Edit: There is a correction regarding the content of this article.
I verified it based on comments I received (→here) so please check that article as well.
I considered writing this in my previous post,
but it seemed better to split it into its own article.
The wheel I just rebuilt is probably using Sapim red nipples.
The reason is that the length was 14mm,
and while DT does make 14mm aluminum nipples,
they're not in stable supply.
Also, the red anodize was quite dark, which is another clue.
DT's red nipples these days are somewhat lighter in shade.
Standard universal nipples are normally 12mm,
and what are called long nipples are 16mm,
but the silver aluminum nipples that come with Sapim CX-RAY are 14mm.
（Sapim aluminum nipples are available in 12mm if purchased separately）
"If you use long nipples, you can use shorter spokes"
—some people misunderstand this, but it's not true. They're the same length.
That's what this post is about.
If I roughly sketch a 12mm nipple, it looks like this.
When you insert the spoke into it from the inner rim side of the finished wheel,
there's a section without threads before it hits the threaded portion.
This is roughly about 4mm, and I call it the periodontal pocket.
On the outer side, there's a slot for a flat-head screwdriver,
and this slot is roughly about 1mm deep.
So subtracting that, about 7mm becomes the threaded portion.
In my spoke length calculation formula,
I calculate the length so that the spoke end is flush with the outer rim side edge of the nipple.
At this point, the spoke's threaded end
doesn't quite reach the nipple's thread start.
If you accidentally use a spoke that's too long,
the spoke end will protrude from the nipple
and use up all the threads.
From the flush position, tightening further
gives you roughly 2mm or less before the threads bottom out.
Using the wheel with the threads fully bottomed out
creates extremely high risk of spoke breakage at the boundary of the spoke's thread end.
You also can't adjust spoke tension for trueing.
Spoke length is determined by hub and rim dimensions, and how the wheel is laced,
and that length is calculated to the outer rim side edge of the nipple,
so if the nipple thread start position varied depending on nipple length,
it would actually be inconvenient.
So, nipples longer than 12mm simply have a deeper periodontal pocket,
and the nipple's thread start is approximately 8mm from the outer edge
regardless of the nipple's overall length.
So why do long nipples exist?
Because there are rims where it would be problematic not to have them.
On Mavic CXP30 rims or first-generation Cosmic Elite rims (←actually the same except for hole count)
the nipple neck seating area is positioned slightly toward the inner side,
and without long nipples you can't get a tool in.
Also, on Honfu carbon rims and similar, to ensure strength apparently,
the inner side is made quite thick,
and with 12mm nipples the four-sided gripping area for the tool
barely protrudes, so 14mm nipples might be better in those cases.
However, nipples with deep periodontal pockets have lower resistance to overtightening during adjustment,
so without special reason, I currently use only 12mm nipples.
The 14mm aluminum nipples that come with Sapim CX-RAY
—I don't use those either, so quite a few have piled up.
↑This is a photo from before rebuilding the wheel in my previous post,
and though there was a brittle type of threadlock that prevents initial loosening
and becomes nearly ineffective once the nipple is turned again,
it had hardened like plaque,
so I could clearly see the periodontal pocket—and that motivated me to write this post.
Since I don't use this type of threadlock, I normally never see this.
I verified it based on comments I received (→here) so please check that article as well.
I considered writing this in my previous post,
but it seemed better to split it into its own article.
The wheel I just rebuilt is probably using Sapim red nipples.
The reason is that the length was 14mm,
and while DT does make 14mm aluminum nipples,
they're not in stable supply.
Also, the red anodize was quite dark, which is another clue.
DT's red nipples these days are somewhat lighter in shade.
Standard universal nipples are normally 12mm,
and what are called long nipples are 16mm,
but the silver aluminum nipples that come with Sapim CX-RAY are 14mm.
（Sapim aluminum nipples are available in 12mm if purchased separately）
"If you use long nipples, you can use shorter spokes"
—some people misunderstand this, but it's not true. They're the same length.
That's what this post is about.
If I roughly sketch a 12mm nipple, it looks like this.
When you insert the spoke into it from the inner rim side of the finished wheel,
there's a section without threads before it hits the threaded portion.
This is roughly about 4mm, and I call it the periodontal pocket.
On the outer side, there's a slot for a flat-head screwdriver,
and this slot is roughly about 1mm deep.
So subtracting that, about 7mm becomes the threaded portion.
In my spoke length calculation formula,
I calculate the length so that the spoke end is flush with the outer rim side edge of the nipple.
At this point, the spoke's threaded end
doesn't quite reach the nipple's thread start.
If you accidentally use a spoke that's too long,
the spoke end will protrude from the nipple
and use up all the threads.
From the flush position, tightening further
gives you roughly 2mm or less before the threads bottom out.
Using the wheel with the threads fully bottomed out
creates extremely high risk of spoke breakage at the boundary of the spoke's thread end.
You also can't adjust spoke tension for trueing.
Spoke length is determined by hub and rim dimensions, and how the wheel is laced,
and that length is calculated to the outer rim side edge of the nipple,
so if the nipple thread start position varied depending on nipple length,
it would actually be inconvenient.
So, nipples longer than 12mm simply have a deeper periodontal pocket,
and the nipple's thread start is approximately 8mm from the outer edge
regardless of the nipple's overall length.
So why do long nipples exist?
Because there are rims where it would be problematic not to have them.
On Mavic CXP30 rims or first-generation Cosmic Elite rims (←actually the same except for hole count)
the nipple neck seating area is positioned slightly toward the inner side,
and without long nipples you can't get a tool in.
Also, on Honfu carbon rims and similar, to ensure strength apparently,
the inner side is made quite thick,
and with 12mm nipples the four-sided gripping area for the tool
barely protrudes, so 14mm nipples might be better in those cases.
However, nipples with deep periodontal pockets have lower resistance to overtightening during adjustment,
so without special reason, I currently use only 12mm nipples.
The 14mm aluminum nipples that come with Sapim CX-RAY
—I don't use those either, so quite a few have piled up.
↑This is a photo from before rebuilding the wheel in my previous post,
and though there was a brittle type of threadlock that prevents initial loosening
and becomes nearly ineffective once the nipple is turned again,
it had hardened like plaque,
so I could clearly see the periodontal pocket—and that motivated me to write this post.
Since I don't use this type of threadlock, I normally never see this.