What are bearings?
Bearings are highly engineered, precision-made components that enable machinery to move at extremely high speeds and carry remarkable loads with ease and efficiency. The allow your pedals and cranks to rotate, wheels to roll, and handlebars to steer. They are sometimes even found in your derailleur too. Bearings must be able to offer high precision, reliability and durability, as well as the ability to rotate at high speeds with minimal noise and vibration. Bearings are found in applications ranging from automobiles, airplanes, construction equipment, power tools, electronics, and toys. If something twists, turns or moves, it probably has a bearing in it.
What are the different types?
There are many different types of bearings, but the two main types we work with in the cycling industry are “loose ball” and sealed”. The loose ball bearings are steel balls sitting in a carrier that have no direct seal and relies on the component it is installed in to seal itself. These loose ball bearings are inexpensive to manufacture, which in turn creates a very inexpensive product for the consumer.
A sealed bearing is much more common in quality bicycle components. A sealed bearing is designed to be a completely sealed cartridge which houses the steel (or stainless steel or ceramic) balls which you can not see. It is kind of like a cassette tape in the sense that the cassette tape real can move inside the housing but you can not directly touch it. These sealed bearings are the best for all bicycle components because they require less adjustment over their life span and when they do wear out, it will not wear out the component it is housed in… unless you ride the bearing until it disintegrates which is a candidate for a worn out component as well.
Why do they need to be replaced?
A bearing it will wear after many hours and miles due to load distribution and heat. This means that a worn bearing will create more friction. In the cycling world, friction is our enemy. It will slow you down and cause unwanted noises and if not addressed will become a safety concern as well.
When do bearings need to be replaced?
As for bicycles, there are a few main areas that need to be checked periodically for bearing concerns. These areas are the hubs (at the middle of the wheels), headset (this makes your handlebars turn), and the bottom bracket (this makes your cranks turn). Being that we live in a dry climate, the grease dissipates over time so these components need to be removed from the bike, cleaned, inspected, and if they look good, they will be reinstalled with the application of new grease. These services are recommended to be done once a year. With pressfit bottom brackets we tend to see an eight month interval because of its simplified design.
Bearings, they make the world move. From heavy industrial machinery with bearings the size of a car to very small bearings inside of toys the size of your thumb nail, none of our transportation options would be possible without bearings.