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Cartridge bearings are those little workhorses inside your bike’s hubs that keep your wheels spinning smoothly. Over time, they can wear out or get damaged, leading to a rough ride. But don’t worry! Replacing them is easier than you might think, and you don’t need any expensive, specialized tools to get the job done! With a bit of know-how and some basic tools, you can have your bike spinning smoothly again in no time.
Hub Anatomy: Your Bike’s Spinning Core
Before you jump into the replacement process, it’s helpful to understand the basic anatomy of a bike hub. The hub is the central part of your wheel that allows it to rotate smoothly around the axle.
- The Hub Shell: This is the main cylindrical body of the hub. It houses the bearings and other internal components.
- Bearings & Sleeves: The bearings are press-fit into the hub shell from both sides. An alloy sleeve might be present between the bearings to maintain proper spacing. Dust seals on the outer edges protect the bearings from dirt and debris.
- Axle: The axle runs through the center of the hub and attaches the wheel to your bike. Many modern bikes use thru-axles, which are long, cylindrical shafts that thread directly into the frame or fork.
Step-by-Step Cartridge Bearing Hub Replacement
What you’ll need
- New cartridge bearings (make sure you get the right size for your hub!)
- A homemade bearing press (we’ll show you how to make one)
- Flathead screwdriver
- Mallet or hammer
- Isopropyl alcohol
- Grease
- Rubber-handled tool or pliers (optional)
- Socket or bearing drift (optional)
Removing The Old Bearings
- Access the Inner Race: If your hub has an inner alloy sleeve, you’ll need to carefully move it to one side to access the inner race of the bearing. Use a rubber-handled tool or pliers to gently nudge it without causing any damage.
- Tap Out the Bearing: Use a flathead screwdriver and a mallet to tap the inner race of the bearing from the inside of the hub. Apply force evenly around the bearing, rotating it as you tap to ensure it comes out straight. Avoid hitting one side too hard, as this can damage the hub shell.
- Inspect the Bearings: Once the bearings are out, take a close look at them. If you see any signs of damage, such as rust, pitting, or grit, it’s definitely time for replacements.
Installing New Bearings
- Clean and Grease: Clean the hub shell thoroughly with isopropyl alcohol to remove any old grease or debris. Then, apply a thin layer of fresh grease to the areas where the new bearings will sit. This will help ensure smooth operation and protect against moisture and dirt.
- Build a DIY Bearing Press: You don’t need a fancy bearing press for this job. You can easily create your own using a threaded shaft, washers, and nuts. The shaft should be small enough to fit through the bearings, and the washers should be large enough to cover the hub shell.
- Press in the Bearings: Assemble your homemade press with a nut, washer, the hub, the new bearing, a bearing drift (or a socket that matches the bearing’s outer diameter), another washer, and the outer nut. Start tightening the press gently to make sure the bearing goes in straight. If it starts to go in crooked, adjust it before continuing.
- Seat the Bearings: As you continue tightening the press, you’ll feel resistance. When the resistance suddenly increases, the bearing is fully seated in the hub. Stop tightening at this point to avoid damaging the bearing or hub.
Final Assembly & Extra Tips
- Reinstall the Inner Sleeve: If your hub has an inner sleeve, make sure it’s correctly positioned before inserting the second bearing.
- Grease and Reassemble: Apply a thin layer of grease to the outer surfaces of the bearings and the inner side of the end caps. This acts as an additional barrier against moisture and dirt.
- Reinstall the Wheel: Carefully reassemble the hub and reinstall the wheel onto your bike, making sure to lightly grease the thru-axle before threading it in.
Remember
- Always handle the hub and bearings with care to avoid damage.
- Be mindful of the force you apply when tapping out the old bearings or pressing in the new ones.
- Use the correct size bearings for your hub.
- Don’t be afraid to reach out to your bike shop or the manufacturer’s customer service if you have any questions or concerns.
