The whiteboard is getting a lot of use. Really glad I bought it.
Today I'm going to talk about the weight per millimeter of spokes.
That said, this isn't really accurate terminology. To be precise,
it's "the weight when an X mm spoke is divided into X segments from the center of the spoke."
I'm just calling that the weight per millimeter.
I'm sure you're thinking "what's this guy going on about?" but I'll explain slowly below.
↑This is a spoke. Please bear with me as I explain using these pretty childish drawings (laugh).
On sports bikes, spoke thickness is basically limited to these two types.
2.0 mm diameter and 1.8 mm diameter.
The thickness of a spoke is called its gauge, and
2.0 mm is also called 14 gauge, and 1.8 mm is called 15 gauge.
There are exceptions—for example, Cosmic Carbon (special proprietary wheel) uses 2.34 mm (13 gauge) spokes—
but basically it comes down to these two types: 2.0 or 1.8.
Since 1.8 is thinner, naturally 1.8 spokes are lighter in weight.
When generic standard spokes like those above are used in off-the-shelf wheelsets,
they're almost 100% of the time 2.0 mm spokes.
Even with LEW VT-1 rim wheelsets that come in under 1000g for a pair,
they use 2.0 mm spokes.
The spokes I normally use for hand-built wheels are also primarily 2.0.
There's a reason for this (I'll explain later).
Nipples also come in 2.0 and 1.8 versions, and they're not interchangeable.
The material is either brass or aluminum. Aluminum is lighter,
but when generic nipples are used on off-the-shelf wheelsets, they're almost 100% brass.
FFWD wheels use generic nipples, so they're brass.
(When custom nipples are used on off-the-shelf wheelsets, they're often aluminum.)
When people say "a spoke broke," it's almost always a break at the neck (the red line in the diagram above).
1.8 spokes have a neck that's also 1.8 mm, so compared to 2.0 spokes,
the risk of breakage in this area is higher.
This is why 1.8 isn't used on off-the-shelf wheelsets,
and why I don't use it much either.
If you build a rear wheel with 1.8, you'll really notice it. The neck clearly fails more easily than with 2.0.
In cases where the nipple is the problem, breakage can occur at the red line portion in the diagram above.
This happens not just with aluminum, but sometimes with brass as well.
Spoke breakage is almost 100% of the time a neck break. They don't break in the middle.
Sometimes a chain can fall to the inside of the low gear and jam with a spoke, causing the spoke to be abraded as if it were reversed inside out, resulting in it breaking in the middle,
but excluding those kinds of external causes, you can say "spoke break = neck break."
So to reduce weight, spokes were developed that keep the neck and threaded portions at 2.0 mm but thin out the middle section. Since breaks almost never happen in the middle,
you can reduce weight without increasing the risk of spoke neck breaks.
Spokes that maintain the same diameter from end to end are called "plain spokes,"
and spokes that thin out in the middle are called "butted spokes."
DT, a Swiss spoke manufacturer, sells plain spokes under the product name Champion
and butted spokes under the name Competition.
In the case of Competition 2.0, the butted portion is 1.8.
Not shown in the diagram above, but with Competition 1.8,
the butted portion is 1.6.
I'll denote Champion 2.0 as 2.0.
I'll denote Competition 2.0 as 2.0–1.8–2.0.
That's just listing the diameters of the neck, butted portion, and threaded portion.
DT also has an even lighter butted spoke model called Revolution.
There are 2.0 and 1.8 versions, but in both the butted portion is 1.5.
Since the butted portion is proportionally longer than in Competition,
it ends up even lighter.
I'll denote Revolution 2.0 as 2.0–1.5–2.0.
The spokes I use most often are DT Champion and Competition, but
there's another spoke I use frequently: the CX-RAY from Sapim (Belgian spoke maker).
This is a spoke with a flattened butted section—
an aero spoke as it's called.
The aero section has a cross-section of 0.9 mm at its most flattened point
and 2.3 mm at its widest point.
This shape is primarily for aerodynamic characteristics, but with the CX-RAY,
the design also incorporates weight reduction.
I'll denote this as 2.0–(0.9–2.3)–2.0.
Sapim does have a 1.8 plain spoke in their lineup,
but none of their butted or aero spoke models come in 1.8 mm diameter.
So there's no 1.8 version of the CX-RAY.
(Though there might be as a custom order.)
Now here's the main topic.
I want to find the weight per millimeter of spokes, but
for example, if divided into 10 equal segments as in the diagram above, A and B would have different weights.
So, as a thought experiment, let's say we divide radially from the center of the spoke.
