how to adjust back derailleur on mountain bike

How to Adjust the Back Derailleur on a Mountain Bike

Properly adjusting the back derailleur on your mountain bike is essential for ensuring smooth gear shifts and optimal performance while riding. If your bike is struggling to shift up or down the cassette, or if you're hearing strange noises when changing gears, it may be time for an adjustment. This guide will walk you through the step-by-step process to adjust your back derailleur, helping you restore your bike's shifting capabilities.

Tools You’ll Need Before you start, gather the following tools - A Phillips or flat-head screwdriver - A 5mm Allen wrench (for adjusting the derailleur) - Chain lubricant - A pair of pliers (optional, for fine-tuning)

Step 1 Inspect the Derailleur Before making any adjustments, conduct a thorough visual inspection of the derailleur. Look for any obvious damage, such as bent hangers or a misaligned derailleur cage. If you notice any significant damage, it might need replacing rather than adjustment. Additionally, check the chain and cassette for wear, as these can also affect shifting performance.

Step 2 Check Cable Tension Cable tension is a critical factor in proper shifting. To check this, shift your bike into the highest gear (smallest cog at the back). Observe the derailleur movement; it should position itself directly under the smallest cog. If it’s too loose or tight, you’ll need to adjust the barrel adjuster, typically located where the cable enters the rear derailleur or at the shifter on the handlebars.

To increase tension Turn the barrel adjuster counterclockwise. To decrease tension Turn it clockwise.

Step 3 Limit Screws Adjustment The back derailleur has two limit screws marked H (high) and L (low), which prevent the chain from falling off the cassette. Shift to the highest gear again and check the position of the derailleur.

- For the H screw adjustment If the derailleur doesn’t align directly under the smallest cog, adjust the H screw. Turning it clockwise will restrict the derailleur's movement to the right, while counterclockwise will allow it to move left. Next, shift to the lowest gear (largest cog) and check the L screw. If the chain is rubbing against the spokes, adjust the L screw clockwise.

Step 4 Fine-tune the Adjustments Once you've set the limit screws, it’s time for a test ride. Shift through all the gears and observe how the derailleur responds. If you notice any hesitation, skipping, or rubbing noises, you may need to adjust the cable tension further.

While riding, pay attention to how the bike behaves. If you still experience issues, return to the barrel adjuster and make small adjustments, then test again until the shifts feel smooth and reliable.

Step 5 Lubricate the Chain After adjusting the derailleur, make sure to lubricate your chain to ensure optimal performance. Clean the chain with a degreaser, then apply chain lubricant sparingly while turning the pedals backward, allowing the lubricant to penetrate the links.

Conclusion Adjusting the back derailleur on your mountain bike is a straightforward process that can significantly enhance your riding experience. By following these steps and regularly maintaining your bike, you can ensure smooth gear changes and prolong the life of your components. If you still have trouble after making these adjustments, it may be wise to consult a professional at your local bike shop for further assistance. Maintaining your bike not only improves performance but also enhances your overall riding experience, keeping you on the trails longer and more efficiently. Happy riding!