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Comment by buro9 | Hacker News Reader

Having been dumb enough to use ceramic bearings in a BMX bottom bracket, and in the hubs of a mountain bike... I would not purchase this system.

The replacement rate for those bearings would be astonishing.

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You fell victim to marketing. Full ceramic bearings tend to shatter. They aren't suitable for high impact applications, and just plain expensive for everything else. Hybrid ceramic bearings (ceramic balls, steel races) are cheaper, but the races will wear out at the rate of steel, so they are an expensive option that needs to be maintained.

Your best value if you want fast bearings is to clean out the grease and replace it with something lighter like sewing machine oil or Bones speed cream. The downside is that you have to maintain it more often because oil doesn't stick around as long as grease does.

Also, the difference between ceramic and regular bearings is on the order of 1 watt. You'd save way more time in a BMX race by wearing tighter fitting clothes, and if you are doing tricks instead of racing then ceramic bearings on a BMX bike makes no sense.

In my defence I did not pay for those components :) These were companies seeking my endorsement, and I like to put such components to use in the way I enjoy rather than the way they hope.

Care to expand this comment? Do ceramic bearings have a higher wear-rate than a traditional steel ball bearing?

Much lower wear and slightly less friction. But they cost roughly 10x as much going from a quality steel bearing. They are marketed as being faster but it's not noticeable in real world conditions. They might be worth it in some non-cycling applications (high precision motors or something). They also break if abused. Steel bearings might deform the balls or dent the race, but they will still turn.

However, as long as there are people with $250 to spend someone will make a $250 set of bearings- don't forget to lube them with snake oil for the fastest results.

Hambini has a good article on this[1]. The basic problem (apart from cost) is that only the ball bearing itself is ceramic; the inner and outer races are made of steel and the ball wears a groove into them which increases friction over time. Near the bottom of the article there's a 'power consumption vs kilometres' chart which illustrates this nicely.

"Hybrid ceramic bearings are the equivalent of trying to run a locomotive on an asphalt road - the hardness differential causes the road (raceway) to become damaged."

[1] https://www.hambini.com/blog/post/ceramic-bearings-vs-steel-...

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