In the diagram above that would be 5 divisions, but it doesn't look like 5 at all because I'm terrible at drawing,
so just imagine it divided this way.
Now consider a 200 mm spoke divided into 200 segments
and a 300 mm spoke divided into 300 segments, looking at one piece each.
Also consider a case where an X mm spoke is divided into X segments.
The central angle per piece is as shown in the diagram.
What I'm trying to say is:
"The weight of each of these pieces should be roughly the same."
That said, with plain spokes it might be somewhat understandable, but with butted spokes,
the proportion of the butted portion to the overall spoke length varies with spoke length,
so it doesn't really seem like they'd be the same.
A 50 mm Revolution versus a 100 million mm Revolution—
if you divide the weight by the length, naturally the longer one would be lighter.
But changing the subject, I've built many "improperly modified off-the-shelf wheelsets" in the past.
I can't write too openly about a lot of these things, but
I'll leak them out gradually on this blog (laugh), and one of them is
"Cosmic Carbon 80 hand-built with a standard hub,"
and this one has a spoke length of—I won't go into details—about 230 mm.
Unless you're doing something like ××(self-censored) to a Campagnolo Bullet 105,
there probably aren't many shorter spokes than this for 700C wheels.
↑This is the front wheel of my cyclocross bike, built as a Molanbon laced Openpro 32H.
The longest spokes for 700C would probably be when you take "an old tubular rim with lower rim height, 36H, built as 8-spoke Molanbon lacing,"
and in that case it would be around 310 mm (well, I do know the exact measurement).
So that means the spoke lengths that can exist on a road bike
basically fall entirely within the range of 230 mm to 310 mm.
The weight variation caused by butted processing would be very limited.
So I actually did the research. I'm only showing three types, but I actually have many more samples.
Weighing just a single spoke on a scale that can only measure in 1g or 0.1g increments
is far too rough. In the cases shown above, they all happen to be 32 spokes, but
if you weigh a decent quantity of spokes of the same length and divide by the number,
you get a pretty accurate weight per spoke.
And here's what I got.
Then I divide further by the length.
I wrote it as weight per millimeter, but as mentioned at the beginning,
strictly speaking it's the weight of one piece from the radial division.
Since I'm dividing by length, I'm calling it per millimeter.
I think these can be considered pretty much the same.
I also tried this with Sapim's CX-RAY.
The total weight looks like this,
and the per-spoke weight looks like this.
Then I divided by the length. There is some variation.
The maximum variation is 0.004g per 1000mm of spoke.
I have more samples, but this was the largest variation I found.
I also tried it with DT Champion 2.0 plain spokes.
Sapim has a 2.0 plain spoke model called Leader.
Hoshi Industries (Japanese spoke maker) has a 2.0 plain model called Starbright.
These are not strictly stainless steel spokes. They are stainless,
but it's a bit different from the general image of stainless steel.
Writing about that would make this even longer, so I'll do that another day.
DT, Sapim, Hoshi, and other manufacturers surely don't use exactly the same additives or ratios in their spokes,
so even with 2.0 mm plain spokes, if you examine a large enough sample,
you'd probably see differences in density.
Anyway, I'm going to set DT Champion 2.0 at 0.0257g per millimeter as my 100% baseline
and calculate the weight ratio of each spoke.
The reason this diagram still exists is because my whiteboard is double-sided.
I really am glad I bought it.
↑Here's how it breaks down. For the variation, I'm using the median value.
↑I also added Champion 1.8.
I forgot to thread-cut it (laugh).
Naturally it's lighter than Competition 2.0–1.8–2.0.
Revolution 2.0 and CX-RAY, compared to plain 2.0, have
about two-thirds of the material removed. Amazing.
Now I can calculate spoke weight factoring in length too.
I'm doing three multiplications so there might be some error margin, but
as a Fermi estimation method, it's pretty accurate.
Plug in the percentage in red from above as the final coefficient.
Using this, you can get a rough idea of the weight before ordering spokes
or before building a wheel (though you need to know the coefficient).
Also, though I haven't written it here, there are two spokes in the world with coefficients under 60%.
If you really want to build a super-light spoke wheel, using those becomes essential.
I'll also note the nipple weight.
Now I can get rough estimates of the weight of spokes and nipples, the wheel's key components.
For hubs and rims, measuring the actual parts is best, but if you don't have them,
you can calculate using catalog weight.
In almost all cases the actual weight will be more than the catalog weight, so the figure from your desktop calculation
serves as a good ballpark—"it should be around this, but it'll probably end up heavier."
If you weigh your bundle of spokes each time you build a wheel,
you'll get data to develop more accurate coefficients.
