How to Bleed and Maintain Your Shimano SM-RT900 Hydraulic Disc Brakes

Posted on
in No category

Hydraulic disc brakes are an essential component of any road bike, providing superior stopping power and control, especially in challenging conditions. The Shimano SM-RT900 [paid link] hydraulic disc brakes are no exception, offering smooth, reliable braking performance. However, like all hydraulic systems, regular maintenance and proper bleeding are crucial to ensure the brakes function at their best. This guide will walk you through the process of bleeding and maintaining your Shimano SM-RT900 [paid link] hydraulic disc brakes to keep them in peak condition.

Tools Required

  • Shimano brake fluid (Mineral Oil [paid link])
  • Shimano bleed kit [paid link] (including syringe, hose, and stopper)
  • 8mm wrench
  • T10 and T25 Torx wrenches
  • Allen keys [paid link] (5mm, 6mm)
  • Clean, lint-free rags
  • Brake fluid catch container
  • Isopropyl alcohol (for cleaning)
  • Rubber gloves
  • Bike stand [paid link] or a suitable mounting setup

Understanding the Bleeding Process

Bleeding your Shimano SM-RT900 [paid link] hydraulic disc brakes is a vital maintenance task that ensures the braking system remains responsive and free of air bubbles. Air in the brake lines can cause spongy brakes, reduced stopping power, and an overall compromised braking experience. The bleeding process removes air from the brake fluid and ensures that the hydraulic fluid flows smoothly through the brake system.

Why Bleed Shimano SM-RT900 Brakes?

The Shimano SM-RT900 disc brakes use hydraulic brake fluid to transfer force from the brake lever to the caliper. Over time, air can enter the system due to a variety of reasons, including a recent brake pad change, crash, or wear and tear on the brake lines. When this happens, the brake system loses its effectiveness, and the lever may feel spongy or unresponsive. Bleeding the brakes restores the hydraulic pressure and ensures that the brakes function as intended.

Step-by-Step Guide to Bleeding Shimano SM-RT900 Disc Brakes

Follow these steps to bleed your Shimano SM-RT900 hydraulic disc brakes:

1. Prepare the Bike and Workspace

  • Secure the bike in a stand, ensuring it is stable and at a comfortable working height.
  • Remove the wheel to gain easy access to the brake caliper.
  • Clean the brake caliper and lever area to ensure no dirt or debris enters the system during the process.
  • Put on rubber gloves to protect your hands from brake fluid.

2. Attach the Syringe and Brake Fluid

  • Remove the brake lever reservoir cap using a T10 Torx wrench [paid link].
  • Insert the bleed syringe filled with Shimano mineral oil [paid link] into the brake lever reservoir. Ensure the syringe is securely connected and that no air is trapped in the syringe.
  • Open the brake caliper’s bleed port (usually on the side of the caliper) using a T25 Torx wrench [paid link].
  • Attach the second syringe to the caliper’s bleed port.

3. Start the Bleeding Process

  • Slowly depress the brake lever to push the brake fluid into the brake system. This forces the fluid from the brake lever syringe to the caliper, flushing out any air.
  • While applying pressure to the brake lever, watch for air bubbles in the fluid as it moves through the syringes. The goal is to push out all the air trapped in the system.
  • Continue this process until you see a steady stream of brake fluid without any air bubbles coming out of the caliper.

4. Seal the System

  • Once no air bubbles are visible, close the bleed port on the caliper tightly with a T25 Torx wrench [paid link].
  • Slowly release the brake lever and remove the syringe from the brake lever reservoir.
  • Tighten the brake lever reservoir cap to prevent any fluid leaks.

5. Clean Up and Test the Brakes

  • Use a clean rag to wipe any excess brake fluid from the brake system, caliper, and surrounding areas. Brake fluid is corrosive, so make sure to clean up thoroughly to prevent damage to your bike frame or paint.
  • Reinstall the wheel, making sure it is aligned properly.
  • Test the brake lever by squeezing it a few times. The lever should feel firm and responsive. If it still feels spongy, repeat the bleeding process to ensure all air has been purged from the system.

Regular Maintenance for Shimano SM-RT900 Hydraulic Disc Brakes

Proper maintenance of your Shimano SM-RT900 hydraulic disc brakes ensures long-lasting performance and safety. Here’s a breakdown of the essential maintenance tasks to keep your brakes running smoothly.

1. Inspect Brake Pads Regularly

  • Check the thickness of the brake pads regularly to ensure they aren’t worn down excessively. Shimano recommends replacing the brake pads when they have less than 1mm of material left.
  • Clean the brake pads using a clean rag and isopropyl alcohol to remove any dirt or oil buildup that may compromise braking performance.

2. Check Brake Fluid Level

  • Periodically inspect the brake fluid level [paid link] in the lever reservoir. If the fluid level [paid link] drops too low, it can introduce air into the system, leading to reduced performance. If necessary, top up the brake fluid using Shimano mineral oil [paid link].

3. Brake Rotor Care

  • Inspect the brake rotors for any warping or damage. A warped rotor can cause uneven braking, resulting in noise and reduced performance.
  • Clean the rotors using a clean rag and isopropyl alcohol. Avoid touching the braking surface with your fingers to prevent oil contamination.

4. Keep the System Free of Contaminants

  • Avoid getting brake fluid on your rotors or brake pads, as it can drastically reduce braking performance. If you do get brake fluid on these parts, clean them immediately with isopropyl alcohol.
  • If you notice any squealing or rubbing noises, inspect the pads and rotors for contamination and replace them as needed.

5. Monitor for Leaks

  • Occasionally check for leaks around the caliper, brake lever, and brake lines. If you spot any leaks, address them immediately by tightening fittings or replacing damaged parts. Leaks can compromise brake performance and may require additional bleeding.

Conclusion

By following the steps outlined in this guide, you can ensure your Shimano SM-RT900 hydraulic disc brakes remain in optimal condition for consistent, reliable braking performance. Regular bleeding, maintenance, and inspection of brake pads, fluid levels, and rotors are essential practices for maintaining peak performance. Keeping your brakes in top shape will not only enhance your safety but also contribute to a smoother and more enjoyable riding experience.