Let's face it: ceramic bearings are not for everyone. Some people still believe the durability of ceramic bearings is bad, some don't want to spend any money and some just want things to stay the way they always have been.
To give you some baggage in understanding the benefits of ceramic bearings, we will list the positives and warn for a few potholes in selecting the best bearings for your bicycle.
Rounder and smoother
The number one reason why ceramic bearings work well, is because Silicon Nitride (the material that the balls are made off) can be made with much more accuracy than steel. The balls can be rounder and polished to be smoother than any metal. It is not hard to understand how a rounder and smoother ball will be easier to roll.
The pitfall is that making something this accurate is a time consuming and therefore expensive process. If you find cheap ceramic bearings, they are probably cheap because the manufacturer cut a few corners.
- cutting corners in bearing production can cause all kinds of problems. Most of them leading to the same result: bearing failure.
less compression, leading to less drag
An often heard reason to not buy ceramic bearings is that nothing on a bicycle spins fast (at least compared to a Nascar engine or dentist drill) and therefore the benefits are lost.
In my eyes, and I must admit I have absolutely no data to back this up, the main benefit of Silicon Nitride is that it does not compress under heavy load. Steel is a more flexible material than Silicon Nitride, therefore it compresses more once you put a large load on it, like when you get out of the saddle for a sprint.
Imagine taking a tennis ball and squashing it between your flat hand and a table. Now start rolling it. The ball is flat, has an increased contact area with both your hand and the table. This causes higher drag than trying to roll the ball without a load.
Now imagine replicating the same test with a wooden ball. It will not compress under load and roll easier than the tennis ball. The tennis ball represents steel, the wooden ball represents ceramic if that was not clear.
- Compressing a tennis ball is an easy analogy to understand why a non-elastic material like Silicon Nitride Ceramics cause a reduction in friction.
Although ceramic materials can be damaged, it typically has a longer life span than a steel ball due to the hardness of the material. This only translates to an entire bearing if the races are hardened to a point that they can handle the additional pressure of working together with the ceramic balls.
Again, many opportunities for rogue manufacturers to save costs and offer you a failing product: cutting steps out of the hardening process for the races, making balls that are too brittle or simply not following tight tolerances when it comes to roundness. I have compared ceramic bearings to carbon frames before: The good one and the counterfeit may look the same on the outside, but the truth will surface after a month of use. Buy your bearings from a brand you trust and not from Ebay, just because it says 'ceramic'.
After spending a good chunk of money on premium bearings, it is only fair that you expect a premium service from the company. When you buy the cheapest products, there’s a good chance you will be forking out more money if things go wrong. Buying from a renowned brand you should expect quick answers to your questions. Check the manufacturer website for tech docs and manuals. Maybe even test all this up front as part of your buying process. A company that does not return your calls when you are ready to buy is most likely not going to pick up the phone if you call with a warranty claim.
I hope these were a couple of good tips to help you on your way to finding the best bearings for your ride, whether that is a ceramic or a steel one.