This kind of accumulation of data is what matters.
Today I'm going to talk about the weight per millimeter of spokes.
That said, this isn't really accurate terminology. To be precise,
it's "the weight when an X mm spoke is divided into X segments from the center of the spoke."
I'm just calling that the weight per millimeter.
I'm sure you're thinking "what's this guy going on about?" but I'll explain slowly below.
↑This is a spoke. Please bear with me as I explain using these pretty childish drawings (laugh).
On sports bikes, spoke thickness is basically limited to these two types.
2.0 mm diameter and 1.8 mm diameter.
The thickness of a spoke is called its gauge, and
2.0 mm is also called 14 gauge, and 1.8 mm is called 15 gauge.
There are exceptions—for example, Cosmic Carbon (special proprietary wheel) uses 2.34 mm (13 gauge) spokes—
but basically it comes down to these two types: 2.0 or 1.8.
Since 1.8 is thinner, naturally 1.8 spokes are lighter in weight.
When generic standard spokes like those above are used in off-the-shelf wheelsets,
they're almost 100% of the time 2.0 mm spokes.
Even with LEW VT-1 rim wheelsets that come in under 1000g for a pair,
they use 2.0 mm spokes.
The spokes I normally use for hand-built wheels are also primarily 2.0.
There's a reason for this (I'll explain later).
Nipples also come in 2.0 and 1.8 versions, and they're not interchangeable.
The material is either brass or aluminum. Aluminum is lighter,
but when generic nipples are used on off-the-shelf wheelsets, they're almost 100% brass.
FFWD wheels use generic nipples, so they're brass.
(When custom nipples are used on off-the-shelf wheelsets, they're often aluminum.)
When people say "a spoke broke," it's almost always a break at the neck (the red line in the diagram above).
1.8 spokes have a neck that's also 1.8 mm, so compared to 2.0 spokes,
the risk of breakage in this area is higher.
This is why 1.8 isn't used on off-the-shelf wheelsets,
and why I don't use it much either.
If you build a rear wheel with 1.8, you'll really notice it. The neck clearly fails more easily than with 2.0.
In cases where the nipple is the problem, breakage can occur at the red line portion in the diagram above.
This happens not just with aluminum, but sometimes with brass as well.
Spoke breakage is almost 100% of the time a neck break. They don't break in the middle.
Sometimes a chain can fall to the inside of the low gear and jam with a spoke, causing the spoke to be abraded as if it were reversed inside out, resulting in it breaking in the middle,
but excluding those kinds of external causes, you can say "spoke break = neck break."
So to reduce weight, spokes were developed that keep the neck and threaded portions at 2.0 mm but thin out the middle section. Since breaks almost never happen in the middle,
you can reduce weight without increasing the risk of spoke neck breaks.
Spokes that maintain the same diameter from end to end are called "plain spokes,"
and spokes that thin out in the middle are called "butted spokes."
DT, a Swiss spoke manufacturer, sells plain spokes under the product name Champion
and butted spokes under the name Competition.
In the case of Competition 2.0, the butted portion is 1.8.
Not shown in the diagram above, but with Competition 1.8,
the butted portion is 1.6.
I'll denote Champion 2.0 as 2.0.
I'll denote Competition 2.0 as 2.0–1.8–2.0.
That's just listing the diameters of the neck, butted portion, and threaded portion.
DT also has an even lighter butted spoke model called Revolution.
There are 2.0 and 1.8 versions, but in both the butted portion is 1.5.
Since the butted portion is proportionally longer than in Competition,
it ends up even lighter.
I'll denote Revolution 2.0 as 2.0–1.5–2.0.
The spokes I use most often are DT Champion and Competition, but
there's another spoke I use frequently: the CX-RAY from Sapim (Belgian spoke maker).
This is a spoke with a flattened butted section—
an aero spoke as it's called.
The aero section has a cross-section of 0.9 mm at its most flattened point
and 2.3 mm at its widest point.
This shape is primarily for aerodynamic characteristics, but with the CX-RAY,
the design also incorporates weight reduction.
I'll denote this as 2.0–(0.9–2.3)–2.0.
Sapim does have a 1.8 plain spoke in their lineup,
but none of their butted or aero spoke models come in 1.8 mm diameter.
So there's no 1.8 version of the CX-RAY.
(Though there might be as a custom order.)
Now here's the main topic.
I want to find the weight per millimeter of spokes, but
for example, if divided into 10 equal segments as in the diagram above, A and B would have different weights.
So, as a thought experiment, let's say we divide radially from the center of the spoke.
In the diagram above that would be 5 divisions, but it doesn't look like 5 at all because I'm terrible at drawing,
so just imagine it divided this way.
