll be stressing the wheel very much.

3) acquire a die and extend the spoke threads. The cut threads won't
have a full thread form, but there should be plenty of strength in the
existing threads.

4) put washers under the spoke heads. It's a double wall rim so there's
room in there.

5) and next time, maybe go 2mm shorter than the calculators say? But
why? These spokes aren't stretching. I can't get any tension at all.

I'm curious if anyone's had a similar problem. If so, did you determine
what caused the error? I'm prepared to smack my forehead if necessary.

--
- Frank Krygowski
  #2  
Old November 30th 17, 05:14 AM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 6,374
Default spoke length problem

Real time. ERD is estimate

Use a wheel beam...search here in RBT

Beam rim with hub hole n shim rim up

Then quadrant rim with 3-4 experimental spokes in 4 groups pre measured real
time with tape or steel yardstick - Wal sewing

Then arrive at 'exact' length
  #3  
Old November 30th 17, 05:22 AM posted to rec.bicycles.tech
JBeattie
external usenet poster
 
Posts: 5,870
Default spoke length problem

On Wednesday, November 29, 2017 at 7:58:57 PM UTC-8, Frank Krygowski wrote:
Warning: Actual bike tech content below.

I'm building up an antique bike for a kid. After a false start with the
original rims (very light, but in a very obscure size) I ended up
replacing the wheels with 20" Sun rims on hubs that I had lying around:
a Campy front hub, and a Shimano 3CC 3 speed rear hub with coaster brake.

I measured both hubs and used Sun's online ERD value of 396mm for the
rim. I plugged dimensions into three different online spoke calculators.
It looked like I could use the same spoke length front and rear if I
went 2x front and 3x rear.

Here were the calculator results:
Sapim said front 189mm, rear 188mm.
DT said 186 front, 186 rear.
United Bicycle Institute said 185.6 front, 185.1 rear.
So I ordered 14 gauge Sapim spokes, 186 front and rear.

The front wheel built up perfectly, as usual. But the rear wheel won't
tension up. The spoke threads are bottoming.

I just double checked my hub dimensions. They seem to be spot on. And
again, everything was perfect in front. The spokes measure 186 with 10mm
of thread. The nipples are 16mm long with an unthreaded 5mm deep hole at
the end that slides over the spoke.

I can think of several possible solutions:

1) buy shorter spokes.

2) sacrifice a few nipple threads by drilling into the end of the nipple
to counterbore another 2mm or so. It's for a little kid, and I doubt
he'll be stressing the wheel very much.

3) acquire a die and extend the spoke threads. The cut threads won't
have a full thread form, but there should be plenty of strength in the
existing threads.

4) put washers under the spoke heads. It's a double wall rim so there's
room in there.

5) and next time, maybe go 2mm shorter than the calculators say? But
why? These spokes aren't stretching. I can't get any tension at all.

I'm curious if anyone's had a similar problem. If so, did you determine
what caused the error? I'm prepared to smack my forehead if necessary.



They're too long, obviously. Is lacing 4X a possibility? Otherwise, you buy new spokes. You could also find a shop with a Phil or other spoke cutter.

-- Jay Beattie.

  #4  
Old November 30th 17, 10:23 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
external usenet poster
 
Posts: 10,538
Default spoke length problem

On 11/29/2017 11:22 PM, jbeattie wrote:
On Wednesday, November 29, 2017 at 7:58:57 PM UTC-8, Frank Krygowski wrote:
Warning: Actual bike tech content below.

I'm building up an antique bike for a kid. After a false start with the
original rims (very light, but in a very obscure size) I ended up
replacing the wheels with 20" Sun rims on hubs that I had lying around:
a Campy front hub, and a Shimano 3CC 3 speed rear hub with coaster brake.

I measured both hubs and used Sun's online ERD value of 396mm for the
rim. I plugged dimensions into three different online spoke calculators.
It looked like I could use the same spoke length front and rear if I
went 2x front and 3x rear.

Here were the calculator results:
Sapim said front 189mm, rear 188mm.
DT said 186 front, 186 rear.
United Bicycle Institute said 185.6 front, 185.1 rear.
So I ordered 14 gauge Sapim spokes, 186 front and rear.

