The other day, I wrote something like "there's some merit to reverse Italian lacing on the freewheel side," and I got a comment asking "why?" so today I'll write about that.
↑On the left is a ZIPP from a while back, on the right is an FSA hub.
The FSA hub is a regular flanged hub.
In the case of tangent lacing, spokes going in the drive direction and spokes going in the non-drive direction
both come out from the same flange.
I'm going to call this kind of normal hub flange "coaxial flange" from now on.
In contrast, the ZIPP hub has spokes in the drive direction and non-drive direction
coming out from clearly different positions. There's a left-right difference in position.
I'm going to call this kind of hub "offset flange" from now on.
I'm going off on a tangent here.
It's not directly related to today's topic, but while I'm at it.
The flange width I use as the basis for my lateral stiffness calculations
is strictly the width between the positions where spokes begin to emerge.
That's the Xmm (the width between the red lines) in the diagram above.
Normal hub flanges are usually about 3.5mm thick,
If you were to have a front wheel with non-drive-side radial lacing,
and then built a front hub with 7mm narrower flange width using drive-side lacing,
you could argue that despite different flange widths, the lateral stiffness would be the same.
This is actually the basis for why I build almost all of my personal wheels with drive-side lacing,
but because many radial builds in the world use non-drive-side lacing,
I don't push this point strongly myself.
It's also the reason Noma Lab wheels don't fundamentally use it,
but if someone asked me to "please build it with drive-side radial," I wouldn't refuse.
In the case of tangent lacing, drive-side and non-drive-side spokes alternate,
and in this case I consider the center of the flange as the basis for lateral stiffness calculation.
As a side note, spoke length is calculated from the flange outer-to-outer width,
so the calculated spoke length is the drive-side spoke length.
Since the difference is small, I build non-drive-side spokes at that length too.
End of tangent
When you pedal and the rear wheel tire pushes against the ground,
the spokes' job is to transmit the hub's forward twisting power to the rim.
The spokes that mainly do this work are the drive-direction spokes.
This is an excerpt from a Campagnolo video, and they only evaluate
the drive-direction spokes when it comes to force transmission.
The drive-direction spokes hold the key to drivetrain efficiency, but
if you focus only on drivetrain efficiency, the drive-direction spokes
would ideally be closer to the hub center (directly below the rim).
If you apply that to an offset-flange hub,
you'd have drive-direction spokes coming out of the red holes in the diagram above.
↑That's this configuration.
On the offset flange, the drive-direction spokes are positioned
closer to directly below the rim.
But this has the rightmost spoke going in the non-drive direction—
depending on how you look at it, that's reverse Italian lacing.
The old ZIPP is like that too.
The hole machining shape dictates which direction the spokes go through.
This is an Extralight hub, but even though it's an offset flange,
the spokes can go through either way. Smart.
With the old ZIPP, the spokes have to go through this way.
From a coaxial-flange perspective, it's definitely reverse Italian lacing.
But looking at it this way, you can sense the intention to position
drive-direction spokes closer to directly below the rim.
With Colima, the hole positions are barely enough to be called offset flanges, but
the wheels are built in a direction that could be interpreted as Italian lacing (as shown in the image above).
↑Regular hubs (coaxial flanges) in Italian lacing look like this.
Older FSA, or Reynolds RZR, has three-flange hubs.
The image above is an RZR, and the rear wheel has left-right radial lacing.
With spokes and hub flanges locked solid in carbon,
this works.
Looking at the middle flange's position, it's at the hub center—
directly below the rim.
Since it handles drive transmission,
it only has drive-direction spokes.
Just like in the Campagnolo video image earlier,
non-drive-direction spokes are ignored in terms of drivetrain efficiency.
This is just my personal opinion, but
if you go so far as to add a third flange at the hub center,
I can understand positioning drive-direction spokes directly below the rim.
But with Shimano or ZIPP-level offset flanges,
the center-positioned hole on the freewheel side isn't dramatically centered.
Plus, the rightmost spoke is in the non-drive direction and runs
nearly tangentially, so during pedaling with forward-twisting power
I can't shake the image of stress that would pop the spoke out like this.
In reality, with spoke tension, this doesn't happen,
but I hate the fact that it "looks like it might."
The RZR has no non-drive-direction spokes—
it's a thoughtfully designed approach.
