Another day of wheels (and so on).
A customer entrusted me with a
Dura-Ace C50 tubular front wheel.
They wanted it rebuilt.
By the way, this is a different customer from yesterday's C36 tubular.
Dura-Ace hub, 24H
Mac spokes with a spoke specific gravity of about 62%—the kind that rust easily
Two-cross lacing both sides with the final cross unwoven on both sides.
Since this is a tubular rim spec,
there's no Ultegra grade equivalent,
but with tubeless, the rim is the same except cosmetically
(presumably—at least the weight is the same)
and the weight difference of the C50 front wheel
calculated from the stated weight is 24g,
which becomes 85g for the rear wheel.
The front wheel weight difference is mostly from spoke weight despite the different flange shape on the front hub,
and the rear wheel's larger weight difference is primarily due to the different material of the rear hub shaft—
the rear hub shaft accounts for about +60g,
and the spokes for about +25g.
People who buy wheels looking only at the combined front and rear weight
make shallow judgments like
"Dura-Ace is over 100g lighter!"
but in my opinion, with current models,
the Ultegra wheels might actually perform better than the Dura-Ace wheels.
The spoke specific gravity is 65% for CX-RAY/Aero Lite
and 78% for CX Sprint/Aero Comp, compared to
Dura-Ace's 62% and Ultegra's 71%—
they've subtly missed the mark,
so repairs can't be done with generic spokes,
and since Dura-Ace has lowered the spoke specific gravity too much,
with equal-diameter lacing, the Ultegra wheels would likely feel
stiffer and faster-rolling.
Dura-Ace's hub rotation is smoother, so
it might feel faster to ride... sure, there's that,
but it's not a factor that
surpasses the difference in spoke specific gravity.
Low-tension side (right side) feels mushy
High-tension side (left side) feels mushy
This feels way too soft.
It's hard to imagine it getting this slack from just years of regular use,
so maybe they got a dud unit to begin with...?
Even the off-the-shelf Ultegra C36 tubeless front wheel I worked on today
felt a bit firmer than this.
Though the spoke specific gravity difference might play a role here too.
It was running on tape instead of rim cement,
and the rim's outer edge is extremely clean.
The hub has some dirt showing actual use,
so it's definitely been ridden quite a bit.
This customer does own
clincher/tubeless wheels,
but being a tubular devotee, they use this wheel
as their go-to rather than just for special occasions.
When I tried to check the provisional center,
the hub shaft had play side-to-side,
and there were marks on the cone wrench flats too.
Since this hub won't be used in the rebuild,
I left the bearing adjustment as-is without touching it.
Rebuilt.
Chris King R45D hub, 24H
Black half CX Sprint, 64-spoke reverse Italian lacing.
I'll do the lacing later.
With Chris King's disc front hubs,
when the hub shell marking is straight up
and you look at it from the saddle position,
the lettering is printed at 180° phase, both backwards I think,
but this hub has the "Made in USA" one backwards
and the serial number one forwards.
I built it with the valve hole view of the hub shell phase set to
"Made in USA" (the backwards marking).
The hub felt stiff when spinning solo,
so I loosened the bearing adjustment, and then
lateral play appeared while I was building the wheel.
Maybe that was the intended initial setup.
Low-tension side, right side, CX-RAY side
This side will have the lacing done later,
so the final cross flutter will be nearly zero.
High-tension side, left side, CX Sprint side
To be fair, the rebuilt wheel actually feels
even firmer to squeeze than before.
And that's not because "more spoke tension is always better"—
I've stopped at a reasonable sweet spot.
Setting aside the hub change for this rebuild,
looking just at the spoke aspect,
changing to Ultegra spokes would result in
roughly the same weight increase.
But that's not equal-diameter lacing, since
the original Dura-Ace was 62/62%, Ultegra would be 71/71%, and
the half CX Sprint is 78/65%—
the lowest spec here is the one that'll roll fastest.
If you want a wheel that's just slightly lighter in hand but
might be a tension dud,
buying an off-the-shelf Dura-Ace is recommended.
