Today's work doesn't fall under the "wheel rebuild" category (and so on).
I received a Cosmic Carbon PowerTap (Mavic) hub from a customer.
The hub is an SL+ 20-hole, but
this wasn't some custom build using a leftover rim—
it's an official specification that appeared in the original catalog back then.
When I swapped it over to a Shimano 11-speed freebody that didn't exist back then,
the sprocket interfered with the spokes on the freewheel side,
so the customer brought it in asking me to convert it to reverse spoking
to resolve the issue.
PowerTap hubs fundamentally prohibit radial lacing.
They require a minimum of 1-cross lacing on both drive and non-drive sides,
but apparently if absolutely necessary, radial lacing on the freewheel side alone is just barely acceptable (※).
※This wasn't in the manual as far as I remember,
but the distributor told me about it once.
← this side
this side →
← this side
this side →
The Cosmic Carbon's carbon hood has spoke holes drilled to match
the spoke path when laced tangentially with the original hub.
If you use radial lacing, the spokes will alternately
interfere with the left and right edges of the hood openings.
With radial lacing, the spoke path when viewed from the side of the wheel
is the same regardless of flange diameter, so
even if the flange diameter changes, this problem can't be avoided.
Even when building Cosmic Carbon rims on non-original hubs using four-cross or similar patterns,
spokes can dig into the hood, and
even in the original configuration, there are cases where
spokes just touch the edges of the hood holes without cutting into them.
These holes are pretty roughly made, honestly.
When the Cosmic Carbon SL came out,
the width of the aero spoke's flat section grew slightly,
so the hood holes were enlarged to match, but
this is an earlier model (the rim had a label dated October 2002).
Being official Mavic spec, it uses some pretty unique spokes.
The Cosmic Carbon spokes are flat spokes based on size 13,
so the nipples are also size 13
(and furthermore, they're the internal-type nipples that grip from the hexagonal outer edge on the rim side).
This wheel's spokes are furthermore a bent-head variant of this—
such an unusual spoke that nothing comparable exists as a standard part.
You might find size 13 spokes used on cargo bike wheels or
old utility bikes (like tofu-seller bicycles), but
aero spokes or internal nipples in that size simply don't exist.
In the image above I tried fitting them into size 14 nipples,
but they only go into the circular recess—there's not even one thread engaged.
I weighed 10 spokes from the freewheel side on a scale with 0.1g precision.
Calculating spoke specific weight from just one spoke at 7.2g would be inaccurate,
but weighing 10 spokes on a 0.1g scale gives quite precise results.
These spokes measured 269mm actual length, so
in terms of spoke specific weight: "one 269mm spoke weighs 72.0g"
and the weight per millimeter is 0.026765···g.
The 100% spoke specific weight is defined as
"2.0mm plain spoke, 1mm length weighs 0.025g", so
these spokes have a specific weight of 104.143...%.
So roughly 104% is fair.
They were lighter than I expected.
This is probably because the PowerTap hub flanges don't have
slots cut for flat spokes,
preventing the aero spokes from being made too flat.
Done.
Just a side note: since I didn't completely disassemble the wheel,
it doesn't meet the criteria I arbitrarily set for "wheel rebuild today" (and so on).
↑ The spoke heads don't protrude at all beyond the hub flange, so
there shouldn't be any interference problems.
Similar work I've done includes
converting a Bontrager PowerTap hub wheel to reverse spoking (→here), and
solving an interference problem with Campagnolo 11-speed that didn't exist
when the original R-SYS came out (→here).
With the R-SYS issue, I didn't write about it at the time, but
the flange had thick sidewalls, so
I ground it down to a point where it wouldn't interfere with the sprocket.
I received a Cosmic Carbon PowerTap (Mavic) hub from a customer.
The hub is an SL+ 20-hole, but
this wasn't some custom build using a leftover rim—
it's an official specification that appeared in the original catalog back then.
When I swapped it over to a Shimano 11-speed freebody that didn't exist back then,
the sprocket interfered with the spokes on the freewheel side,
so the customer brought it in asking me to convert it to reverse spoking
to resolve the issue.
PowerTap hubs fundamentally prohibit radial lacing.
They require a minimum of 1-cross lacing on both drive and non-drive sides,
but apparently if absolutely necessary, radial lacing on the freewheel side alone is just barely acceptable (※).
※This wasn't in the manual as far as I remember,
but the distributor told me about it once.
← this side
this side →
← this side
this side →
The Cosmic Carbon's carbon hood has spoke holes drilled to match
the spoke path when laced tangentially with the original hub.
If you use radial lacing, the spokes will alternately
interfere with the left and right edges of the hood openings.
With radial lacing, the spoke path when viewed from the side of the wheel
is the same regardless of flange diameter, so
even if the flange diameter changes, this problem can't be avoided.
Even when building Cosmic Carbon rims on non-original hubs using four-cross or similar patterns,
spokes can dig into the hood, and
even in the original configuration, there are cases where
spokes just touch the edges of the hood holes without cutting into them.
These holes are pretty roughly made, honestly.
When the Cosmic Carbon SL came out,
the width of the aero spoke's flat section grew slightly,
so the hood holes were enlarged to match, but
this is an earlier model (the rim had a label dated October 2002).
Being official Mavic spec, it uses some pretty unique spokes.
The Cosmic Carbon spokes are flat spokes based on size 13,
so the nipples are also size 13
(and furthermore, they're the internal-type nipples that grip from the hexagonal outer edge on the rim side).
This wheel's spokes are furthermore a bent-head variant of this—
such an unusual spoke that nothing comparable exists as a standard part.
You might find size 13 spokes used on cargo bike wheels or
old utility bikes (like tofu-seller bicycles), but
aero spokes or internal nipples in that size simply don't exist.
In the image above I tried fitting them into size 14 nipples,
but they only go into the circular recess—there's not even one thread engaged.
I weighed 10 spokes from the freewheel side on a scale with 0.1g precision.
Calculating spoke specific weight from just one spoke at 7.2g would be inaccurate,
but weighing 10 spokes on a 0.1g scale gives quite precise results.
These spokes measured 269mm actual length, so
in terms of spoke specific weight: "one 269mm spoke weighs 72.0g"
and the weight per millimeter is 0.026765···g.
The 100% spoke specific weight is defined as
"2.0mm plain spoke, 1mm length weighs 0.025g", so
these spokes have a specific weight of 104.143...%.
So roughly 104% is fair.
They were lighter than I expected.
This is probably because the PowerTap hub flanges don't have
slots cut for flat spokes,
preventing the aero spokes from being made too flat.
Done.
Just a side note: since I didn't completely disassemble the wheel,
it doesn't meet the criteria I arbitrarily set for "wheel rebuild today" (and so on).
↑ The spoke heads don't protrude at all beyond the hub flange, so
there shouldn't be any interference problems.
Similar work I've done includes
converting a Bontrager PowerTap hub wheel to reverse spoking (→here), and
solving an interference problem with Campagnolo 11-speed that didn't exist
when the original R-SYS came out (→here).
With the R-SYS issue, I didn't write about it at the time, but
the flange had thick sidewalls, so
I ground it down to a point where it wouldn't interfere with the sprocket.