Why have Campag gone back to using a metal bush instead of ceramic bearing on the lower 12 speed jockey wheel?
First iterations of 11 speed had ceramic bushes in both wheels then came a ceramic bearing in the lower jockey wheel now they have metal bushes in both, as on the cheaper groupsets. They have also used red hub covers – introduced with the 11 speed ceramic bearing lower jockey wheel – which fooled me to thinking they were ceramic bearings until I took them apart. Is there a reason other than economy?
Campagnolo SR, 12 speed jockey wheels?
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Lots of testing, lot of real world experience, final result was that ceramic bushings (as in SR12, RD-SR612) offer a very small performance advantage, not significantly less than the ceramic ball-bearing assemblies originally used in SR11. Record 12 uses sintered bushings (RE-RE612)wilwil wrote: ↑Mon Feb 18, 2019 10:41 amWhy have Campag gone back to using a metal bush instead of ceramic bearing on the lower 12 speed jockey wheel?
First iterations of 11 speed had ceramic bushes in both wheels then came a ceramic bearing in the lower jockey wheel now they have metal bushes in both, as on the cheaper groupsets. They have also used red hub covers – introduced with the 11 speed ceramic bearing lower jockey wheel – which fooled me to thinking they were ceramic bearings until I took them apart. Is there a reason other than economy?
The gain over sintered bushings is small ... so it's more a cost / advantage sum than just a question of cost.
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Head Tech, Campagnolo main UK ASC
Pls contact via velotechcycling"at"aim"dot"com, not PM, for a quicker answer. Thanks!
Head Tech, Campagnolo main UK ASC
Pls contact via velotechcycling"at"aim"dot"com, not PM, for a quicker answer. Thanks!
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I don't think a lot of real world testing was really needed to know that the very small performance advantage was indeed, very small... but in the whacky world of bicycle marketing.... "spin" is everything... 15 seconds no less... that's 15 seconds of "must have marketing hype", I feel sooo sloooww without it... lol...
Super Record 11 Ceramic lower pulley...
Super Record 11 Ceramic lower pulley...
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In short, it means made by compressing the (hot) constituent powders. It can have lots of cost or structural advantages. For example making super hard steels which are difficult to get by traditional methods. For bushings, I just googled a bit and noticed a claim of dry self-lubrification while on another page I've read about a certain porosity which holds the lubricant nicely in.