how to change a derailleur on a mountain bike

How to Change a Derailleur on a Mountain Bike

Changing the derailleur on a mountain bike can seem daunting, but with the right tools, some basic knowledge, and a bit of patience, it can be a straightforward process. The derailleur is an essential component of a bike’s shifting system; it moves the chain between gears on the cassette and chainrings. Whether you’re replacing a broken derailleur or upgrading for improved performance, here’s a step-by-step guide to help you through the process.

Tools You Will Need

Before you start, make sure you have the necessary tools - A multi-tool or a set of Allen wrenches - A screwdriver (usually a Phillips head) - A chain tool (if you need to remove the chain) - A new derailleur (make sure it’s compatible with your bike) - Bike stand (optional but recommended) - A clean cloth for maintenance

Step 1 Prepare Your Bike

1. Secure Your Bike Place your bike on a work stand. This will give you the stability you need to work comfortably. If you don’t have a stand, flipping the bike upside down can also work, but it may be less convenient.

2. Shift Gears Before you begin, shift your bike into the smallest chainring and the smallest rear cog. This positions the derailleur in a way that relieves tension, making it easier to remove.

Step 2 Remove the Old Derailleur

1. Disconnect the Chain If your derailleur is connected directly to the chain, use a chain tool to remove the chain link or disconnect the quick link. If you have a traditional chain, you may have to break it to get it free from the derailleur.

2. Unbolt the Derailleur Locate the bolt that attaches the derailleur to the derailleur hanger on the bike frame. Use your Allen wrench or multi-tool to remove this bolt. Be sure to keep it safe for the installation of the new derailleur.

3. Detach the Cable Identify the derailleur cable that shifts gears. Loosen the cable tension by using the appropriate screwdriver, allowing you to detach the cable from the derailleur. Make sure to note how the cable is threaded for easier reinstallation.

4. Remove the Derailleur With the chain disconnected and the cable detached, you can now remove the old derailleur from the hanger.

Step 3 Install the New Derailleur

1. Attach the New Derailleur Position the new derailleur on the derailleur hanger and insert the bolt that secures it to the frame. Tighten it enough to hold it in place but do not over-tighten it just yet; you might want to adjust the position later.

2. Reconnect the Cable Thread the derailleur cable through the appropriate guide and pull it tight. Secure it in place using the tensioning screw. Ensure there’s no slack in the cable but do not overtighten it yet.

3. Reattach the Chain If you disconnected the chain, reattach it to the new derailleur. Make sure the chain runs smoothly through the derailleur’s jockey wheels.

Step 4 Fine-Tune and Adjust

1. Adjust Limits Locate the limit screws on the derailleur. These screws control how far the derailleur can move. Shift through your gears and adjust the screws to ensure the derailleur moves correctly between gears without over-shifting. The high limit screw controls the smallest cog, and the low limit screw controls the largest cog.

2. Fine-Tune Tension Shift through the gears again while adjusting the cable tension if necessary. Achieve a balanced feel where the chain shifts smoothly without hesitation.

3. Test Ride Before you head out for a long ride, take a short test ride to ensure everything is functioning properly. Listen for any unusual noises that may indicate misalignment or tension issues.

Conclusion

Changing a derailleur on your mountain bike requires some mechanical skills, but with patience and the right approach, you can do it yourself. Not only will this save you some money, but it will also help you understand your bike better. Regular maintenance of your derailleur will improve your bike's performance and ensure a smoother ride. Remember, if you're ever in doubt, consult a professional or refer to your bike manual for specific instructions related to your model. Happy cycling!