Shimano Brakes Not Bedding In? Here’s How to Fix It
Are your Shimano brakes feeling weak and spongy? Are you struggling to get them to bed in properly? It’s a frustrating problem, but don’t worry, you’re not alone. Many cyclists experience this issue. This article will guide you through the common causes and solutions to get your brakes working effectively.
Understanding Brake Bedding
Brake bedding is the process of transferring a thin layer of brake pad material onto the rotor. This creates optimal friction for strong and consistent braking. When brakes aren’t properly bedded in, you’ll experience reduced stopping power and increased brake noise. Bedding in your brakes ensures they perform as intended.
Common Causes of Poor Brake Bedding
- Contamination: Oil, grease, or other contaminants on the pads or rotors significantly reduce friction.
- Glazed Pads: Overheating can cause the brake pads to glaze over, creating a smooth, hard surface that doesn’t grip well.
- Incorrect Bedding Procedure: Not following the proper bedding-in technique can result in inadequate material transfer.
- Rotor Issues: New rotors sometimes have a protective coating that needs to be removed.
- Pad and Rotor Compatibility: Some pad materials may not be ideal for certain rotor types.
Troubleshooting and Solutions
Let’s dive into the specific steps you can take to diagnose and fix your Shimano brakes.
1. Cleaning the Rotors and Pads
This is often the first and most crucial step. Contamination is a common culprit.
- Rotor Cleaning: Use isopropyl alcohol (IPA) or a dedicated brake cleaner on a clean cloth to thoroughly clean the rotors. Wipe until no more residue appears.
- Pad Cleaning/Replacement: If the pads are contaminated, you might try sanding them down with sandpaper to remove the top layer. However, heavily contaminated pads are best replaced.
2. Bedding-In Procedure
Follow this process carefully to ensure proper material transfer:
- Find a safe, flat area where you can ride at a moderate speed.
- Accelerate to a moderate speed (e.g., 10-15 mph).
- Apply both brakes firmly and evenly, slowing down to a near stop (but don’t come to a complete stop).
- Repeat this process 10-15 times. Focus on using the front brake more to bed it in.
- Let the brakes cool down completely.
- Repeat the process again, but this time with slightly harder braking.
Important: Avoid locking up the wheels during the bedding process, as this can create uneven pad deposits.
3. Addressing Glazed Pads
If your pads are glazed, you’ll need to remove the glazed surface:
- Sanding: Use medium-grit sandpaper to lightly sand the surface of the pads. This will roughen them up and expose fresh material.
- Consider Replacement: If the glazing is severe, replacing the pads is the best option.
4. Checking for Rotor Issues
Inspect your rotors for any signs of damage or excessive wear.
- Cleanliness: Ensure the rotors are free of any coatings or residue.
- Trueness: Check for any warps or bends. A warped rotor can cause inconsistent braking and noise.
- Wear: If the rotors are excessively worn, they should be replaced.
5. Hydraulic Brake Considerations
If you have Shimano hydraulic brakes, several other factors could be contributing to poor performance:
- Air in the System: Air bubbles in the brake lines can cause a spongy lever feel and reduced braking power. Bleeding the brakes is necessary to remove the air.
- Lever Travel: Excessive lever travel can indicate worn pads or low fluid levels.
- Piston Movement: Ensure the brake pistons are moving freely and evenly. Sticking pistons can prevent the pads from contacting the rotor properly.
6. Mechanical Brake Considerations
If you have Shimano mechanical disc brakes, consider the following:
- Cable Tension: Ensure proper cable tension for optimal brake engagement.
- Cable Condition: Check for frayed or damaged cables that may hinder performance.
- Caliper Adjustment: Verify the caliper is properly aligned with the rotor.
When to Seek Professional Help
If you’ve tried all the above steps and your brakes still aren’t performing well, it’s time to consult a professional bike mechanic. They have the expertise and tools to diagnose and fix more complex brake issues. They can also help you choose the right pads and rotors for your riding style and bike.
Prevention
Regular maintenance is key to keeping your Shimano brakes in top condition:
- Clean your rotors regularly.
- Inspect your brake pads for wear.
- Replace worn pads promptly.
- Bleed your hydraulic brakes as needed.
By following these tips, you can ensure your Shimano brakes are properly bedded in and provide reliable stopping power for years to come.
