Mountain bikers often find themselves in a predicament when their beloved bikes start emitting strange noises or rumbling sensations. These issues can be attributed to various factors, but more often than not, the culprit is a bearing that's in dire need of lubrication or replacement. Whether it's a creaking or cracking noise or an intermittent one that appears after a specific duration of riding, servicing the cartridge bearings can be the solution to restore the bike's smooth performance.
Identifying the source of the bearing issue is crucial in determining the appropriate course of action. Bottom brackets are often the prime suspects, but headset bearings, linkage bearings, and hub bearings can also be the cause of the unwanted noises. Unlike hub and bottom bracket bearings, linkage and headset bearings do not fully rotate, often only moving a few degrees under high load. These bearings are prone to accumulating dirt and debris, leading to creaking and groaning if not cleaned and greased regularly.
To service the cartridge bearings, a few essential tools are required, including a grease gun, a Stanley knife with a fresh blade, kerosene, and clean rags. The first step in the process is to remove and clean the bearing. While there are various methods and specialized tools available for bearing removal, the key is to extract the bearing straight to avoid damaging the bearing seat or collapsing the bearing itself.
Once the bearing is removed, the next step is to take off the seals. Using the sharp point of a Stanley knife, carefully insert the blade under the edge of the seal and lift outward. It's important to be gentle to avoid bending the thin steel washer within the seal, as this can hinder the reinstallation process and compromise the seal's effectiveness in keeping water and debris out.
Cleaning the bearing is a crucial step in the servicing process. Soaking the bearing in a jar of kerosene or distillate, or using a heated ultrasonic cleaner, can effectively dissolve old grease and debris from the bearing's inner workings. For severely damaged or seized bearings, removing the bearing and giving it a spin can further free up its internal components.
After cleaning, the bearing needs to be dried thoroughly. Compressed air can be used to blast moisture and debris from the bearing, while drying it in the sun or on a dry cloth is also an option. Once the bearing is dry, it's time to re-pack it with fresh grease. The type of grease used depends on the bearing's application. For load-bearing bearings, a thick, high-temperature waterproof grease is recommended, while a finer synthetic grease like Slickoleum is preferred for bearings that spin, such as those in hubs.
With the bearing re-packed, the seals can be gently pressed back in place using fingers, taking care not to damage them. Any excess grease should be wiped off. Finally, the serviced bearings are ready to be reinstalled following the manufacturer's recommendations, usually with a thin smear of grease to prevent moisture ingress and subsequent creaking and noise.
By following this step-by-step guide, mountain bikers can effectively service their bike's cartridge bearings, eliminating unwanted noises and ensuring a smooth, enjoyable riding experience. Regular maintenance of bearings not only prolongs their lifespan but also saves riders from the hassle of dealing with persistent creaking and rumbling while out on the trails.
