Another day with wheel work (details omitted).
A customer brought in an ITLAB45 wheel for work.
Today I'm only touching the front wheel though.
DT180 straight spoke hub, 24H
Pillar brand custom titanium spokes, built with forced left-right 2-cross lacing
with all final crosses on both wheels built from both sides.
The reason this wheel came in was
that the nipples kept coming loose.
It was apparently sent to ITLAB once for repair,
but it started loosening again after that.
The wheel came with an instruction manual full of dubious nonsense,
but before reading that, from what the customer told me,
the wheel's initial state had slack tension,
and when it came back it was pulled tight as a drum.
I don't necessarily object to building wheels with lower spoke tension
if there are compelling reasons informed by weighing all factors
that make it the best choice,
but building a wheel with low tension that doesn't loosen easily
is genuinely difficult work.
If the person who built this wheel had some clear policy or philosophy
about deliberately building with lower tension, that itself isn't something I'd dispute,
but the fact that the customer could feel a huge difference in tension
between before sending it out and after getting it back—
that means there's no consistency in spoke tension.
If you're going to pull it tight, pull it tight from the start, you know?
That's what I was thinking before I even read the manual.
I did tell the customer "why not send it back to ITLAB?"
but they were concerned it would just happen again if the same place looked at it,
so we decided to have our shop handle it.
In the end, I was able to identify what was causing the loosening.
But reading the manual,
it says not to tension the spokes above 110 kgf.
The "reference" spoke tension is given as
100–105 kgf for both the brake side of the front wheel and the drive side of the rear wheel.
The phrasing "reference spoke tension" rather than specified, recommended, or maximum,
and the distinction between "brake side" and "drive side" is verbatim from the original manual, just so you know.
No, this doesn't make sense.
The customer definitely felt a clear difference in tension before and after sending it in,
but was the pre-send state 100 kgf and the returned state 105 kgf?
There's no way a 5 kgf difference would be noticeable enough to be that obvious, which is one thing.
The other thing is: no matter how precise your rim and low-tolerance your spokes are,
no matter how tight you chase runout when building a wheel,
it's impossible to keep spoke tension variation on one side of a wheel
within 5 kgf using materials that exist in reality.
For example, say you build a 24H wheel with the high-tension side bottom at 105 kgf
(of course, with radial and lateral runout chased down and center perfectly true—that's a baseline assumption).
Then several of the 12 spokes on that side will exceed 110 kgf.
So if you're going to build without ever exceeding 110 kgf,
your only option is to set the ceiling at 105 kgf for the wheel build.
But then several of those 12 spokes on one side will drop below 100 kgf.
That's just unavoidable.
If the returned wheel's high-tension side doesn't exceed 110 kgf on a single spoke,
then there's no way the original wheel was built at 100–105 kgf.
Also, the manual says you can measure this wheel's spoke tension with a DT tension meter,
but not with Park Tool's TM-1 or Hozan. That's wrong.
For this job, I'm disassembling the wheel and rebuilding it
with the same pre-delivery tension but with the nipples less prone to loosening,
and I took the maximum H1ST reading from the 12 high-tension spokes,
then used that as reference for rebuilding—so a Hozan tension meter
can build this wheel just fine.
I did use the DT tension meter since it was specified,
but when I measured both D1ST and H1ST against a given second ST (spoke tension in the conventional sense),
the Hozan didn't detect any values that deviated from its normal parabolic curve of first ST vs. second ST—which is what you'd expect.
Actually, through this work I created a conversion chart from D1ST to second ST to H1ST,
so now with Hozan's tension meter I can build wheels with these same spokes going forward.
The Park Tool TM-1 has issues with unit-to-unit variation and the fact that reducing friction in the sliding parts (including lubrication)
makes the needle go up more easily, but as long as you're careful to use one unit consistently under similar conditions,
it's practically fine.
Since DT and Hozan tension meters are extremely expensive,
the TM-1's value is huge for hobby-level wheel building where that's out of reach.
I loosened the nipples.
These nipples turn from the outside,
and the manual says never grab the inside.
I agree with that. I wouldn't do it anyway.
These nipples have abnormally deep thread pockets—
when you press a spoke in without turning it,
the spoke threads are nearly hidden by how deep the pocket is.
