Ebay ceramic bearings - balls, not sealed units

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by patchsurfer

I stumbled across these on ebay and wondered if they'd be a worthwhile replacement, as much for longevity's sake as anything else. Loose, ceramic bearings that I'd fit in the cages in my zonda hubs. Any thoughts / wisdom?

http://www.ebay.com/itm/5-32-034-Ball-B ... 1593689777



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by StradaJon

They may be too hard for the race and cause damage.
Strada Hand Built Wheels

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by patchsurfer

Thanks Jon,

Been having a read around...I had no idea bearings were such a huge subject...and so many strong opinions. From what I've read, grade 25 steel bearings are the way to go for my application...

Cheers, Simon

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by mattr

It's a multi billion dollar industry, many companies have entire departments that *only* deal with bearings and lubrication. The bike industry is a couple of decades behind even slightly tech aware industries....... and also a couple of orders of magnitude less clued up!

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by sungod


silicon nitride ceramic balls will be hard, but toughness is a different matter, it'll depend how the bulk material was produced and processed

end product could be produced with inferior methods and 'sifted' into different size tolerance bands (i.e. grades), then you have 'high grade' balls, even though they have poor mechanical properties

being sold cheap on ebay doesn't necessarily mean they're low quality, but without testing you can't be sure

if they are poor quality and deteriorate under load, they are so hard that the cups/cones could quickly be damaged

just get good quality steel

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by mattr

Which is what most comparable industries do.

Good quality steel is far more suitable for the loads and conditions in cycling than any ceramic bearing.
Any of the claimed benefits either come with significant caveats, or can be achieved by proper selection/specification of steel bearings.

Leave the ceramic stuff for what it's best for.

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by alcatraz

I've tried this stuff and my experience is that the two widely available kinds of ceramic available Ni3H4 and ZRO2 are similar but different.

They are hard but brittle. Ni3H4 more so than ZRO2.

If the ball diameter is small then it can't take a heavy load. At the same diameter ZRO2 can take a bit more weight than Ni3H4.

The only places on the bike I've had ceramic bearings crack is in the rear wheel (my hubs use small 6802 bearings) and my pedals. The two center bearings at axle middle are put under most load. Maybe use like steel bearings in the inner two bearings and ceramic elsewhere.

The balls are simply too small for the load they are put under. As for front wheel and bottom bracket, derailleur pulleys. I havent had much issues with ZRO2 full ceramic bearings.


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