Another day, another wheel (and so on).
A customer left a Corima Medium rear wheel with me.
After years of use it's gotten loose, plus strange noises are coming from the hub,
so they want it rebuilt.
Sure enough, it's abnormally loose. Looser than any new off-the-shelf wheel should be.
I thought maybe the rim had shifted toward the freewheel side,
but the centering is actually good and the runout is minimal (barely noticeable while riding).
Whoa, this is it!
The sticker is from the first-generation Medium. And this is probably the real original.
The current Corima lineup is 32/47/73mm depth with wider carbon rims,
but originally the Corima rim only came in one model—the 40mm "Aero"
(we're talking rim alone here; they had other models like the Batton wheel),
and this came in different spoke hole counts for numerous OEM customers:
like the rim for Campagnolo's first-generation Bora,
Ambrosio's X-Carbo (though the later version was ZIPP's MID-V285),
and Zyppé's C416 (carbon, 40mm deep, 16 holes)
—it was a super long-seller.
Added to that were the 24mm low-profile "Winium" and
the "Medium," which had the same depth as the Aero but was lighter.
The Medium's positioning was supposed to be "Aero but lighter,"
and the first-generation Medium actually had a lighter rim itself than the Aero.
But later Mediums (as complete wheels)
only used thinner spokes than the Aero wheels,
so they were slightly lighter—essentially a lazy shortcut
where they shared the same rim as the Aero.
This Medium, despite not being tensioned that hard,
has the rim sidewall (the flat area inboard of the brake track)
rippled and flex when you push it with your finger.
This is unique to the first-generation Medium.
Back then, maybe threatened by the lightness of ZIPP's MID-V280 and V285,
conservative Corima made the unusual choice to chase lightness.
Among all the Mediums, only the first generation has a measured weight
comparable to the Winium.
(measured as a complete assembled wheel, not just the rim)
I'll get into that later. First, let's rebuild.
The valve holes on rims from that era were positioned opposite to most rims—
what this blog calls "reverse rims."
↑The hub flanges have extra holes so it's hard to see, but
in this image we have the so-called "left drop."
With the requirement that the four spokes—the last crossing spoke and its opposite partner—
don't straddle the valve hole,
a left drop becomes Italian lacing (or reverse Italian lacing).
When passing a drive-side spoke through the top flange,
whether you drop a non-drive spoke to the left or right neighbor of the bottom flange
depends on the asymmetric lacing pattern. If the drive side is X-pattern and non-drive is Y-pattern,
and both X/2 and Y/2 are even or both odd,
the left/right drop relationship doesn't flip.
But with 46-spoke lacing, X is 2 (even) and Y is 3 (odd),
so the relationship flips and a right drop gives Italian lacing.
However, that's for standard rims with normal hole positioning—
for a reverse rim like this one with 46-spoke Italian lacing,
it's the opposite of right drop, giving us left drop.
Laced it up.
Black hub, 24 holes, black semi-comp 46-spoke Italian laced, with wire connectors.
Tensioned it as tight as we could—your wish is my command, hehehehe.
Going back to the first-generation Medium as a complete wheel,
when it was current, the catalog weight for
a 700C tubular 24-hole rear wheel was
Aero: 840g, Medium: 760g, Winium: 750g.
(The weight difference between Shimano and Campagnolo freebodies
supposedly doesn't exist, though it probably does)
At face value, the rim weight difference between Winium and Medium looks like just 10g,
but they used different spokes so simple comparison doesn't work.
Contemporary catalog and my notes.
The Aero, Medium, and Winium all used the same hub model.
Carbon hubs and piercing hubs (see here) hadn't come out yet.
That's what we can learn from this catalog.
It lists the complete wheel weights and the Aero and Winium rim weights.
Actually, Medium rim wasn't sold as a separate component.
For later Mediums, it was just
"buy an Aero rim and stick a Medium sticker on it,"
so no single rim sales there either.
The key point here is that Aero and Winium used CX spokes,
while Medium used CX-RAY spokes.
For some reason the non-drive spoke length differs by 1mm between Aero and Medium,
but if I calculate approximate spoke weight from specific gravity:
You get this. I added the estimates in blue pen.
If we assume the hub and nipples (everything but rim and spokes) weigh 270g,
then the Medium rim would be 379g.
From my experience, the original Medium was lighter than the Winium,
so the rim should be lighter still...
What? Just weigh the rim and measure it directly? Stop being so cagey?
Shut up, quit telling me what to do
↑ wow what a terrible attitude
Sorry for the wait!
I got shot up by the thought police and became a piercing body but
These images came out fine!
I added the measured values in red pen!