The front wheel built up perfectly, as usual. But the rear wheel won't
tension up. The spoke threads are bottoming.

I just double checked my hub dimensions. They seem to be spot on. And
again, everything was perfect in front. The spokes measure 186 with 10mm
of thread. The nipples are 16mm long with an unthreaded 5mm deep hole at
the end that slides over the spoke.

I can think of several possible solutions:

1) buy shorter spokes.

2) sacrifice a few nipple threads by drilling into the end of the nipple
to counterbore another 2mm or so. It's for a little kid, and I doubt
he'll be stressing the wheel very much.

3) acquire a die and extend the spoke threads. The cut threads won't
have a full thread form, but there should be plenty of strength in the
existing threads.

4) put washers under the spoke heads. It's a double wall rim so there's
room in there.

5) and next time, maybe go 2mm shorter than the calculators say? But
why? These spokes aren't stretching. I can't get any tension at all.

I'm curious if anyone's had a similar problem. If so, did you determine
what caused the error? I'm prepared to smack my forehead if necessary.



They're too long, obviously. Is lacing 4X a possibility? Otherwise, you buy new spokes. You could also find a shop with a Phil or other spoke cutter.


4x won't work. That would require roughly 195mm spokes. I happen to have
a set of 170mm spokes (intended for the original odd rims) and the
calculators tell me x2 would need 177mm. So I'm assuming 170 is too short.

I'll see if some shorter nipples might work. If not, I'll probably go
with washers under the spoke nipple heads.

I'm more interested in knowing what might have gone wrong. I've never
had this problem occur before.

I just tried measuring the ERD myself, using a tape measure to get
circumference of the rim tape's surface (1260mm) and a metric vernier
caliper to get the "drop" from that surface to the face of the hollow
rivets on which the spoke head rests (3.8mm). Circumference divided by
pi minus (drop x 2) gives me 393.5mm. From
https://www.sheldonbrown.com/spoke-length.html I get the advice to add a
couple millimeter for the thickness of each nipple head, which gives me
ERD = 397.5mm. That compares well with the online catalog value of 396,
so I'm still baffled.

--
- Frank Krygowski
  #5  
Old November 30th 17, 10:53 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 6,374
Default spoke length problem

Why yawl refuse real time measurement with a simply made device is intolerably STUPID
  #7  
Old December 1st 17, 12:07 AM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 13,447
Default spoke length problem

On 11/30/2017 3:23 PM, Frank Krygowski wrote:
On 11/29/2017 11:22 PM, jbeattie wrote:
On Wednesday, November 29, 2017 at 7:58:57 PM UTC-8, Frank
Krygowski wrote:
Warning: Actual bike tech content below.

I'm building up an antique bike for a kid. After a false
start with the
original rims (very light, but in a very obscure size) I
ended up
replacing the wheels with 20" Sun rims on hubs that I had
lying around:
a Campy front hub, and a Shimano 3CC 3 speed rear hub
with coaster brake.

I measured both hubs and used Sun's online ERD value of
396mm for the
rim. I plugged dimensions into three different online
spoke calculators.
It looked like I could use the same spoke length front
and rear if I
went 2x front and 3x rear.

Here were the calculator results:
Sapim said front 189mm, rear 188mm.
DT said 186 front, 186 rear.
United Bicycle Institute said 185.6 front, 185.1 rear.
So I ordered 14 gauge Sapim spokes, 186 front and rear.

The front wheel built up perfectly, as usual. But the
rear wheel won't
tension up. The spoke threads are bottoming.

I just double checked my hub dimensions. They seem to be
spot on. And
again, everything was perfect in front. The spokes
measure 186 with 10mm
of thread. The nipples are 16mm long with an unthreaded
5mm deep hole at
the end that slides over the spoke.

I can think of several possible solutions:

1) buy shorter spokes.

2) sacrifice a few nipple threads by drilling into the
end of the nipple
to counterbore another 2mm or so. It's for a little kid,
and I doubt
he'll be stressing the wheel very much.