Shimano's offset-flange hubs are laced in what amounts to reverse Italian lacing.
The same goes for the freewheel side of the current Optavar
(is it ORIGINAL PATENT BY ROYAL? A curious acronym) wheels.
Back in the 7850 era, I asked about this reverse Italian lacing approach at a Shimano seminar,
and the answer was "we think that's better for our company,"
so okay, you can keep thinking that.
If Optavar was going to copy 2:1 lacing anyway,
they might as well have used a high-low flange.
Though that would just make it look like "Fulcrum Racing Speed
in various rim heights."
The image above is a WH-R500 (coaxial-flange hub),
and it's laced Italian.
With Easton, the offset is about the same as coaxial flanges,
but the lacing is built in a way that reads as reverse Italian.
Since the spokes stand much more upright than tangentially,
it looks better against the "spoke root pullout stress."
Easton's bent-spoke models (coaxial-flange hubs) are also
laced reverse Italian.
Like the PowerTap in-house wheels from before, hand-built wheels
seem to favor reverse Italian lacing.
This is the "there's some merit to reverse Italian lacing" I mentioned at the start,
but I don't think it's correct, so for rear wheels (with rim-side brakes)
I stick exclusively to Italian lacing.
Actually, I've been asked in comments before, "Wouldn't reverse Italian lacing be better for drivetrain efficiency?"
In this article I'm calling normal hubs "coaxial flanges," but
they're still technically offset by the flange thickness of about 3.5mm.
With reverse Italian lacing, drive-direction spokes come about 3.5mm
closer to directly below the rim.
If you focus only on that, reverse Italian lacing does seem appealing,
but considering things like the behavior during hard braking
and having the spokes that get pulled during pedaling closest to the sprocket,
I think Italian lacing is better.
Many manufacturers use straight spokes in what amounts to reverse Italian lacing,
but aside from smaller makers, only Shimano and Easton do.
Mavic, Campagnolo, and Fulcrum use Italian-equivalent lacing.
(That's probably why they don't have the offset-flange design, but)
In my view, even accounting for the merit reverse Italian lacing has,
my conclusion is that reverse Italian lacing is not good.
↑Here's the opening image again.
Even though we call them offset flanges, they're actually the same dimensions as coaxial flanges.
↑On the left is a ZIPP from a while back, on the right is an FSA hub.
The FSA hub is a regular flanged hub.
In the case of tangent lacing, spokes going in the drive direction and spokes going in the non-drive direction
both come out from the same flange.
I'm going to call this kind of normal hub flange "coaxial flange" from now on.
In contrast, the ZIPP hub has spokes in the drive direction and non-drive direction
coming out from clearly different positions. There's a left-right difference in position.
I'm going to call this kind of hub "offset flange" from now on.
I'm going off on a tangent here.
It's not directly related to today's topic, but while I'm at it.
The flange width I use as the basis for my lateral stiffness calculations
is strictly the width between the positions where spokes begin to emerge.
That's the Xmm (the width between the red lines) in the diagram above.
Normal hub flanges are usually about 3.5mm thick,
If you were to have a front wheel with non-drive-side radial lacing,
and then built a front hub with 7mm narrower flange width using drive-side lacing,
you could argue that despite different flange widths, the lateral stiffness would be the same.
This is actually the basis for why I build almost all of my personal wheels with drive-side lacing,
but because many radial builds in the world use non-drive-side lacing,
I don't push this point strongly myself.
It's also the reason Noma Lab wheels don't fundamentally use it,
but if someone asked me to "please build it with drive-side radial," I wouldn't refuse.
In the case of tangent lacing, drive-side and non-drive-side spokes alternate,
and in this case I consider the center of the flange as the basis for lateral stiffness calculation.
As a side note, spoke length is calculated from the flange outer-to-outer width,
so the calculated spoke length is the drive-side spoke length.
Since the difference is small, I build non-drive-side spokes at that length too.
End of tangent
When you pedal and the rear wheel tire pushes against the ground,
the spokes' job is to transmit the hub's forward twisting power to the rim.
The spokes that mainly do this work are the drive-direction spokes.
This is an excerpt from a Campagnolo video, and they only evaluate
the drive-direction spokes when it comes to force transmission.
The drive-direction spokes hold the key to drivetrain efficiency, but
if you focus only on drivetrain efficiency, the drive-direction spokes
would ideally be closer to the hub center (directly below the rim).
