Wheel bearings are small metal rings whose purpose is to keep your motorcycle’s wheels rotating smoothly. Although small, they play a crucial role in the safety and smoothness of your ride. Wheel bearings wear down over time, and it’s important to know when it’s time to part ways with your current ones, and get new ones. Furthermore, it’s important to know what to look for when buying these new ones, as they’re not a one-fits-all solution. Let’s discuss these Motorcycle Parts in detail so you can shop for replacement bearings with confidence.
What Are They?
Wheel bearings, as aforementioned, are small metal rings or races that hold tiny metal balls. The assembly of races and balls make up the bearing which allows wheels to spin smoothly by minimising friction. Besides a smooth rotation, wheel bearings also take up the weight of the motorcycle and are located inside the wheel hub, which is the part that connects wheels to axles. Generally, front and wheel bearings are similar and work similarly, but they can be different in size and construction.
Types of Bearings
Just like most Motorcycle Parts, bearings come in a variety of shapes and sizes, and they can be made using different materials. Since bearings are important components that ensure the wheel, tyre and hub assembly work together properly, it’s important you get the right ones. Both wheels have their own set of bearings, and they can be different.
Ball bearings are the most common type of bearings used in most vehicles. They’re made up of round metal balls that allow the bearing to spin in both directions. Ball bearings are capable of withstanding radial loads, as well as axial and thrust loads. The spherical balls in these bearings feature a smaller contact area that limits them to specific applications and types of vehicles, as they’re not capable of withstanding heavy impacts and shocks.
These bearings feature a rolling element that utilises a cylinder rather than a ball. As a result, they feature cylindrical metal rollers that are enclosed by outer and inner races. The rollers also feature a constant diameter across the length, which basically allows them to spread the load across a wider point of contact. This makes them more capable than ball bearings, thus more suitable for heavy-duty applications. The one area they struggle in is handling axial loads, so avoid using them in non-cornering wheels.
Tapered Roller Bearings
These bearings are similar to roller bearings, but as their name implies, they’re tapered and placed at a specific angle. Due to their unique geometrical design, they can withstand both combined and axial loads pretty well. They feature a cone-shaped assembly that helps them reduce friction while cornering. So, when you corner, the wheels tilt at an angle depending on the weight placed on them. As a result, they provide a smooth operation and prevent shifting parts from grinding.
Stainless Steel vs Ceramic Bearings
Bearings are typically made of either stainless steel or ceramic. Stainless steel is a popular material as it’s rust- and corrosion-resistant. Plus, it lasts a long time without needing lubrication, and is capable of withstanding high temperatures. On the other hand, ceramic bearings are self-lubricating and last longer than their stainless steel counterparts. They’re very tough and reduce the rolling resistance significantly. As a result, the driveline doesn’t take as high loads. However, ceramic bearings are more expensive, which is why they’re generally used for racing purposes.
Bearing Kit vs Individual Bearing
Wheel bearings can be purchased as kits and single units. The kits come with other parts such as protectors, covers, O-rings, spacers, lock nuts and split pin sealers. Single unit bearings just contain the bearing. So, if you’re looking to restore your entire wheel bearing assembly, you’ll probably need a kit. Otherwise, just the bearing will do, saving you money in the process.
Make sure the bearings you buy are compatible with your motorcycle. This includes the load-carrying capacity the bearing is rated for, which you can find on the user manual of your bike.
When to Replace Them?
The life of your bearings will depend on a few factors, including manufacturer, driving conditions, loads, maintenance, etc. Generally, however, they are expected to last anywhere between 120.000 to 150.000km. Some of the warning signs for a failing bearing include:
Unusual sounds from the wheels – The bearings can fail even without any signs. if you’re lucky, however, you’ll at least hear some unusual noises coming from your wheels. Failing bearings will make grinding noises that are the result of worn-out metal balls, rollers or lack of lubrication.
Uneven tyre wear – When bearings wear out, they make the wheels loosen up. As a result, the wheels will wobble and wear your tyres unevenly. Check for signs of uneven tyre wear when performing maintenance.
Steering vibration – If you feel vibrations when steering your motorcycle, a bearing may be faulty.