3) acquire a die and extend the spoke threads. The cut
threads won't
have a full thread form, but there should be plenty of
strength in the
existing threads.

4) put washers under the spoke heads. It's a double wall
rim so there's
room in there.

5) and next time, maybe go 2mm shorter than the
calculators say? But
why? These spokes aren't stretching. I can't get any
tension at all.

I'm curious if anyone's had a similar problem. If so, did
you determine
what caused the error? I'm prepared to smack my forehead
if necessary.



They're too long, obviously. Is lacing 4X a possibility?
Otherwise, you buy new spokes. You could also find a shop
with a Phil or other spoke cutter.


4x won't work. That would require roughly 195mm spokes. I
happen to have a set of 170mm spokes (intended for the
original odd rims) and the calculators tell me x2 would need
177mm. So I'm assuming 170 is too short.

I'll see if some shorter nipples might work. If not, I'll
probably go with washers under the spoke nipple heads.

I'm more interested in knowing what might have gone wrong.
I've never had this problem occur before.

I just tried measuring the ERD myself, using a tape measure
to get circumference of the rim tape's surface (1260mm) and
a metric vernier caliper to get the "drop" from that surface
to the face of the hollow rivets on which the spoke head
rests (3.8mm). Circumference divided by pi minus (drop x 2)
gives me 393.5mm. From
https://www.sheldonbrown.com/spoke-length.html I get the
advice to add a couple millimeter for the thickness of each
nipple head, which gives me ERD = 397.5mm. That compares
well with the online catalog value of 396, so I'm still
baffled.


Our calculator gives 185 left & right for that rear wheel.
Sorry but I didn't see any obvious error.

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


  #8  
Old December 1st 17, 12:15 AM posted to rec.bicycles.tech
Frank Krygowski[_4_]
external usenet poster
 
Posts: 10,538
Default spoke length problem

On 11/30/2017 6:07 PM, AMuzi wrote:
On 11/30/2017 3:23 PM, Frank Krygowski wrote:
On 11/29/2017 11:22 PM, jbeattie wrote:
On Wednesday, November 29, 2017 at 7:58:57 PM UTC-8, Frank
Krygowski wrote:
Warning: Actual bike tech content below.

I'm building up an antique bike for a kid. After a false
start with the
original rims (very light, but in a very obscure size) I
ended up
replacing the wheels with 20" Sun rims on hubs that I had
lying around:
a Campy front hub, and a Shimano 3CC 3 speed rear hub
with coaster brake.

I measured both hubs and used Sun's online ERD value of
396mm for the
rim. I plugged dimensions into three different online
spoke calculators.
It looked like I could use the same spoke length front
and rear if I
went 2x front and 3x rear.

Here were the calculator results:
Sapim said front 189mm, rear 188mm.
DT said 186 front, 186 rear.
United Bicycle Institute said 185.6 front, 185.1 rear.
So I ordered 14 gauge Sapim spokes, 186 front and rear.

The front wheel built up perfectly, as usual. But the
rear wheel won't
tension up. The spoke threads are bottoming.

I just double checked my hub dimensions. They seem to be
spot on. And
again, everything was perfect in front. The spokes
measure 186 with 10mm
of thread. The nipples are 16mm long with an unthreaded
5mm deep hole at
the end that slides over the spoke.

I can think of several possible solutions:

1) buy shorter spokes.

2) sacrifice a few nipple threads by drilling into the
end of the nipple
to counterbore another 2mm or so. It's for a little kid,
and I doubt
he'll be stressing the wheel very much.

3) acquire a die and extend the spoke threads. The cut
threads won't
have a full thread form, but there should be plenty of
strength in the
existing threads.

4) put washers under the spoke heads. It's a double wall
rim so there's
room in there.

5) and next time, maybe go 2mm shorter than the
calculators say? But
why? These spokes aren't stretching. I can't get any
tension at all.

I'm curious if anyone's had a similar problem. If so, did
you determine
what caused the error? I'm prepared to smack my forehead
if necessary.


