how to replace a rear derailleur on a mountain bike

How to Replace a Rear Derailleur on a Mountain Bike

Replacing a rear derailleur on a mountain bike may seem daunting, but with the right tools and steps, you can do it efficiently at home. The rear derailleur is responsible for shifting the chain between gears on the rear cassette, so its proper functioning is crucial for optimal performance. Let’s walk through the process step by step.

Tools Required

Before you start, gather the necessary tools - A 5mm Allen wrench (or the specific size based on your derailleur) - A screwdriver (if needed for cable clamps) - Chain tool (if you're removing/replacing the chain) - Pliers (for handling cables) - New rear derailleur - Optional bike stand (for easier access)

Step 1 Remove the Old Derailleur

1. Shift the Gears Start by shifting your bike to the smallest chainring in the front and the smallest cog at the back to relieve tension on the derailleur. 2. Disconnect the Cable Use pliers to carefully loosen the bolt that clamps the derailleur cable in place. Slide the cable out of the clamp. Make sure to remember how it is threaded.

3. Unbolt the Derailleur Locate the mounting bolt holding the derailleur to the derailleur hanger and use the 5mm Allen wrench to remove it. Be cautious to keep the bolt safe for reinstallation or replacement.

4. Take Out the Derailleur Once unbolted, remove the derailleur from the hanger. You might need to disconnect it from the chain if it doesn’t slide out easily.

1. Attach the New Derailleur Position the new derailleur onto the derailleur hanger and insert the mounting bolt. Secure it snugly with the Allen wrench, making sure it’s aligned properly.

2. Reconnect the Chain If you removed the chain, thread it through the new derailleur’s jockey wheels, ensuring it’s properly seated in the path as per the manufacturer’s design.

3. Attach the Cable Thread the derailleur cable back through the clamp, making sure to follow the correct routing and tension preferences. Tighten the clamp securely.

Step 3 Adjust the Derailleur

1. Set the Limit Screws Most derailleurs have limit screws that prevent the chain from going beyond the smallest and largest cogs. Adjust these screws until the derailleur moves smoothly across the gears without overshifting.

2. Test the Shifting Shift through the gears to ensure everything is functioning correctly. Make fine adjustments to the tension of the cable by using the barrel adjuster if necessary.

Step 4 Final Checks

Take the bike for a short test ride to ensure the shifting is smooth and responsive. Listen for any unusual noises, indicating misalignment or additional adjustments needed.

Conclusion

With a bit of patience and the right approach, replacing the rear derailleur on your mountain bike can be a straightforward task. Regular maintenance and timely replacements will keep your bike in top shape, ensuring an enjoyable ride every time.