how to install a derailleur on a mountain bike

How to Install a Derailleur on a Mountain Bike

Installing a derailleur on a mountain bike can seem intimidating, especially for those who are new to bike maintenance. However, with the right tools, a little patience, and attention to detail, you can successfully install a derailleur and improve the shifting performance of your bike. This guide will take you through the step-by-step process of installing both a rear and front derailleur on your mountain bike.

Tools Needed

- 5mm Allen wrench - Screwdriver (Philips and flathead) - Chain tool - Ruler or measuring tape - Bike stand (optional but helpful) - Cleaning rag

Step 1 Gather Your Materials

Before you start, ensure you have all the necessary tools and the new derailleur you wish to install. Make sure that the derailleur is compatible with your bike's drivetrain (the number of speeds) and that any additional components like cables and housing are ready for installation.

Step 2 Remove the Old Derailleur

If you are replacing an existing derailleur, you will need to take it off first. Use your 5mm Allen wrench to loosen the bolt that secures it to the derailleur hanger on the rear triangle of your bike frame. Once it’s loose, slide the derailleur off the hanger.

Next, you’ll need to disconnect the derailleur cable. Look for the barrel adjuster where the cable enters the derailleur; you'll typically need to unscrew this to release the cable. If your bike has a front derailleur, repeat the same process for removal.

Step 3 Prepare the New Derailleur

Before mounting the new derailleur, take a moment to ensure it’s clean and free from any debris. You may want to read any specific installation instructions that came with the derailleur. This ensures you’ll know any peculiarities specific to that model.

Start by attaching the rear derailleur to the derailleur hanger. Slide the derailleur in place and tighten the mounting bolt securely using the 5mm Allen wrench. Ensure that the derailleur is aligned properly; it should hang straight down and not be twisted.

Next, thread the chain through the derailleur’s jockey wheels (the small wheels) according to the manufacturer's instructions. You may need to remove a link from your chain using a chain tool if the chain is too long.

Once the chain is correctly routed, you can reattach the derailleur cable. Feed the cable through the housing and tighten it in place. Make sure to leave some tension on the cable by pulling it while you tighten the barrel adjuster.

Step 5 Install the Front Derailleur (if applicable)

For a front derailleur installation, begin by identifying the mounting point, which is usually on the down tube of the frame. If using a braze-on type derailleur, you may need a clamp to attach it securely. Align the derailleur so that the chain will sit correctly on the chainrings, typically 1-3mm above the largest chainring.

Once in position, tighten the derailleur securely. Then, route the cable through the derailleur and adjust the tension as needed – similar to how you did for the rear derailleur.

Step 6 Fine-Tuning and Adjustments

After both derailleurs are installed, you will need to adjust the high and low limit screws. The high limit prevents the chain from shifting beyond the smallest cog or chainring, while the low limit ensures it doesn’t go past the largest cog or chainring. Start with the high limit by shifting into the highest gear and adjusting until the chain is aligned correctly without rubbing.

Next, fine-tune the cable tension by adjusting the barrel adjuster. Shift through all gears to ensure smooth transitions. You may need to make small adjustments, especially if you notice any hesitation or skipping during shifts.

Step 7 Test Ride

Once adjustments are made, take your bike for a test ride. Pay close attention to the shifting performance and make any additional adjustments as necessary. Additionally, check for any unusual noises that might indicate issues in the setup.

Conclusion

Installing a derailleur on a mountain bike doesn’t have to be a daunting task. With a clear understanding of the process and the right tools, you can enhance your bike's functionality and enjoy smoother rides on your trails. Remember, regular maintenance and fine-tuning are key in keeping your cycling experience enjoyable. Happy riding!