They're too long, obviously. Is lacing 4X a possibility?
Otherwise, you buy new spokes.Â* You could also find a shop
with a Phil or other spoke cutter.


4x won't work. That would require roughly 195mm spokes. I
happen to have a set of 170mm spokes (intended for the
original odd rims) and the calculators tell me x2 would need
177mm. So I'm assuming 170 is too short.

I'll see if some shorter nipples might work. If not, I'll
probably go with washers under the spoke nipple heads.

I'm more interested in knowing what might have gone wrong.
I've never had this problem occur before.

I just tried measuring the ERD myself, using a tape measure
to get circumference of the rim tape's surface (1260mm) and
a metric vernier caliper to get the "drop" from that surface
to the face of the hollow rivets on which the spoke head
rests (3.8mm). Circumference divided by pi minus (drop x 2)
gives me 393.5mm. From
https://www.sheldonbrown.com/spoke-length.html I get the
advice to add a couple millimeter for the thickness of each
nipple head, which gives me ERD = 397.5mm. That compares
well with the online catalog value of 396, so I'm still
baffled.


Our calculator gives 185 left & right for that rear wheel.
Sorry but I didn't see any obvious error.

Thanks for checking. At least I don't have to slap my forehead just yet.

--
- Frank Krygowski
  #9  
Old December 1st 17, 02:45 AM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 13,447
Default spoke length problem

On 11/30/2017 5:15 PM, Frank Krygowski wrote:
On 11/30/2017 6:07 PM, AMuzi wrote:
On 11/30/2017 3:23 PM, Frank Krygowski wrote:
On 11/29/2017 11:22 PM, jbeattie wrote:
On Wednesday, November 29, 2017 at 7:58:57 PM UTC-8, Frank
Krygowski wrote:
Warning: Actual bike tech content below.

I'm building up an antique bike for a kid. After a false
start with the
original rims (very light, but in a very obscure size) I
ended up
replacing the wheels with 20" Sun rims on hubs that I had
lying around:
a Campy front hub, and a Shimano 3CC 3 speed rear hub
with coaster brake.

I measured both hubs and used Sun's online ERD value of
396mm for the
rim. I plugged dimensions into three different online
spoke calculators.
It looked like I could use the same spoke length front
and rear if I
went 2x front and 3x rear.

Here were the calculator results:
Sapim said front 189mm, rear 188mm.
DT said 186 front, 186 rear.
United Bicycle Institute said 185.6 front, 185.1 rear.
So I ordered 14 gauge Sapim spokes, 186 front and rear.

The front wheel built up perfectly, as usual. But the
rear wheel won't
tension up. The spoke threads are bottoming.

I just double checked my hub dimensions. They seem to be
spot on. And
again, everything was perfect in front. The spokes
measure 186 with 10mm
of thread. The nipples are 16mm long with an unthreaded
5mm deep hole at
the end that slides over the spoke.

I can think of several possible solutions:

1) buy shorter spokes.

2) sacrifice a few nipple threads by drilling into the
end of the nipple
to counterbore another 2mm or so. It's for a little kid,
and I doubt
he'll be stressing the wheel very much.

3) acquire a die and extend the spoke threads. The cut
threads won't
have a full thread form, but there should be plenty of
strength in the
existing threads.

4) put washers under the spoke heads. It's a double wall
rim so there's
room in there.

5) and next time, maybe go 2mm shorter than the
calculators say? But
why? These spokes aren't stretching. I can't get any
tension at all.

I'm curious if anyone's had a similar problem. If so, did
you determine
what caused the error? I'm prepared to smack my forehead
if necessary.


They're too long, obviously. Is lacing 4X a possibility?
Otherwise, you buy new spokes. You could also find a shop
with a Phil or other spoke cutter.

4x won't work. That would require roughly 195mm spokes. I
happen to have a set of 170mm spokes (intended for the
original odd rims) and the calculators tell me x2 would need
177mm. So I'm assuming 170 is too short.

I'll see if some shorter nipples might work. If not, I'll
probably go with washers under the spoke nipple heads.

I'm more interested in knowing what might have gone wrong.
I've never had this problem occur before.

