How to Adjust Shimano Hydraulic Disc Brake Lever Travel

Shimano hydraulic disc brakes are widely used in bicycles due to their effective stopping power and reliability. One crucial aspect of these brakes is the brake lever travel, which refers to the distance the lever moves before engaging the brake pads. Proper adjustment of the brake lever travel is essential for optimal braking performance and rider comfort.

Understanding Brake Lever Travel

Brake lever travel is the distance the brake lever moves from its initial position to the point where the brake pads make contact with the rotor. This travel can be adjusted to suit the rider’s preferences and ensure responsive braking. Shimano hydraulic disc brakes offer two main types of adjustments for brake lever travel: free stroke and reach adjustment.

Importance of Proper Brake Lever Adjustment

Correctly adjusting the brake lever travel is crucial for several reasons:

Safety: Excessive lever travel can lead to reduced braking power and increased stopping distances, compromising the rider’s safety.
Comfort: Adjusting the reach ensures that the brake levers are within comfortable reach of the rider’s fingers, reducing fatigue and strain.
Performance: Optimal brake lever travel allows for quick and precise braking, enhancing the overall riding experience.

Tools and Preparations for Adjusting Brake Lever Travel

Before adjusting the brake lever travel on your Shimano hydraulic disc brakes, it’s important to gather the necessary tools and take some safety precautions.

Necessary Tools

To adjust the brake lever travel, you will need the following tools:

2mm Allen key (for free stroke adjustment)
2.5mm Allen key (for reach adjustment)
Gloves (to protect your hands from brake fluid)
Clean cloth or paper towels

Safety Precautions

When working with hydraulic disc brakes, it’s crucial to take the following safety measures:

Avoid getting brake fluid on your skin or eyes, as it can cause irritation. Wear gloves and safety glasses for protection.
Do not operate the brake lever when the wheel is removed, as this can cause the brake pads to overextend and damage the system.
Ensure the bike is in a stable position, such as on a repair stand or upside down with the saddle and handlebars resting on the ground.

Step-by-Step Guide to Adjusting Shimano Hydraulic Disc Brake Lever Travel

Shimano hydraulic disc brakes offer two types of adjustments for brake lever travel: free stroke and reach. Here’s a step-by-step guide on how to perform these adjustments.

Free Stroke Adjustment

Free stroke refers to the initial travel of the brake lever before the pads make contact with the rotor. To adjust the free stroke:

Locate the free stroke adjustment screw on the brake lever body, usually marked with “S” or “ST”.
Using a 2mm Allen key, turn the screw clockwise to reduce the free stroke or counterclockwise to increase it. Make small increments of 1/8th to 1/4th of a turn.
Test the brake lever feel after each adjustment until you achieve the desired free stroke.

Note: Some Shimano models, such as the 105 R7020, do not have a free stroke adjustment feature.

Reach Adjustment

Reach adjustment changes the distance between the brake lever and the handlebar. To adjust the reach:

Locate the reach adjustment screw, usually found at the top or front of the brake lever body.
Using a 2.5mm Allen key, turn the screw clockwise to bring the lever closer to the handlebar or counterclockwise to move it away. Adjust in small increments to find the most comfortable position.
Test the brake lever feel and repeat the adjustment if necessary.

Checking and Testing the Adjustment

After adjusting the free stroke and reach, it’s essential to test the brakes and ensure proper function:

Squeeze the brake lever firmly and observe the lever travel. The lever should engage the brake pads quickly and provide a firm, responsive feel.
Spin the wheel and apply the brakes to check for any rubbing or uneven pad contact. Make further adjustments if needed.
Take the bike for a short test ride in a safe area to evaluate the braking performance and lever feel under real-world conditions.

Troubleshooting Common Issues

Despite proper adjustment, you may encounter some issues with your Shimano hydraulic disc brakes. Here are two common problems and their solutions.

Excessive Lever Travel

If you experience excessive brake lever travel even after adjusting the free stroke and reach, it may indicate the presence of air in the brake system. In this case:

Check the brake fluid level in the reservoir. If it’s low, add more fluid and see if the issue persists.
If the fluid level is adequate, you may need to perform a brake bleed to remove any air bubbles from the system. Consult Shimano’s technical documents or seek assistance from a professional mechanic.

Uneven Lever Travel Between Brakes

If you notice a significant difference in lever travel between your front and rear brakes, it may be due to:

Uneven pad wear: Inspect the brake pads and replace them if they are worn unevenly or below the minimum thickness.
Caliper alignment: Check that the brake calipers are properly aligned with the rotors. Adjust the caliper position if necessary.
Reach adjustment: Ensure that the reach adjustment is set equally for both brake levers. Use a measuring tool to verify the distance between the levers and the handlebars.

Maintenance Tips for Shimano Hydraulic Disc Brakes

To keep your Shimano hydraulic disc brakes performing at their best, regular maintenance is crucial. Here are some key maintenance tasks to consider.

Regular Brake Pad Replacement

Brake pads wear down over time, affecting braking performance. To replace the pads:

Remove the wheel and locate the brake caliper.
Push the pistons back into the caliper using a flat tool, making space for new pads.
Remove the retaining clip or pin holding the pads in place.
Replace the old pads with new ones, ensuring they are compatible with your brake model.
Reinstall the retaining clip or pin and remount the wheel.

Mineral Oil Replacement

Shimano hydraulic disc brakes use mineral oil as the braking fluid. Over time, the oil can become contaminated, reducing braking performance. To replace the mineral oil:

Consult Shimano’s technical documents for the specific procedure for your brake model.
Drain the old mineral oil from the system and dispose of it properly.
Refill the system with new, high-quality mineral oil, taking care to avoid introducing air bubbles.
Bleed the brakes to ensure optimal performance.

Brake Bleeding Procedure

Brake bleeding is necessary to remove air bubbles from the brake system. The general process involves:

Attaching a bleed funnel to the brake lever and a bleed bottle to the caliper.
Filling the funnel with mineral oil and slowly pumping the brake lever to push air bubbles out of the system.
Closing the bleed port on the caliper and removing the bleed funnel and bottle.
Testing the brakes for proper function and lever feel.

Consult Shimano’s technical documents or a professional mechanic for the specific bleeding procedure for your brake model.

Conclusion

Summary of Key Points

– Shimano hydraulic disc brakes offer free stroke and reach adjustments for customizing brake lever travel.
– Proper brake lever adjustment is essential for safety, comfort, and performance.
– Free stroke adjustment changes the initial travel before pad contact, while reach adjustment modifies the distance between the lever and handlebar.
– Excessive lever travel may indicate the need for a brake bleed or fluid top-up.
– Regular maintenance, including brake pad replacement, mineral oil changes, and brake bleeding, is crucial for optimal performance.

Final Tips for Optimal Brake Performance

To ensure the best performance from your Shimano hydraulic disc brakes:

Familiarize yourself with the specific adjustment and maintenance procedures for your brake model by referring to Shimano’s technical documents.
Regularly inspect your brakes for wear, damage, or leaks, and address any issues promptly.
Use only genuine Shimano parts and high-quality mineral oil for replacements and maintenance.
When in doubt, consult a professional bicycle mechanic for assistance to ensure the safety and reliability of your brakes.

By understanding how to adjust and maintain your Shimano hydraulic disc brakes, you can enjoy consistent, reliable braking performance and a safer, more comfortable riding experience.