Nomu Lab Diary

Bora Ultra 35

I received both front and rear wheels
of a Bora Ultra 35 from a customer.
Speaking in terms of model year, it's only been produced for one year—
a narrow rim tubular,
what I'd call a phantom wheelset.

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Starting with the front wheel.
Both wheels need inspection, and since we're transitioning to tape,
the customer wants the rim cement bed removed.

On top of that, the front wheel has a bent spoke
where the tape is attached,
so the customer wants it replaced.
They asked me to replace any other spokes I judge to need replacement,
but it turned out only this one spoke required replacement.

RIMG1421amx17.jpg
↑this one

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You can see the deformation even with spoke tension applied.

This customer isn't the original owner of this wheel.
I wonder if there was no shop capable of fixing this
in the vicinity of the previous owner.
Oh, and I forgot to mention earlier,
but the customer also wants the rear wheel's Shimano freebody
swapped out for a Campagnolo one.

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After spoke replacement,
this is a provisional center from when I did a quick lateral truing.
The lateral runout could still be tightened,
but even if I do that, the overall trend
of the rim being shifted to the right
won't change.

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I tightened the runout and got the center sorted.

RIMG1452amx17.jpg
↑the replaced spoke
There's lateral deformation,
so what's visible right now is
the narrow side of the spoke's flat section.

RIMG1453amx17.jpg
↑this is where the bend starts,
and since the lateral deformation can be straightened by hand,

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I made it as flat as possible.
The image above is not the same angle as before;
what's visible now is
the wide side of the spoke's flat section.

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When I place a straightedge parallel across the spoke head,

RIMG1457amx17.jpg
↑you can see deformation in the fore-aft direction like this.
Initially I thought it was just lateral force damage,
but something got caught in the rotating wheel.
Since one spoke took all the load,
it seems like something like a shopping bag
hung from the handlebars at low speed got tangled up.

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Now for the rear wheel.
The left side of the image has been dark lately
because cardboard boxes containing wheels
are stacked up over there.

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It has a steel freebody for Shimano,
but this will be swapped for
the Campagnolo freebody sent by the customer.
It's unlikely this will change the wheel center much
(just from the right endnut tightening),
but I'm replacing it first just to be safe.

RIMG1431amx17.jpg
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The rim was shifted to the right—
just barely enough to chalk it up to age.
A little shifted right from the start + shifted further right with time,
that sort of thing.
There was barely any lateral runout.
There's no sign of clumsy tinkering,
so it seems like it was just taken out of the box and ridden as-is
(if there'd been any decent maintenance history,
the front wheel wouldn't have been that far out of center).

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I centered it.

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before

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after
I removed the rim cement bed.
This is what took the most work time.

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The valve bushes WH-BUU002
were first generation (top image, left),
so I switched them to the current third generation.
I returned the two first-gen ones to the customer.

Why did I replace them?
Because most tubular tire valve extenders
are the type without cut threads,
and the dimensions tend to be slightly oversized
relative to the valve diameter itself,
and with the first-gen valve bushes
they often don't fit smoothly.

RIMG1446amx17.jpg
Continental Competition tape
was applied to the rim
(no adhesive needed with tape),
as requested.

The tire's max pressure is 12 bar, so
if the floor pump's limit allows,
I inflated it to 12 bar
and let it sit until just before mounting
so it would stretch a bit and be easier to seat.

RIMG1448amx17.jpg
No valve extender was included,
so I used one from the shop.
The valve core barely doesn't protrude from the rim
given the valve length and rim height relationship,
so ideally something as short as possible,

RIMG1459amx17.jpg
and I used the 26mm one
from Kobo Akamatz (←shameless plug)
valve extender options of
26, 44, 58, and 82mm.

RIMG1461amx17.jpg
It has a tapered section from the end of the threads,
and tightens down without any tape
to create a proper seal.

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The 26mm refers to the overall length,

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and the actual extension is
somewhere around 15–16mm.