↑Stop iiiiiit!
A customer left a Corima Medium rear wheel with me.
After years of use it's gotten loose, plus strange noises are coming from the hub,
so they want it rebuilt.
Sure enough, it's abnormally loose. Looser than any new off-the-shelf wheel should be.
I thought maybe the rim had shifted toward the freewheel side,
but the centering is actually good and the runout is minimal (barely noticeable while riding).
Whoa, this is it!
The sticker is from the first-generation Medium. And this is probably the real original.
The current Corima lineup is 32/47/73mm depth with wider carbon rims,
but originally the Corima rim only came in one model—the 40mm "Aero"
(we're talking rim alone here; they had other models like the Batton wheel),
and this came in different spoke hole counts for numerous OEM customers:
like the rim for Campagnolo's first-generation Bora,
Ambrosio's X-Carbo (though the later version was ZIPP's MID-V285),
and Zyppé's C416 (carbon, 40mm deep, 16 holes)
—it was a super long-seller.
Added to that were the 24mm low-profile "Winium" and
the "Medium," which had the same depth as the Aero but was lighter.
The Medium's positioning was supposed to be "Aero but lighter,"
and the first-generation Medium actually had a lighter rim itself than the Aero.
But later Mediums (as complete wheels)
only used thinner spokes than the Aero wheels,
so they were slightly lighter—essentially a lazy shortcut
where they shared the same rim as the Aero.
This Medium, despite not being tensioned that hard,
has the rim sidewall (the flat area inboard of the brake track)
rippled and flex when you push it with your finger.
This is unique to the first-generation Medium.
Back then, maybe threatened by the lightness of ZIPP's MID-V280 and V285,
conservative Corima made the unusual choice to chase lightness.
Among all the Mediums, only the first generation has a measured weight
comparable to the Winium.
(measured as a complete assembled wheel, not just the rim)
I'll get into that later. First, let's rebuild.
The valve holes on rims from that era were positioned opposite to most rims—
what this blog calls "reverse rims."
↑The hub flanges have extra holes so it's hard to see, but
in this image we have the so-called "left drop."
With the requirement that the four spokes—the last crossing spoke and its opposite partner—
don't straddle the valve hole,
a left drop becomes Italian lacing (or reverse Italian lacing).
When passing a drive-side spoke through the top flange,
whether you drop a non-drive spoke to the left or right neighbor of the bottom flange
depends on the asymmetric lacing pattern. If the drive side is X-pattern and non-drive is Y-pattern,
and both X/2 and Y/2 are even or both odd,
the left/right drop relationship doesn't flip.
But with 46-spoke lacing, X is 2 (even) and Y is 3 (odd),
so the relationship flips and a right drop gives Italian lacing.
However, that's for standard rims with normal hole positioning—
for a reverse rim like this one with 46-spoke Italian lacing,
it's the opposite of right drop, giving us left drop.
Laced it up.
Black hub, 24 holes, black semi-comp 46-spoke Italian laced, with wire connectors.
Tensioned it as tight as we could—your wish is my command, hehehehe.
Going back to the first-generation Medium as a complete wheel,
when it was current, the catalog weight for
a 700C tubular 24-hole rear wheel was
Aero: 840g, Medium: 760g, Winium: 750g.
(The weight difference between Shimano and Campagnolo freebodies
supposedly doesn't exist, though it probably does)
At face value, the rim weight difference between Winium and Medium looks like just 10g,
but they used different spokes so simple comparison doesn't work.
Contemporary catalog and my notes.
The Aero, Medium, and Winium all used the same hub model.
Carbon hubs and piercing hubs (see here) hadn't come out yet.
That's what we can learn from this catalog.
It lists the complete wheel weights and the Aero and Winium rim weights.
Actually, Medium rim wasn't sold as a separate component.
For later Mediums, it was just
"buy an Aero rim and stick a Medium sticker on it,"
so no single rim sales there either.
The key point here is that Aero and Winium used CX spokes,
while Medium used CX-RAY spokes.
For some reason the non-drive spoke length differs by 1mm between Aero and Medium,
but if I calculate approximate spoke weight from specific gravity:
You get this. I added the estimates in blue pen.
If we assume the hub and nipples (everything but rim and spokes) weigh 270g,
then the Medium rim would be 379g.
From my experience, the original Medium was lighter than the Winium,
so the rim should be lighter still...
What? Just weigh the rim and measure it directly? Stop being so cagey?
Shut up, quit telling me what to do
↑ wow what a terrible attitude
Sorry for the wait!
I got shot up by the thought police and became a piercing body but
These images came out fine!
I added the measured values in red pen!
↑Stop iiiiiit!