If you apply that to an offset-flange hub,
you'd have drive-direction spokes coming out of the red holes in the diagram above.
↑That's this configuration.
On the offset flange, the drive-direction spokes are positioned
closer to directly below the rim.
But this has the rightmost spoke going in the non-drive direction—
depending on how you look at it, that's reverse Italian lacing.
The old ZIPP is like that too.
The hole machining shape dictates which direction the spokes go through.
This is an Extralight hub, but even though it's an offset flange,
the spokes can go through either way. Smart.
With the old ZIPP, the spokes have to go through this way.
From a coaxial-flange perspective, it's definitely reverse Italian lacing.
But looking at it this way, you can sense the intention to position
drive-direction spokes closer to directly below the rim.
With Colima, the hole positions are barely enough to be called offset flanges, but
the wheels are built in a direction that could be interpreted as Italian lacing (as shown in the image above).
↑Regular hubs (coaxial flanges) in Italian lacing look like this.
Older FSA, or Reynolds RZR, has three-flange hubs.
The image above is an RZR, and the rear wheel has left-right radial lacing.
With spokes and hub flanges locked solid in carbon,
this works.
Looking at the middle flange's position, it's at the hub center—
directly below the rim.
Since it handles drive transmission,
it only has drive-direction spokes.
Just like in the Campagnolo video image earlier,
non-drive-direction spokes are ignored in terms of drivetrain efficiency.
This is just my personal opinion, but
if you go so far as to add a third flange at the hub center,
I can understand positioning drive-direction spokes directly below the rim.
But with Shimano or ZIPP-level offset flanges,
the center-positioned hole on the freewheel side isn't dramatically centered.
Plus, the rightmost spoke is in the non-drive direction and runs
nearly tangentially, so during pedaling with forward-twisting power
I can't shake the image of stress that would pop the spoke out like this.
In reality, with spoke tension, this doesn't happen,
but I hate the fact that it "looks like it might."
The RZR has no non-drive-direction spokes—
it's a thoughtfully designed approach.
Shimano's offset-flange hubs are laced in what amounts to reverse Italian lacing.
The same goes for the freewheel side of the current Optavar
(is it ORIGINAL PATENT BY ROYAL? A curious acronym) wheels.
Back in the 7850 era, I asked about this reverse Italian lacing approach at a Shimano seminar,
and the answer was "we think that's better for our company,"
so okay, you can keep thinking that.
If Optavar was going to copy 2:1 lacing anyway,
they might as well have used a high-low flange.
Though that would just make it look like "Fulcrum Racing Speed
in various rim heights."
The image above is a WH-R500 (coaxial-flange hub),
and it's laced Italian.
With Easton, the offset is about the same as coaxial flanges,
but the lacing is built in a way that reads as reverse Italian.
Since the spokes stand much more upright than tangentially,
it looks better against the "spoke root pullout stress."
Easton's bent-spoke models (coaxial-flange hubs) are also
laced reverse Italian.
Like the PowerTap in-house wheels from before, hand-built wheels
seem to favor reverse Italian lacing.
This is the "there's some merit to reverse Italian lacing" I mentioned at the start,
but I don't think it's correct, so for rear wheels (with rim-side brakes)
I stick exclusively to Italian lacing.
Actually, I've been asked in comments before, "Wouldn't reverse Italian lacing be better for drivetrain efficiency?"
In this article I'm calling normal hubs "coaxial flanges," but
they're still technically offset by the flange thickness of about 3.5mm.
With reverse Italian lacing, drive-direction spokes come about 3.5mm
closer to directly below the rim.
If you focus only on that, reverse Italian lacing does seem appealing,
but considering things like the behavior during hard braking
and having the spokes that get pulled during pedaling closest to the sprocket,
I think Italian lacing is better.
Many manufacturers use straight spokes in what amounts to reverse Italian lacing,
but aside from smaller makers, only Shimano and Easton do.
Mavic, Campagnolo, and Fulcrum use Italian-equivalent lacing.
(That's probably why they don't have the offset-flange design, but)
In my view, even accounting for the merit reverse Italian lacing has,
my conclusion is that reverse Italian lacing is not good.
↑Here's the opening image again.
Even though we call them offset flanges, they're actually the same dimensions as coaxial flanges.