Ceramic Bottom Bracket

Discuss light weight issues concerning road bikes & parts.
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muntos
Posts: 208
Joined: Wed May 29, 2013 5:41 pm
Location: Romania

by muntos

Does a ceramic BB worth the investment ? I have a Scott Foil with BB86 PressFit (Shimano Ultegra BB I think, anyway the one shipped with the frame) and I noticed that the cranks doesn't spin as smooth as my friend's bike BB.
So, I have some questions:
1) Does a Ceramic BB that will make the cranks run smoother make a difference in terms of performance (Watts gained) ?
2) What buget ceramic BB for BB86 (under 150 Euro/USD) ? I've found from Rotor, FSA and Stronglight but I don't know anything about how good the bearings from these manufactures are.

pdlpsher1
Posts: 1484
Joined: Thu Jul 19, 2012 6:09 pm
Location: CO

by pdlpsher1

What reduces bearing friction are the seals and grease, not the materials of the balls. To reduce friction to a minimal level you can take an inexpensive steel sealed bearing and remove the seals and replace the grease with a low viscosity oil. Or as a compromise get a sealed bearing with a non-contact seal. The common ceramic bearings that you see on videos most likely have non-contact seals and low viscosity type grease for reduced friction. The ceramic balls themselves don’t reduce friction.


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AJS914
Posts: 1964
Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

It's not worth it. You will pay a lot of money to save a watt or two.

muntos
Posts: 208
Joined: Wed May 29, 2013 5:41 pm
Location: Romania

by muntos

Thanks for the info, in this case I will stick with something from Shimano.

nemeseri
Posts: 658
Joined: Tue Apr 07, 2015 5:40 pm

by nemeseri

muntos wrote:
Tue Mar 20, 2018 6:02 pm
I noticed that the cranks doesn't spin as smooth as my friend's bike BB.
Because yours still have some bearing grease in them.
There is some difference in BB bearing performance under load, but it's probably something you shouldn't worry about. If you feel that your BB is slowing you, I'm 98% sure it's only in your head.

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slake21
Posts: 121
Joined: Tue Oct 18, 2016 9:59 am
Location: EU

by slake21

I've bought C-Bear BB because my Shimano was creaking. Got it because it's aluminium and the ceramic bearing is just a plus.

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swright
Posts: 5
Joined: Fri Mar 02, 2018 4:29 pm

by swright

This article (https://university.trisports.com/2016/1 ... end-a-lot/) from TriSportsLounge (dated January 2018) includes the following summary of savings per component with ceramic bearings:

* Derailleur Pulleys: 0.5-2.0 watts
* Wheel Hubs: 0.5-1.0 watts
* Bottom Brackets: 0.03-0.5 watts

Looks like bang-for-the-buck is definitely not in BBs. I'm unclear whther the wheel hubs savings is per hub or for both hubs combined (I would guess that's per hub).

The author also quite sensibly note that the realized savings depend heavily on what you start with -- replacing your Shimano 105 BB with ceramic bearings will realize a bigger savings than swapping your Dura-Ace BB for CeramicSpeed.

I have seen pulleys from from Kogel, CeramicSpeed, C-Bear, Digirit and Tacx -- what are folks experiences and recommendations on upgrade ceramic-bearing pulley wheels?

Scott

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