I once rode an Orbea Aqua, a budget aluminum frame bike.
The reason I chose it was that among the dozens of complete bikes at my previous workplace, I searched for ones with unusually short head tube length relative to frame size, and then systematically checked each frame for alignment issues using a specific method.
Only two frames passed inspection: an Orbea Aqua and a Kona (Coratec RT Coronnes), and I chose the Aqua.
This doesn't mean Coratec or Orbea makes frames with particularly high precision.
Mass producers probably can't intentionally achieve this; the ones that passed my inspection with my jigs simply happened to be coincidentally made with precision good enough to hide any frame misalignment.
Just like there's inconsistency in how complete wheels are assembled, frame precision naturally has some variation.
Once you start worrying about this stuff, you end up going to custom frames from trusted builders—and that's actually what happened to me.
That said, I'll probably still buy off-the-shelf frames from manufacturers without worrying about alignment.
Anyway, that Orbea Aqua—back then it was the cheapest model but was made in Spain
(mine was Spanish-made too).
At some point, the frame skeleton changed slightly and it became made in China.
The biggest difference between this Chinese-made Aqua and the Spanish version is that the ZeroStack headset cup pressed into the head tube is steel, with bearing balls housed in a retainer bearing on the cup itself.
Since it's not an angular contact cartridge bearing, if the headset gets damaged, repairs are a real hassle.
So that's the setup, and—
this is a Merida Scultura complete bike, but its headset is damaged and the steering has resistance and sticking in the center—
that "gets stuck in the middle" symptom.
When this happens, no-hands riding becomes impossible (though it varies), and if it gets really bad, you can feel it in the steering feedback.
So I tried to replace the cartridge bearing, but turns out this one also uses the retainer bearing system on the cup.
To find the cup dimensions, I had to pull it from the frame temporarily, then reinstall it 90° offset from its original orientation—a traditional makeshift repair—with plans to swap it later for a cartridge bearing-type ZeroStack headset.
But there was another complication.
Standard ZeroStack cups for 1 1/8" upper and 1 1/2" lower have press-fit outer diameters (and frame inner diameters) of
44mm upper and 56mm lower.
But this frame had 44mm upper and 55mm lower.
The customer didn't contact the frame distributor, but using the exact same headset for repairs would likely be more expensive long-term.
After searching around, I found Ritchey makes a 55mm lower cup, but they only sell the lower piece separately.
I couldn't find the 44mm upper sold separately, so I was thinking I'd be forced to buy complete sets like 44/56mm or 44/44mm and end up with leftovers—
but then I found that Syncros, Scott's parts brandthat's become a zombie brand, made a 44/55mm complete ZeroStack headset at a better price.
Apparently Scott uses this size on some complete bike models.
So I pulled the fork.
This is the second time in about a week that I've removed the headset cup, and the first time removing the lower headset race from the fork.
On an unrelated note, Campagnolo's integral headset specs for the frame side—the head tube dimensions—are the same whether the fork steerer is 1" or 1 1/8".
This means that on the same frame, if you change the corresponding headset, you can install either a 1" fork or a 1 1/8" (back then called oversize) fork.
And since the same head tube size accommodates two different fork steerer diameters, as the steerer gets fatter, the bearing balls must get smaller to avoid interference.
In the diagram above, oversize bearings use 1/8" (or 4/32") balls, but the bearings for 1" steerer forks use 5/32" balls.
The metric dimensions are in the diagram, but very roughly speaking,
they're about "just over 3mm" and "just under 4mm" respectively—
that's a pretty big difference, so oddly enough, the 1" headset was more durable.
Of course, front end stiffness is far more dependent on fork steerer diameter, so a 1" fork with a stronger headset isn't necessarily (in terms of stiffness) stronger.
The original bearing's retainer on the lower 1 1/2" cup had smaller balls.
The pitting damage was worse on the lower cup too.
Since the situation is different from Campagnolo's headset, if I adjust the cup dimensions right, I feel like I could fit the lower bearing with the same size balls as the upper—but I won't.
↑Lower cup pitting.
This was causing the "gets stuck in the middle" problem.
↑The upper cup, being steel, had rust spots breaking out from sweat damage.
↑Original steel cup
↑Aluminum cup for cartridge bearing
If you count the pressed-in cup as part of the frame, a 50g difference is pretty substantial.
Done. Speaking of Syncros, the first thing that comes to mind is their hinge-style stem with the handlebar clamp side hinging and the steerer clamp side fixed with a bolt for ahead-type stems, but the current Syncros lineup has none of those (if you're interested, search "syncros hinged stem").
Aside from one road model with a quick-release top cap, they only make conventional 4-bolt stems.
Back when MTB stems were 1" quill-style, they were a real manufacturer (not just a brand!) making all sorts of components—
but geez, just checked and they don't even make seatposts anymore, not those offset-free, front-and-rear lever type seatposts that used to be called "the Syncros seatpost."
Are they serious? If you're interested, search "syncros retro seatpost" and so on.
↑This is mine, a vintage Syncros titanium bottom bracket.
