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Ceramic Bearings
Ceramic bearings are touted as being better than steel bearings. But we have to ask:
- Are ceramic bearings faster? When and how? What about side loads versus a 90° load on the bearing?
- Longevity— are ceramic bearings durable?
Drag
The claim of higher efficiency seems dubious, because this claim needs verification over time with real-world use— how a bearing performs when brand-new is irrelevant. Unless it’s needed for only one race and one has the budget to pay for that. But what does it do 1 month, 3 months, 6 months later with use?
To get the lowest drag, less rigorous sealing and a very light oil lubricant is required (not grease). Guess what happens when water and dirt intrude? Suddenly the bearings can become much worse than a well-sealed steel bearings.
Durability
What I hear from my local mechanic who has seen many a ceramic bearing come by is that the quality range is broad, and many fail very quickly.
One problem with some ceramic bearings is that they tear up the steel races. Another problem is that some are marginally sealed, and so the races corrode.
Here is my personal experience with ceramic bearings—
- ZIPP 303 and ZIPP 404 wheels: 4-5 years of use. Still smooth.
- Lightweight Obermayer rear wheel: 7000 miles of use, buttery smooth.
- Trek Madone 6.9 SSL bottom bracket: BB bearings bad after ~1500 miles.
- Trek Madone 6.9 SSL bottom bracket: BB and headset top and bottom bearings all bad after ~7000 miles (almost certainly was far sooner than that).
- ABEC 5 ceramic bearings for speed skates: clean them every few skates, or they’re toast.
And steel bearings:
- Lightweight Obermayer front wheel: 7000 miles of use, buttery smooth.
- Lightweight Ventoux 240 wheelset: ~3000 miles of use, buttery smooth.
- Lightweight VR8 front wheel: ~500 miles use by me on a demo wheel that likely has far more miles: buttery smooth.
- SRAM bottom bracket on my Moots mountain bike: bearings bad in ~300 miles. SRAM PressFit 30 bottom bracket bearings are not well sealed, so any water kills them quickly.
Bottom bracket
Want a solid bottom bracket? Shimano DuraAce with steel bearings. Is Shimano really so ignorant that they don’t produce a ceramic-bearing DuraAce? The quality of DuraAce over years of experience can hardly be criticized.
I just replaced my Trek Madone 6.9 SSL ceramic bottom bracket bearings (both bad on both bikes) with steel Shimano bearings. I see no point in paying for a ceramic BB bearing that is going to last me less than 3 months, if they last even that long.