I just tried measuring the ERD myself, using a tape measure
to get circumference of the rim tape's surface (1260mm) and
a metric vernier caliper to get the "drop" from that surface
to the face of the hollow rivets on which the spoke head
rests (3.8mm). Circumference divided by pi minus (drop x 2)
gives me 393.5mm. From
https://www.sheldonbrown.com/spoke-length.html I get the
advice to add a couple millimeter for the thickness of each
nipple head, which gives me ERD = 397.5mm. That compares
well with the online catalog value of 396, so I'm still
baffled.


Our calculator gives 185 left & right for that rear wheel.
Sorry but I didn't see any obvious error.

Thanks for checking. At least I don't have to slap my
forehead just yet.


Because Shimano tricoaster and the trig are well known, I
suspect the actual ERD is not what we assume. There are
several rims whose dies were changed over the years with
various retoolings.

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


  #10  
Old November 30th 17, 07:15 AM posted to rec.bicycles.tech
John B.[_3_]
external usenet poster
 
Posts: 5,697
Default spoke length problem

On Wed, 29 Nov 2017 22:58:52 -0500, Frank Krygowski
wrote:

Warning: Actual bike tech content below.

I'm building up an antique bike for a kid. After a false start with the
original rims (very light, but in a very obscure size) I ended up
replacing the wheels with 20" Sun rims on hubs that I had lying around:
a Campy front hub, and a Shimano 3CC 3 speed rear hub with coaster brake.

I measured both hubs and used Sun's online ERD value of 396mm for the
rim. I plugged dimensions into three different online spoke calculators.
It looked like I could use the same spoke length front and rear if I
went 2x front and 3x rear.

Here were the calculator results:
Sapim said front 189mm, rear 188mm.
DT said 186 front, 186 rear.
United Bicycle Institute said 185.6 front, 185.1 rear.
So I ordered 14 gauge Sapim spokes, 186 front and rear.

The front wheel built up perfectly, as usual. But the rear wheel won't
tension up. The spoke threads are bottoming.

I just double checked my hub dimensions. They seem to be spot on. And
again, everything was perfect in front. The spokes measure 186 with 10mm
of thread. The nipples are 16mm long with an unthreaded 5mm deep hole at
the end that slides over the spoke.

I can think of several possible solutions:

1) buy shorter spokes.

2) sacrifice a few nipple threads by drilling into the end of the nipple
to counterbore another 2mm or so. It's for a little kid, and I doubt
he'll be stressing the wheel very much.

3) acquire a die and extend the spoke threads. The cut threads won't
have a full thread form, but there should be plenty of strength in the
existing threads.

4) put washers under the spoke heads. It's a double wall rim so there's
room in there.

5) and next time, maybe go 2mm shorter than the calculators say? But
why? These spokes aren't stretching. I can't get any tension at all.

I'm curious if anyone's had a similar problem. If so, did you determine
what caused the error? I'm prepared to smack my forehead if necessary.


Quite a lot of shops over here no longer stock threaded spokes but cut
to length and thread (would one call them) blank spokes so assuming
sufficient full diameter size it should be no problem in threading the
spokes a little further. Assuming, of course that you can get the
proper die. I include that comment as I once threaded some spokes a
bit too far and a number of them stripped the threads out of the
nipples as there wasn't sufficient thread contact :-(

I believe that might be a better scheme then counter boring the
nipples although the usual standard for thread length is one diameter
for full strength so I would assume that something like 1-1/2 to 2
thread diameter would be sufficient even in brass nipples. Or
alternatively use washers under the nipple head.

I believe that someone else mentioned it but can you go X4 on the rear
wheel?

Re calculators. The old chap that runs (I think) the oldest bike shop
in Phuket, Thailand doesn't use any sort of calculator. He has, what I
think is, some sort of special steel ruler and he measures the rim to
flange distance with the wheel and hub laying on the floor. After he
measures things he pauses and looks wise for a moment and says
something like, "Yup, 265.4, that'll do her" and gets down the 265.5
spoke box :-)
--
Cheers,

John B.

 




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