how to install mountain bike derailleur

How to Install a Mountain Bike Derailleur

Installing a mountain bike derailleur may seem daunting, but with the right tools and a bit of patience, you can do it yourself. The derailleur is a critical component of your bike’s drivetrain, allowing you to shift gears smoothly and efficiently. This guide will walk you through the process step-by-step.

Tools Required

Before you start, ensure you have the following tools ready

1. A 2.5mm Allen wrench (or the size that fits your bike’s derailleur) 2. A Phillips screwdriver (if your derailleur uses screws) 3. Chain tool 4. Bike stand or a stable surface to work on 5. Clean rags for lubrication 6. Bike lubricant or grease

Step 1 Remove the Old Derailleur

To install a new derailleur, you need to remove the old one first. Here’s how

1. Shift to the Highest Gear Begin by shifting your bike to the highest gear (smallest chainring in the front and smallest cog in the back). This slackens the chain and makes it easier to remove the derailleur.

2. Disconnect the Chain If your derailleur is threaded onto the chain, use a chain tool to break the chain. Note which links were connected for easy reassembly.

3. Unscrew the Derailleur Locate the mounting bolt on the derailleur. Use your Allen wrench to loosen and remove it. If your derailleur uses screws instead, use the Phillips screwdriver to remove them.

4. Take Off the Cable Use cable cutters or a suitable tool to cut the derailleur cable if it is frayed or needs replacing. Make sure to release any tension before cutting.

Once you have completed these steps, the old derailleur should be completely removed.

Step 2 Prepare the New Derailleur

Before installing the new derailleur, check to ensure it is compatible with your bike's drivetrain. Look for the following

1. Speed Compatibility Ensure the derailleur matches the speed of your shifters (e.g., 9-speed with 9-speed).

2. Mount Type Verify that the mounting bracket and bolt size are compatible with your bike frame.

3. Adjusting Limits Some derailleurs come with factory preset limit screws, but they may need adjusting once installed.

Step 3 Install the New Derailleur

1. Attach the Derailleur Position the new derailleur on the derailleur hanger, ensuring it sits correctly. Secure it by tightening the mounting bolt using the appropriate tool.

2. Connect the Cable Insert the cable through the cable guide and onto the derailleur’s cable anchor point. Pull the cable tight and secure it in place. Make sure to leave a little slack for adjustments.

3. Reconnect the Chain Thread the chain through the derailleur pulleys. If you broke the chain, reconnect it using the chain tool, ensuring it connects correctly. Check that the chain runs smoothly through the derailleur.

Step 4 Adjust the Derailleur

Making precise adjustments is vital for your bike to shift smoothly

1. Limit Screws Adjust the limit screws (if necessary) to ensure the derailleur doesn’t shift the chain off the cog or chainring. The small cog limit is adjusted with the high limit screw, while the large cog is adjusted with the low limit screw.

2. B-tension Adjustment This screw controls the distance of the derailleur from the cogs. The derailleur should sit close enough to shift but not so close that it causes rubbing.

3. Test Shifting Shift through all the gears while turning the pedals. Make minor adjustments as necessary until shifting is smooth in both directions.

Final Steps

Once everything is installed and adjusted, give your bike a clean wipe down, paying attention to the components you’ve worked on. Test ride your bike gently to confirm that the derailleur operates smoothly under load, making any final adjustments as needed.

Conclusion

Installing a mountain bike derailleur can be a rewarding task for any enthusiast. Not only does it give you a better understanding of your bike, but it also enhances your cycling experience with smooth gears. With practice, this process will become easier, and you’ll be able to handle more intricate maintenance tasks on your mountain bike. Happy cycling!