Now consider a 200 mm spoke divided into 200 segments
and a 300 mm spoke divided into 300 segments, looking at one piece each.
Also consider a case where an X mm spoke is divided into X segments.
The central angle per piece is as shown in the diagram.
What I'm trying to say is:
"The weight of each of these pieces should be roughly the same."
That said, with plain spokes it might be somewhat understandable, but with butted spokes,
the proportion of the butted portion to the overall spoke length varies with spoke length,
so it doesn't really seem like they'd be the same.
A 50 mm Revolution versus a 100 million mm Revolution—
if you divide the weight by the length, naturally the longer one would be lighter.
But changing the subject, I've built many "improperly modified off-the-shelf wheelsets" in the past.
I can't write too openly about a lot of these things, but
I'll leak them out gradually on this blog (laugh), and one of them is
"Cosmic Carbon 80 hand-built with a standard hub,"
and this one has a spoke length of—I won't go into details—about 230 mm.
Unless you're doing something like ××(self-censored) to a Campagnolo Bullet 105,
there probably aren't many shorter spokes than this for 700C wheels.
↑This is the front wheel of my cyclocross bike, built as a Molanbon laced Openpro 32H.
The longest spokes for 700C would probably be when you take "an old tubular rim with lower rim height, 36H, built as 8-spoke Molanbon lacing,"
and in that case it would be around 310 mm (well, I do know the exact measurement).
So that means the spoke lengths that can exist on a road bike
basically fall entirely within the range of 230 mm to 310 mm.
The weight variation caused by butted processing would be very limited.
So I actually did the research. I'm only showing three types, but I actually have many more samples.
Weighing just a single spoke on a scale that can only measure in 1g or 0.1g increments
is far too rough. In the cases shown above, they all happen to be 32 spokes, but
if you weigh a decent quantity of spokes of the same length and divide by the number,
you get a pretty accurate weight per spoke.
And here's what I got.
Then I divide further by the length.
I wrote it as weight per millimeter, but as mentioned at the beginning,
strictly speaking it's the weight of one piece from the radial division.
Since I'm dividing by length, I'm calling it per millimeter.
I think these can be considered pretty much the same.
I also tried this with Sapim's CX-RAY.
The total weight looks like this,
and the per-spoke weight looks like this.
Then I divided by the length. There is some variation.
The maximum variation is 0.004g per 1000mm of spoke.
I have more samples, but this was the largest variation I found.
I also tried it with DT Champion 2.0 plain spokes.
Sapim has a 2.0 plain spoke model called Leader.
Hoshi Industries (Japanese spoke maker) has a 2.0 plain model called Starbright.
These are not strictly stainless steel spokes. They are stainless,
but it's a bit different from the general image of stainless steel.
Writing about that would make this even longer, so I'll do that another day.
DT, Sapim, Hoshi, and other manufacturers surely don't use exactly the same additives or ratios in their spokes,
so even with 2.0 mm plain spokes, if you examine a large enough sample,
you'd probably see differences in density.
Anyway, I'm going to set DT Champion 2.0 at 0.0257g per millimeter as my 100% baseline
and calculate the weight ratio of each spoke.
The reason this diagram still exists is because my whiteboard is double-sided.
I really am glad I bought it.
↑Here's how it breaks down. For the variation, I'm using the median value.
↑I also added Champion 1.8.
I forgot to thread-cut it (laugh).
Naturally it's lighter than Competition 2.0–1.8–2.0.
Revolution 2.0 and CX-RAY, compared to plain 2.0, have
about two-thirds of the material removed. Amazing.
Now I can calculate spoke weight factoring in length too.
I'm doing three multiplications so there might be some error margin, but
as a Fermi estimation method, it's pretty accurate.
Plug in the percentage in red from above as the final coefficient.
Using this, you can get a rough idea of the weight before ordering spokes
or before building a wheel (though you need to know the coefficient).
Also, though I haven't written it here, there are two spokes in the world with coefficients under 60%.
If you really want to build a super-light spoke wheel, using those becomes essential.
I'll also note the nipple weight.
Now I can get rough estimates of the weight of spokes and nipples, the wheel's key components.
For hubs and rims, measuring the actual parts is best, but if you don't have them,
you can calculate using catalog weight.
In almost all cases the actual weight will be more than the catalog weight, so the figure from your desktop calculation
serves as a good ballpark—"it should be around this, but it'll probably end up heavier."
If you weigh your bundle of spokes each time you build a wheel,
you'll get data to develop more accurate coefficients.
This kind of accumulation of data is what matters.