Another day working on wheels (and so on).
A customer brought in a rear wheel from a WH-7850-C24-TU.
The rim is carbon tubular.
They said it just doesn't feel right in terms of rolling,
so they wanted it rebuilt,
This rear wheel is built with different spoke counts on each side.
Neither side was laced with a final crossing originally,
but on the freewheel side I increased spoke weight and left off the final crossing,
while on the non-freewheel side I reused the spokes
but wove in the final crossing and tied them off.
The weight of the 10 freewheel-side spokes.
The nominal length was 304mm, but actual measurement showed closer to 303mm.
When I shined a light inside the rim before disassembly,
the freewheel-side spoke length looked long,
so I went with 302mm spokes for the rebuild.
The non-freewheel side looked like just the right length by my standards,
so I reused those as-is.
The spoke weight ratio for these spokes came to
66.8÷304÷10÷0.0257=85.500715９...so
85.5%.
From actual measurement at 303mm,
the calculation gives 0.85782894９...so
85.8%.
I was expecting something around 80%, a bit higher than CX Sprint's 78%,
but in reality it turned out somewhat larger—basically equivalent to a "flattened Campagnolo".
For the non-freewheel side spokes,
I calculated a rough figure beforehand
assuming they matched CX-RAY's 64.5% spoke weight ratio,
and when I put the spokes on the scale, they came out almost identical.
These wheel spokes aren't made by Sapim,
but I already knew that the non-freewheel side spoke
weight ratio was equivalent to CX-RAY.
So I've been doing non-freewheel side spoke replacements
with black CX-RAY straight-gauge spokes.
Rebuilt.
The freewheel side is black Campagnolo straight-gauge without final crossing,
and the non-freewheel side uses the original spokes
with the final crossing woven in and tied off.
There was a nipple with tool marks where the tool had been shallowly engaged on two diagonal corners of the square grip section,
and the resistance when turning was abnormally high—it felt like the spoke would twist.
So I loosened other sections until tension was completely released before removing it,
↑Looking closely, the inner edge face was crushed into a diamond shape.
So I replaced just that one nipple.
There's a rib-like protrusion on the outer edge of the grip section—
this is a Campagnolo Bullet red nipple.
Unlike the original Shimano nipple,
it doesn't have a Phillips cross on the outside that you can turn with a screwdriver,
but the grip section's flat-to-flat width is the same at 3.95mm (4mm)
and the length protruding from the rim is the same,
so I went with this.
By the way, since I completely disassembled the wheel this time,
I did weigh the rim,
and for a low-profile offset rim it was quite light.
In the successor 7900 series, the C24 only comes as asuspiciously-looking
carbon laminate WO or tubeless rim wheel,
so this rear wheel is quite a rare model.
The rim weight? No way I'm telling you that!
↑Man, that's a bad attitude
Sorry for the wait!
Please check out this image!
↑Stop it already!
A customer brought in a rear wheel from a WH-7850-C24-TU.
The rim is carbon tubular.
They said it just doesn't feel right in terms of rolling,
so they wanted it rebuilt,
This rear wheel is built with different spoke counts on each side.
Neither side was laced with a final crossing originally,
but on the freewheel side I increased spoke weight and left off the final crossing,
while on the non-freewheel side I reused the spokes
but wove in the final crossing and tied them off.
The weight of the 10 freewheel-side spokes.
The nominal length was 304mm, but actual measurement showed closer to 303mm.
When I shined a light inside the rim before disassembly,
the freewheel-side spoke length looked long,
so I went with 302mm spokes for the rebuild.
The non-freewheel side looked like just the right length by my standards,
so I reused those as-is.
The spoke weight ratio for these spokes came to
66.8÷304÷10÷0.0257=85.500715９...so
85.5%.
From actual measurement at 303mm,
the calculation gives 0.85782894９...so
85.8%.
I was expecting something around 80%, a bit higher than CX Sprint's 78%,
but in reality it turned out somewhat larger—basically equivalent to a "flattened Campagnolo".
For the non-freewheel side spokes,
I calculated a rough figure beforehand
assuming they matched CX-RAY's 64.5% spoke weight ratio,
and when I put the spokes on the scale, they came out almost identical.
These wheel spokes aren't made by Sapim,
but I already knew that the non-freewheel side spoke
weight ratio was equivalent to CX-RAY.
So I've been doing non-freewheel side spoke replacements
with black CX-RAY straight-gauge spokes.
Rebuilt.
The freewheel side is black Campagnolo straight-gauge without final crossing,
and the non-freewheel side uses the original spokes
with the final crossing woven in and tied off.
There was a nipple with tool marks where the tool had been shallowly engaged on two diagonal corners of the square grip section,
and the resistance when turning was abnormally high—it felt like the spoke would twist.
So I loosened other sections until tension was completely released before removing it,
↑Looking closely, the inner edge face was crushed into a diamond shape.
So I replaced just that one nipple.
There's a rib-like protrusion on the outer edge of the grip section—
this is a Campagnolo Bullet red nipple.
Unlike the original Shimano nipple,
it doesn't have a Phillips cross on the outside that you can turn with a screwdriver,
but the grip section's flat-to-flat width is the same at 3.95mm (4mm)
and the length protruding from the rim is the same,
so I went with this.
By the way, since I completely disassembled the wheel this time,
I did weigh the rim,
and for a low-profile offset rim it was quite light.
In the successor 7900 series, the C24 only comes as a
carbon laminate WO or tubeless rim wheel,
so this rear wheel is quite a rare model.
The rim weight? No way I'm telling you that!
↑Man, that's a bad attitude
Sorry for the wait!
Please check out this image!
↑Stop it already!