A brittle locking compound was used,
but this only prevents initial loosening and doesn't really increase
friction resistance in the threaded area itself.
In fact, after the contact pressure between the nipple and rim let off,
it turned very easily.
There's another reason for that (more on this later).
↑That beast
With deep thread pockets, the brittle compound residue is long too.
I should have mentioned this earlier, but the pre-work state had
a centering error about the thickness of one sheet of paper.
Depending on the centering gauge, it would get a perfect reading,
so I'd say the center was true.
I recorded all D1ST and H1ST values from the high-tension side before work.
I'm careful to note that spoke tension barely changed before and after work.
There was also tape marking where loosening occurred, on a rear wheel spoke,
but knowing that, I worked on the front wheel first.
Since I know the H1ST on the high-tension side of the front wheel,
I could now build the rear wheel to reference tension
even if the hub, rim, and spokes came to me as loose components.
The most dangerous thing about this wheel is
that they applied generous anti-seize compound to the spoke threads
because they're titanium spokes.
Of course that's going to loosen. There's no way it won't.
This is the cause of loosening I mentioned at the start,
and why the nipples turned so easily after I removed that brittle locking agent earlier.
Maybe the person who built this wheel will claim there's no causal relationship
between applying grease to the threads and nipple loosening,
but given that this wheel has a solid track record of loosening even after being reworked
(whether they rebuilt it completely or just re-tensioned without disassembling, who knows),
any claim like that would have zero credibility.
With brittle locking compound on the spokes,
you can't pull the spokes out of the hub flanges.
Anti-seize compound ended up on the hub flange area,
but I cleaned that off later.
↑12 spokes from one side
I tilted a stainless steel pan and sprayed parts cleaner along one edge.
The particulates in the grease convected and swirled around.
I call this a shortcut, but the left and right spokes were the same length.
I did separate them into original-right and original-left,
but given how expensive these spokes are per unit (though still only about 6 times the cost of CX-RAY),
maybe they wanted to reduce the variety of spare spoke inventory.
Feel free to make excuses after the fact—like "disc brake fronts with this little offset
are fine with the same length!" I don't care.
It just tells me the builder had that level of understanding about spoke length
when they were building the wheel.
The 12 original-right spokes weighed 33.3g, and
the 12 original-left spokes were 33.4g.
All 24 came to 66.7g.
The spoke length was 275mm, so spoke specific gravity is
66.7 (g) ÷ 275 (mm) ÷ 24 (spokes) = 0.010106...,
and dividing that by a 100% reference value of 0.0257 gives
0.0393... = 39.3%.
Straight spokes lack the necked-down portion that bent spokes have
in the spoke length measurement but include in the weight,
so spoke specific gravity tends to come out slightly low.
For estimation purposes, 40% is fine.
On some of the original-right spokes (non-rotor side, low-tension side),
there were wear marks from rubbing at the final cross.
I also cleaned the nipples.
The image above isn't the nipples soaking in the parts cleaner I used on the spokes—
it's fresh cleaner sprayed after washing the pan,
so all the grime shown is purely from the nipples.
↑Like this when you tilt the pan and drip cleaner along an edge
Parts cleaner is just preliminary cleaning.
I also ran them through ultrasonic cleaning.
The image above shows the nipples submerged.
Right after I hit the switch, black hazy grime poured from the nipple holes,
but I couldn't capture that on camera.
This rim doesn't look like an offset rim.
Even if it's not an offset rim, there's a possibility that there was once a sticker
saying something like "orient this side toward the disc rotor mount on disc-brake fronts
and toward the freewheel body on the rear,"
and it's since peeled off and disappeared.
So the left and right orientation of the rim in its original state must be preserved in the rebuild.
That's why I marked it with tape before disassembling—"original right side goes here."
But that aside, this rim has a different problem.
This rim is a reverse rim.
Using the valve hole as reference, rims where the spoke hole offset matches
what you see on the vast majority of rims in the world I call normal rims,
and rims with the mirror-image offset I call reverse rims.
For some reason, Campagnolo and Fulcrum radial-laced fronts
are almost always reverse rims.
I checked what we have in the shop and found that
Bora WTO rim brake fronts are also reverse rims.
Separate from the valve area, I marked tape on four rim hole locations—two on each side.
Now I'll examine the hole offset, starting from the left in the previous image.