Like "Intel Inside," there was a "Syncros Inside" sticker included, and it's nostalgic to think there was an era when having Syncros parts on your bike was something to be proud of.
The reason I chose it was that among the dozens of complete bikes at my previous workplace, I searched for ones with unusually short head tube length relative to frame size, and then systematically checked each frame for alignment issues using a specific method.
Only two frames passed inspection: an Orbea Aqua and a Kona (Coratec RT Coronnes), and I chose the Aqua.
This doesn't mean Coratec or Orbea makes frames with particularly high precision.
Mass producers probably can't intentionally achieve this; the ones that passed my inspection with my jigs simply happened to be coincidentally made with precision good enough to hide any frame misalignment.
Just like there's inconsistency in how complete wheels are assembled, frame precision naturally has some variation.
Once you start worrying about this stuff, you end up going to custom frames from trusted builders—and that's actually what happened to me.
That said, I'll probably still buy off-the-shelf frames from manufacturers without worrying about alignment.
Anyway, that Orbea Aqua—back then it was the cheapest model but was made in Spain
(mine was Spanish-made too).
At some point, the frame skeleton changed slightly and it became made in China.
The biggest difference between this Chinese-made Aqua and the Spanish version is that the ZeroStack headset cup pressed into the head tube is steel, with bearing balls housed in a retainer bearing on the cup itself.
Since it's not an angular contact cartridge bearing, if the headset gets damaged, repairs are a real hassle.
So that's the setup, and—
this is a Merida Scultura complete bike, but its headset is damaged and the steering has resistance and sticking in the center—
that "gets stuck in the middle" symptom.
When this happens, no-hands riding becomes impossible (though it varies), and if it gets really bad, you can feel it in the steering feedback.
So I tried to replace the cartridge bearing, but turns out this one also uses the retainer bearing system on the cup.
To find the cup dimensions, I had to pull it from the frame temporarily, then reinstall it 90° offset from its original orientation—a traditional makeshift repair—with plans to swap it later for a cartridge bearing-type ZeroStack headset.
But there was another complication.
Standard ZeroStack cups for 1 1/8" upper and 1 1/2" lower have press-fit outer diameters (and frame inner diameters) of
44mm upper and 56mm lower.
But this frame had 44mm upper and 55mm lower.
The customer didn't contact the frame distributor, but using the exact same headset for repairs would likely be more expensive long-term.
After searching around, I found Ritchey makes a 55mm lower cup, but they only sell the lower piece separately.
I couldn't find the 44mm upper sold separately, so I was thinking I'd be forced to buy complete sets like 44/56mm or 44/44mm and end up with leftovers—
but then I found that Syncros, Scott's parts brand
Apparently Scott uses this size on some complete bike models.
So I pulled the fork.
This is the second time in about a week that I've removed the headset cup, and the first time removing the lower headset race from the fork.
On an unrelated note, Campagnolo's integral headset specs for the frame side—the head tube dimensions—are the same whether the fork steerer is 1" or 1 1/8".
This means that on the same frame, if you change the corresponding headset, you can install either a 1" fork or a 1 1/8" (back then called oversize) fork.
And since the same head tube size accommodates two different fork steerer diameters, as the steerer gets fatter, the bearing balls must get smaller to avoid interference.
In the diagram above, oversize bearings use 1/8" (or 4/32") balls, but the bearings for 1" steerer forks use 5/32" balls.
The metric dimensions are in the diagram, but very roughly speaking,
they're about "just over 3mm" and "just under 4mm" respectively—
that's a pretty big difference, so oddly enough, the 1" headset was more durable.
Of course, front end stiffness is far more dependent on fork steerer diameter, so a 1" fork with a stronger headset isn't necessarily (in terms of stiffness) stronger.
The original bearing's retainer on the lower 1 1/2" cup had smaller balls.
The pitting damage was worse on the lower cup too.
Since the situation is different from Campagnolo's headset, if I adjust the cup dimensions right, I feel like I could fit the lower bearing with the same size balls as the upper—but I won't.
↑Lower cup pitting.
This was causing the "gets stuck in the middle" problem.
↑The upper cup, being steel, had rust spots breaking out from sweat damage.
↑Original steel cup
↑Aluminum cup for cartridge bearing
If you count the pressed-in cup as part of the frame, a 50g difference is pretty substantial.
Done. Speaking of Syncros, the first thing that comes to mind is their hinge-style stem with the handlebar clamp side hinging and the steerer clamp side fixed with a bolt for ahead-type stems, but the current Syncros lineup has none of those (if you're interested, search "syncros hinged stem").
Aside from one road model with a quick-release top cap, they only make conventional 4-bolt stems.
Back when MTB stems were 1" quill-style, they were a real manufacturer (not just a brand!) making all sorts of components—
but geez, just checked and they don't even make seatposts anymore, not those offset-free, front-and-rear lever type seatposts that used to be called "the Syncros seatpost."
Are they serious? If you're interested, search "syncros retro seatpost" and so on.
↑This is mine, a vintage Syncros titanium bottom bracket.
Like "Intel Inside," there was a "Syncros Inside" sticker included, and it's nostalgic to think there was an era when having Syncros parts on your bike was something to be proud of.