Ceramic freehub bearings?

[mythical]

If you ask me, that risk isn’t worth the minute weight savings, let alone the investment. The reason why I wouldn't go full ceramics in the freehub is due to their sensitivity to shocks and impact from sudden peak loads with shifting and hard accellerations. Not only do full ceramic bearings typically have much lower load capacities than its ceramic hybrid or steel equivalent that feature steel races, your rear hub then has a significantly reduced load capacity. The same problem might explain why your steel bearings pitted and failed in the first place.

Also, I have seen what happens when full ceramic bearings shatter upon impact and it isn't pretty. In fact, it might write off the entire rear hub, so unless the bearing is comparatively larger, I wouldn't even dare to think about full ceramic bearings, not for the cassette body either.

There are two common materials for full ceramic bearings: zirconia and silicon nitride (Si3N4). Usually, bearings with zirconia races have a better impact resistance and are also slightly heavier than a silicon nitride one, though weight savings on the bearing alone is quite significant compared to steel or ceramic hybrid. Load capacity is usually even lower than a smaller size of the same series in steel.

[eric]

"ceramic" bearings used in bicycles are almost always hybrid ceramics. Only the balls are ceramic. The races are steel.
Full ceramic bearings are too expensive for anything except specials.

[PLuKE]

If you ask me, that risk isn’t worth the minute weight savings, let alone the investment. The reason why I wouldn't go full ceramics in the freehub is due to their sensitivity to shocks and impact from sudden peak loads with shifting and hard accellerations. Not only do full ceramic bearings typically have much lower load capacities than its ceramic hybrid or steel equivalent that feature steel races, your rear hub then has a significantly reduced load capacity. The same problem might explain why your steel bearings pitted and failed in the first place.

Also, I have seen what happens when full ceramic bearings shatter upon impact and it isn't pretty. In fact, it might write off the entire rear hub, so unless the bearing is comparatively larger, I wouldn't even dare to think about full ceramic bearings, not for the cassette body either.

There are two common materials for full ceramic bearings: zirconia and silicon nitride (Si3N4). Usually, bearings with zirconia races have a better impact resistance and are also slightly heavier than a silicon nitride one, though weight savings on the bearing alone is quite significant compared to steel or ceramic hybrid. Load capacity is usually even lower than a smaller size of the same series in steel.

I have been advised to use a hybrid and full ceramic on the freehub. I know ceramic isn't good for shocks I try to avoid as much bad tarmac as possible. But I understand what your saying.

Thank you.

Luke

[PLuKE]

"ceramic" bearings used in bicycles are almost always hybrid ceramics. Only the balls are ceramic. The races are steel.
Full ceramic bearings are too expensive for anything except specials.

These bearings are non bicycle specific and are ceramic balls and races, as the seals act as a race. They spin very well indeed.

I had my Campy bearings taken out for some higher grade SS bearings and they was lovely, again there non bicycle specific ones, but i did notice that the ceramics are faster and spin better for the same given effort in my mind, that could well be a placebo which is fine, as I know I have the best bearing type, and make me push harder.

Thanks
Luke

[ichobi]

If you have your own personal mechanic and dont mind checking in with them monthly, or can fix your own stuff ceramic bearings can be a headache. When properly maintained they feels great to ride with. So smooth


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[mythical]

A cheap and excellent hack: replace one ball in a steel cartridge bearing with ceramic one. The ceramic ball smashes grit that contaminates a bearing and smoothens the contact surfaces of the races. It'll easily increase bearing life by double. The main drawback: it requires dis- and reassembly.

[eric01]

That's a clever idea. Is that a hybrid-hybrid ceramic bearing then?