There's a seam-like line down the center from the molding process, but
that rim hole is clearly offset upward from that line.
I drew in an arrow showing hole offset direction.
The reason the hole looks black in the previous image is I had the rim pressed against a wall,
but from here on I'm holding it a bit back.
Here's the next one.
Clearly offset downward.
Next, crossing the valve hole
Also clearly offset upward.
And finally, the fourth one.
Also downward.
The apparent offset amount relative to the centerline isn't perfectly identical
(that's a rim precision issue), but there weren't any holes that looked so centered
that I couldn't tell which direction they were offset.
So this rim is definitely a reverse rim.
And it was originally built as if it were a normal rim.
Separate from the valve area, I'll mark tape on each individual hole
based on which direction it "clearly looks offset to,"
without any preconception that holes must alternate left-right.
For this hole,
it's like this.
For this hole,
it's like this.
This results in tape marks on alternating left and right again,
and this connects consistently with the offset notes from the valve area.
So what's the problem with a reverse rim? For this job, it's that
DT's forced left-right tangent lacing straight-spoke hub is designed for normal rims.
When you look at a normal-offset wheel from the side,
of the left-right pair of spokes at the final cross (four spokes total),
the final cross closer to you appears to progress clockwise.
Reverse rims are the opposite.
With bent spokes and generic bent-spoke hubs, you can create
reverse-rim final cross left-right pairs by switching which way you lay the spoke in initially—
right-drop or left-drop—but a straight-spoke hub designed for normal rims
doesn't give you that flexibility.
This is the 180 hub viewed from the right side.
For work reasons, I threaded all the spokes from the left flange in the outpoke direction first,
but ignore five of them that aren't relevant here.
This is what the final cross pair looks like for a normal rim.
Following the rim's hole offset pattern, I decided to build this wheel
with a normal-rim hub and a reverse rim.
The spoke marked with tape in this image comes from
the lower flange in the image, but
it matches the hole offset. Or rather, I matched it.
Technical archive
A customer brought in an ITLAB45 wheel for work.
Today I'm only touching the front wheel though.
DT180 straight spoke hub, 24H
Pillar brand custom titanium spokes, built with forced left-right 2-cross lacing
with all final crosses on both wheels built from both sides.
The reason this wheel came in was
that the nipples kept coming loose.
It was apparently sent to ITLAB once for repair,
but it started loosening again after that.
The wheel came with an instruction manual full of dubious nonsense,
but before reading that, from what the customer told me,
the wheel's initial state had slack tension,
and when it came back it was pulled tight as a drum.
I don't necessarily object to building wheels with lower spoke tension
if there are compelling reasons informed by weighing all factors
that make it the best choice,
but building a wheel with low tension that doesn't loosen easily
is genuinely difficult work.
If the person who built this wheel had some clear policy or philosophy
about deliberately building with lower tension, that itself isn't something I'd dispute,
but the fact that the customer could feel a huge difference in tension
between before sending it out and after getting it back—
that means there's no consistency in spoke tension.
If you're going to pull it tight, pull it tight from the start, you know?
That's what I was thinking before I even read the manual.
I did tell the customer "why not send it back to ITLAB?"
but they were concerned it would just happen again if the same place looked at it,
so we decided to have our shop handle it.
In the end, I was able to identify what was causing the loosening.
But reading the manual,
it says not to tension the spokes above 110 kgf.
The "reference" spoke tension is given as
100–105 kgf for both the brake side of the front wheel and the drive side of the rear wheel.
The phrasing "reference spoke tension" rather than specified, recommended, or maximum,
and the distinction between "brake side" and "drive side" is verbatim from the original manual, just so you know.
No, this doesn't make sense.
The customer definitely felt a clear difference in tension before and after sending it in,
but was the pre-send state 100 kgf and the returned state 105 kgf?
There's no way a 5 kgf difference would be noticeable enough to be that obvious, which is one thing.
The other thing is: no matter how precise your rim and low-tolerance your spokes are,
no matter how tight you chase runout when building a wheel,
it's impossible to keep spoke tension variation on one side of a wheel
within 5 kgf using materials that exist in reality.
For example, say you build a 24H wheel with the high-tension side bottom at 105 kgf
(of course, with radial and lateral runout chased down and center perfectly true—that's a baseline assumption).
