This is mostly due to the additional time spent to perfect a quality ceramic ball.
Ceramic vs steel bearings bike.
On a bicycle which is considered a low speed application compared to a formula 1 car or motorcycle engine for example the ball bearing material itself steel or ceramic has little to no effect on the friction of the bearing assembly.
The ceramic balls are often silicon nitride or equivalent.
Cost of purchase for ceramic and steel bearings.
The material can be polished smoother than any metal reducing friction and wear.
Steel bearings are commodity items that are composed of hardened steel balls and a steel inner and outer race.
A ceramic bearing is also harder than steel bearings up to 30 which improves durability and they also don t rust so less maintenance should be required.
When a bike with ceramic bearings goes over a bump the ball bearing which is harder than the steel race that contains it strikes the inner surface of the race.
Most sealed ceramic bearings are actually hybrid ceramic bearings which combine a steel race with ceramic ball bearings.
The first thing that strikes the eye when looking at bicycle bearings is the difference in price between steel bearings and hybrid ceramic bearings.
Geometrically the contact points inner and outer dimensions and thickness between steel and ceramic bearings is the same so they are interchangeable.
The folks at enduro bearings argue that for bicycles the materials are far more important than abec ratings and that for most applications abec 3 and 5 are appropriate for all things bicycle.
In our higher end cult bearings ceramic balls and races lighter lubrication is needed so they roll much quicker with less drag than standard steel bearings.
Ceramic bearings vs steel bearings ceramic materials offer superior corrosion and heat resistance higher dimensional stability and lower density which facilitates high speed.
Steel bearings the silicon nitride used in kogel ceramic bearing balls has a set of material properties making them perfect for bicycle wheel bearings.