A customer entrusted me with a
Dura-Ace C50 tubular front wheel.
They wanted it rebuilt.
By the way, this is a different customer from yesterday's C36 tubular.
Dura-Ace hub, 24H
Mac spokes with a spoke specific gravity of about 62%—the kind that rust easily
Two-cross lacing both sides with the final cross unwoven on both sides.
Since this is a tubular rim spec,
there's no Ultegra grade equivalent,
but with tubeless, the rim is the same except cosmetically
(presumably—at least the weight is the same)
and the weight difference of the C50 front wheel
calculated from the stated weight is 24g,
which becomes 85g for the rear wheel.
The front wheel weight difference is mostly from spoke weight despite the different flange shape on the front hub,
and the rear wheel's larger weight difference is primarily due to the different material of the rear hub shaft—
the rear hub shaft accounts for about +60g,
and the spokes for about +25g.
People who buy wheels looking only at the combined front and rear weight
make shallow judgments like
"Dura-Ace is over 100g lighter!"
but in my opinion, with current models,
the Ultegra wheels might actually perform better than the Dura-Ace wheels.
The spoke specific gravity is 65% for CX-RAY/Aero Lite
and 78% for CX Sprint/Aero Comp, compared to
Dura-Ace's 62% and Ultegra's 71%—
they've subtly missed the mark,
so repairs can't be done with generic spokes,
and since Dura-Ace has lowered the spoke specific gravity too much,
with equal-diameter lacing, the Ultegra wheels would likely feel
stiffer and faster-rolling.
Dura-Ace's hub rotation is smoother, so
it might feel faster to ride... sure, there's that,
but it's not a factor that
surpasses the difference in spoke specific gravity.
Low-tension side (right side) feels mushy
High-tension side (left side) feels mushy
This feels way too soft.
It's hard to imagine it getting this slack from just years of regular use,
so maybe they got a dud unit to begin with...?
Even the off-the-shelf Ultegra C36 tubeless front wheel I worked on today
felt a bit firmer than this.
Though the spoke specific gravity difference might play a role here too.
It was running on tape instead of rim cement,
and the rim's outer edge is extremely clean.
The hub has some dirt showing actual use,
so it's definitely been ridden quite a bit.
This customer does own
clincher/tubeless wheels,
but being a tubular devotee, they use this wheel
as their go-to rather than just for special occasions.
When I tried to check the provisional center,
the hub shaft had play side-to-side,
and there were marks on the cone wrench flats too.
Since this hub won't be used in the rebuild,
I left the bearing adjustment as-is without touching it.
Rebuilt.
Chris King R45D hub, 24H
Black half CX Sprint, 64-spoke reverse Italian lacing.
I'll do the lacing later.
With Chris King's disc front hubs,
when the hub shell marking is straight up
and you look at it from the saddle position,
the lettering is printed at 180° phase, both backwards I think,
but this hub has the "Made in USA" one backwards
and the serial number one forwards.
I built it with the valve hole view of the hub shell phase set to
"Made in USA" (the backwards marking).
The hub felt stiff when spinning solo,
so I loosened the bearing adjustment, and then
lateral play appeared while I was building the wheel.
Maybe that was the intended initial setup.
Low-tension side, right side, CX-RAY side
This side will have the lacing done later,
so the final cross flutter will be nearly zero.
High-tension side, left side, CX Sprint side
To be fair, the rebuilt wheel actually feels
even firmer to squeeze than before.
And that's not because "more spoke tension is always better"—
I've stopped at a reasonable sweet spot.
Setting aside the hub change for this rebuild,
looking just at the spoke aspect,
changing to Ultegra spokes would result in
roughly the same weight increase.
But that's not equal-diameter lacing, since
the original Dura-Ace was 62/62%, Ultegra would be 71/71%, and
the half CX Sprint is 78/65%—
the lowest spec here is the one that'll roll fastest.
If you want a wheel that's just slightly lighter in hand but
might be a tension dud,
buying an off-the-shelf Dura-Ace is recommended.