Then several of the 12 spokes on that side will exceed 110 kgf.
So if you're going to build without ever exceeding 110 kgf,
your only option is to set the ceiling at 105 kgf for the wheel build.
But then several of those 12 spokes on one side will drop below 100 kgf.
That's just unavoidable.
If the returned wheel's high-tension side doesn't exceed 110 kgf on a single spoke,
then there's no way the original wheel was built at 100–105 kgf.
Also, the manual says you can measure this wheel's spoke tension with a DT tension meter,
but not with Park Tool's TM-1 or Hozan. That's wrong.
For this job, I'm disassembling the wheel and rebuilding it
with the same pre-delivery tension but with the nipples less prone to loosening,
and I took the maximum H1ST reading from the 12 high-tension spokes,
then used that as reference for rebuilding—so a Hozan tension meter
can build this wheel just fine.
I did use the DT tension meter since it was specified,
but when I measured both D1ST and H1ST against a given second ST (spoke tension in the conventional sense),
the Hozan didn't detect any values that deviated from its normal parabolic curve of first ST vs. second ST—which is what you'd expect.
Actually, through this work I created a conversion chart from D1ST to second ST to H1ST,
so now with Hozan's tension meter I can build wheels with these same spokes going forward.
The Park Tool TM-1 has issues with unit-to-unit variation and the fact that reducing friction in the sliding parts (including lubrication)
makes the needle go up more easily, but as long as you're careful to use one unit consistently under similar conditions,
it's practically fine.
Since DT and Hozan tension meters are extremely expensive,
the TM-1's value is huge for hobby-level wheel building where that's out of reach.
I loosened the nipples.
These nipples turn from the outside,
and the manual says never grab the inside.
I agree with that. I wouldn't do it anyway.
These nipples have abnormally deep thread pockets—
when you press a spoke in without turning it,
the spoke threads are nearly hidden by how deep the pocket is.
A brittle locking compound was used,
but this only prevents initial loosening and doesn't really increase
friction resistance in the threaded area itself.
In fact, after the contact pressure between the nipple and rim let off,
it turned very easily.
There's another reason for that (more on this later).
↑That beast
With deep thread pockets, the brittle compound residue is long too.
I should have mentioned this earlier, but the pre-work state had
a centering error about the thickness of one sheet of paper.
Depending on the centering gauge, it would get a perfect reading,
so I'd say the center was true.
I recorded all D1ST and H1ST values from the high-tension side before work.
I'm careful to note that spoke tension barely changed before and after work.
There was also tape marking where loosening occurred, on a rear wheel spoke,
but knowing that, I worked on the front wheel first.
Since I know the H1ST on the high-tension side of the front wheel,
I could now build the rear wheel to reference tension
even if the hub, rim, and spokes came to me as loose components.
The most dangerous thing about this wheel is
that they applied generous anti-seize compound to the spoke threads
because they're titanium spokes.
Of course that's going to loosen. There's no way it won't.
This is the cause of loosening I mentioned at the start,
and why the nipples turned so easily after I removed that brittle locking agent earlier.
Maybe the person who built this wheel will claim there's no causal relationship
between applying grease to the threads and nipple loosening,
but given that this wheel has a solid track record of loosening even after being reworked
(whether they rebuilt it completely or just re-tensioned without disassembling, who knows),
any claim like that would have zero credibility.
With brittle locking compound on the spokes,
you can't pull the spokes out of the hub flanges.
Anti-seize compound ended up on the hub flange area,
but I cleaned that off later.
↑12 spokes from one side
I tilted a stainless steel pan and sprayed parts cleaner along one edge.
The particulates in the grease convected and swirled around.
I call this a shortcut, but the left and right spokes were the same length.
I did separate them into original-right and original-left,
but given how expensive these spokes are per unit (though still only about 6 times the cost of CX-RAY),
maybe they wanted to reduce the variety of spare spoke inventory.
Feel free to make excuses after the fact—like "disc brake fronts with this little offset
are fine with the same length!" I don't care.
It just tells me the builder had that level of understanding about spoke length
when they were building the wheel.
The 12 original-right spokes weighed 33.3g, and
the 12 original-left spokes were 33.4g.
All 24 came to 66.7g.
