Campag Disc Brakes - video
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dereksmalls
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Good scoop. Radial spoking on the rear disc side. Hmmm... Must figure most of the braking forces are at the front, which they are, but I still didn't think the non drive side with discs would be laced radially. Do they do that anywhere in the mountain bike world?
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jimborello
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They also have what it seems g3 lacing in the front wheel, it looks like the wheelset is backwards ja
Calnago wrote:Good scoop. Radial spoking on the rear disc side. Hmmm... Must figure most of the braking forces are at the front, which they are, but I still didn't think the non drive side with discs would be laced radially. Do they do that anywhere in the mountain bike world?
They figured out the torsional moment of the hub shell... It was about time.
I'll take your word for it, because I don't really know that means in layman's terms. I do know that despite the low spoke count on Campy's G3 wheels, they are rock solid even for a heavier guy like me, at least on a rim braked system.
I would love it if you could go into a bit more detail about the "figured out the torsional moment" thing you mention.
I would love it if you could go into a bit more detail about the "figured out the torsional moment" thing you mention.
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Ok then, so how did they overcome the problem of putting a disk on the side of radial laced spokes? They didn't do that on the front...
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Sorry, first for the sarcasm in the first post, then for sending the second without finishing the explanation. On the phone in the Alps, not easy.
As I said, the rim generates torque in one direction, the disc in the opposite.
It doesn't really matter that much in which side of the hub you want to put the spokes that counteract the tendency of the rim to spin in the opposite direction to the hub.
Both flanges of the hub are joined by a hollow cylinder. It is the shape with the best torsional moment of inertia, this is the shape that can best resist the tendency of the spokes on one side to make the flange rotate in one direction while the disc attachment tries to spin in the opposite.
The bigger the diameter of the hub shell, the thinner you can go in wall thickness, so there is a balance in which you get a very light and torsional stiff structure which has no problem to transfer the torque the disc can generate to the spokes in the other side. The deflection here is only some seconds. Negligible and unnoticeable while riding as the spokes deflect much more, not to mention the tire.
Just to show the whole picture, you have to keep the design within a certain slenderness ratio, this is a certain relation between thickness and diameter. Otherwise the cylinder will suffer from buckling. This even when, when not considering buckling, the moment of torsional inertia would allow for an even thinner wall and a bigger diameter. Buckling can be kept at bay by designing a cross section with stiffer parts, as a polygon. If you roll a paper sheet into a polygon, The corners of the polygon are in reality thicker in the direction of the torque for certain orientations of the polygon, and that retards buckling.
This slenderness ratio varies with the strength of the material, but it is a reverse exponential so very soon it's all about the geometry.
There is a Italian guy I know that can roughly tell the moment of inertia of a crane boom just by looking and knocking at it. He is 74 and has been working as a designer for the lifting industry in Italy, Germany and Austria for 50 years. He just pulled out his sleeve a lorry loader with 65m maximum height.
If the material is high strength It's all about the geometry at the end of the day
As I said, the rim generates torque in one direction, the disc in the opposite.
It doesn't really matter that much in which side of the hub you want to put the spokes that counteract the tendency of the rim to spin in the opposite direction to the hub.
Both flanges of the hub are joined by a hollow cylinder. It is the shape with the best torsional moment of inertia, this is the shape that can best resist the tendency of the spokes on one side to make the flange rotate in one direction while the disc attachment tries to spin in the opposite.
The bigger the diameter of the hub shell, the thinner you can go in wall thickness, so there is a balance in which you get a very light and torsional stiff structure which has no problem to transfer the torque the disc can generate to the spokes in the other side. The deflection here is only some seconds. Negligible and unnoticeable while riding as the spokes deflect much more, not to mention the tire.
Just to show the whole picture, you have to keep the design within a certain slenderness ratio, this is a certain relation between thickness and diameter. Otherwise the cylinder will suffer from buckling. This even when, when not considering buckling, the moment of torsional inertia would allow for an even thinner wall and a bigger diameter. Buckling can be kept at bay by designing a cross section with stiffer parts, as a polygon. If you roll a paper sheet into a polygon, The corners of the polygon are in reality thicker in the direction of the torque for certain orientations of the polygon, and that retards buckling.
This slenderness ratio varies with the strength of the material, but it is a reverse exponential so very soon it's all about the geometry.
There is a Italian guy I know that can roughly tell the moment of inertia of a crane boom just by looking and knocking at it. He is 74 and has been working as a designer for the lifting industry in Italy, Germany and Austria for 50 years. He just pulled out his sleeve a lorry loader with 65m maximum height.
If the material is high strength It's all about the geometry at the end of the day
It's not a mistake but a convention. You could do it inversely and it would still work.
I like the idea of doing it "ideally right" and placing the tangential spokes close to the torque source, though.
But I also like Campag's design here:
-the NDS radial spokes add lateral stiffness to the wheel. Had they go for cross lacing there, there would be a tiny bit more of lateral deflection overall.
- they have the cross lacing where we are used to see it.
-some may argue they cared more about power than braking transfer. It is splitting hairs in reality but sounds radical
I like the idea of doing it "ideally right" and placing the tangential spokes close to the torque source, though.
But I also like Campag's design here:
-the NDS radial spokes add lateral stiffness to the wheel. Had they go for cross lacing there, there would be a tiny bit more of lateral deflection overall.
- they have the cross lacing where we are used to see it.
-some may argue they cared more about power than braking transfer. It is splitting hairs in reality but sounds radical
a local dealer told me a strange story yesterday, I don't know if it is the truth and it does sound crazy, but he told me a Shimano rep told him the story.
I generally trust the guy and he's not a shit talker:
Apparently the disc brakes are manufactured by Shimano.
This was rather shocking to hear, but the story goes that Campagnolo almost went bankrupt 5-6 years ago and Shimano took this chance and now owns 51% of Campas shares.
The story is almost unbelievable but I'm sure someone with some accountancy background can perhaps look this up and verify this info?
Don't shoot me, I'm just telling what I heard and wanted to check if more people know if this story is legit?
I generally trust the guy and he's not a shit talker:
Apparently the disc brakes are manufactured by Shimano.
This was rather shocking to hear, but the story goes that Campagnolo almost went bankrupt 5-6 years ago and Shimano took this chance and now owns 51% of Campas shares.
The story is almost unbelievable but I'm sure someone with some accountancy background can perhaps look this up and verify this info?
Don't shoot me, I'm just telling what I heard and wanted to check if more people know if this story is legit?
But I could be wrong
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