Campagnolo SR, 12 speed jockey wheels?

Discuss light weight issues concerning road bikes & parts.
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wilwil
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Joined: Thu Sep 23, 2010 5:47 pm

by wilwil

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?

by Weenie


graeme_f_k
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by graeme_f_k

wilwil wrote:
Mon Feb 18, 2019 10:41 am
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?
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)

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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Calnago
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by Calnago

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...
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scb
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by scb

I waiting for Ceramic Speed OSPWs for the 12 speed--no timeline yet from CS but they told me to check back this summer. I have them on by C60 with EPS and am happy with them.

wilwil
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Joined: Thu Sep 23, 2010 5:47 pm

by wilwil

The bushings in my SR12 look like metal not white ceramic. What does sintered mean?

Alexandrumarian
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by Alexandrumarian

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.

by Weenie


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