The spoke length was 275mm, so spoke specific gravity is
66.7 (g) ÷ 275 (mm) ÷ 24 (spokes) = 0.010106...,
and dividing that by a 100% reference value of 0.0257 gives
0.0393... = 39.3%.
Straight spokes lack the necked-down portion that bent spokes have
in the spoke length measurement but include in the weight,
so spoke specific gravity tends to come out slightly low.
For estimation purposes, 40% is fine.
On some of the original-right spokes (non-rotor side, low-tension side),
there were wear marks from rubbing at the final cross.
I also cleaned the nipples.
The image above isn't the nipples soaking in the parts cleaner I used on the spokes—
it's fresh cleaner sprayed after washing the pan,
so all the grime shown is purely from the nipples.
↑Like this when you tilt the pan and drip cleaner along an edge
Parts cleaner is just preliminary cleaning.
I also ran them through ultrasonic cleaning.
The image above shows the nipples submerged.
Right after I hit the switch, black hazy grime poured from the nipple holes,
but I couldn't capture that on camera.
This rim doesn't look like an offset rim.
Even if it's not an offset rim, there's a possibility that there was once a sticker
saying something like "orient this side toward the disc rotor mount on disc-brake fronts
and toward the freewheel body on the rear,"
and it's since peeled off and disappeared.
So the left and right orientation of the rim in its original state must be preserved in the rebuild.
That's why I marked it with tape before disassembling—"original right side goes here."
But that aside, this rim has a different problem.
This rim is a reverse rim.
Using the valve hole as reference, rims where the spoke hole offset matches
what you see on the vast majority of rims in the world I call normal rims,
and rims with the mirror-image offset I call reverse rims.
For some reason, Campagnolo and Fulcrum radial-laced fronts
are almost always reverse rims.
I checked what we have in the shop and found that
Bora WTO rim brake fronts are also reverse rims.
Separate from the valve area, I marked tape on four rim hole locations—two on each side.
Now I'll examine the hole offset, starting from the left in the previous image.
There's a seam-like line down the center from the molding process, but
that rim hole is clearly offset upward from that line.
I drew in an arrow showing hole offset direction.
The reason the hole looks black in the previous image is I had the rim pressed against a wall,
but from here on I'm holding it a bit back.
Here's the next one.
Clearly offset downward.
Next, crossing the valve hole
Also clearly offset upward.
And finally, the fourth one.
Also downward.
The apparent offset amount relative to the centerline isn't perfectly identical
(that's a rim precision issue), but there weren't any holes that looked so centered
that I couldn't tell which direction they were offset.
So this rim is definitely a reverse rim.
And it was originally built as if it were a normal rim.
Separate from the valve area, I'll mark tape on each individual hole
based on which direction it "clearly looks offset to,"
without any preconception that holes must alternate left-right.
For this hole,
it's like this.
For this hole,
it's like this.
This results in tape marks on alternating left and right again,
and this connects consistently with the offset notes from the valve area.
So what's the problem with a reverse rim? For this job, it's that
DT's forced left-right tangent lacing straight-spoke hub is designed for normal rims.
When you look at a normal-offset wheel from the side,
of the left-right pair of spokes at the final cross (four spokes total),
the final cross closer to you appears to progress clockwise.
Reverse rims are the opposite.
With bent spokes and generic bent-spoke hubs, you can create
reverse-rim final cross left-right pairs by switching which way you lay the spoke in initially—
right-drop or left-drop—but a straight-spoke hub designed for normal rims
doesn't give you that flexibility.
This is the 180 hub viewed from the right side.
For work reasons, I threaded all the spokes from the left flange in the outpoke direction first,
but ignore five of them that aren't relevant here.
This is what the final cross pair looks like for a normal rim.
Following the rim's hole offset pattern, I decided to build this wheel
with a normal-rim hub and a reverse rim.
The spoke marked with tape in this image comes from
the lower flange in the image, but
it matches the hole offset. Or rather, I matched it.
Technical archive
Products Mentioned in This Article
- 🛒 DT180 straight spoke bicycle hub
- 🛒 Pillar titanium bladed spokes
- 🛒 DT Swiss spoke tension meter
- 🛒 Hozan spoke tension meter
* Amazon affiliate links — prices may vary
Original Japanese post: のむラボ日記 #6452