how to replace rear derailleur on mountain bike

How to Replace the Rear Derailleur on a Mountain Bike

If you’re an avid mountain biker, you know that maintaining your bike’s performance is crucial for an enjoyable ride. One of the essential components that often requires replacement is the rear derailleur. Whether it’s due to damage, wear, or an upgrade, replacing the rear derailleur is a task that can be done with some basic tools and a little knowledge. Here’s a step-by-step guide to help you through the process.

Tools and Materials You Will Need

Before you begin, gather the following tools

- A new rear derailleur compatible with your bike - A 5mm Allen wrench or screwdriver (depending on your derailleur type) - A chain tool (if you need to remove the chain) - Cable cutter (for cutting the new derailleur cable) - A small flathead screwdriver (for adjusting tension) - A bike stand (optional, but helpful)

Step 1 Remove the Existing Rear Derailleur

Start by shifting your bike into the smallest rear cog. This relieves tension from the derailleur. Next, use your 5mm Allen wrench to remove the bolt securing the derailleur to the derailleur hanger. Carefully detach the derailleur from the hanger. If your derailleur is connected to the chain, you may need to break the chain using the chain tool to remove it completely.

Step 2 Disconnect the Cable

Locate the derailleur cable that runs to the rear derailleur. Using the small flathead screwdriver, loosen the bolt that secures the cable to the derailleur and gently slide the cable out. Be careful not to damage the cable housing as you pull it free.

Step 3 Install the New Rear Derailleur

Now it’s time to install the new derailleur. Position the derailleur on the derailleur hanger, ensuring that the pulley wheels align correctly with the chain path. Use your Allen wrench to secure the derailleur with the bolt; make sure not to overtighten, as this can damage the hanger.

Step 4 Reconnect the Derailleur Cable

Next, take your derailleur cable and thread it through the appropriate cable housing. Pull it through until you have enough slack to attach it securely to the new derailleur. Use the flathead screwdriver to tighten the bolt around the cable, ensuring it is secure but without pinching the cable housing.

Step 5 Adjust the Limit Screws

Before testing your new derailleur, you’ll need to adjust the limit screws. These screws determine how far the derailleur can move in both directions. Shift the chain onto the smallest cog and adjust the “high” limit screw to prevent the chain from falling off. Then, shift the chain to the largest cog and adjust the “low” limit screw accordingly. Proper adjustments ensure smooth shifting and prevent cross-chaining.

Step 6 Fine-Tune the Cable Tension

Use the barrel adjuster located on your shifter or near the derailleur to fine-tune the cable tension. Turning the barrel adjuster clockwise will increase tension, while turning it counterclockwise will decrease it. Test the shifting by riding through the gears to ensure everyone shifts smoothly.

Step 7 Test Ride

After you’ve made all the adjustments, take your bike for a test ride. Pay close attention to the shifting performance. If you notice any skipping or sluggish shifting, return to the cable tension and limit screw adjustments until you achieve optimal performance.

Conclusion

Replacing the rear derailleur on your mountain bike is a manageable task, and doing it yourself can save you time and money. With the right tools, parts, and a little patience, you can ensure that your bike is ready for its next adventure in the great outdoors. Happy riding!