How To Install A Rear Derailleur On A Mountain Bike? (Step by Step)

Mountain biking is a great way to get outdoors and enjoy some exercise. But to get the most out of your mountain biking experience, it’s important to have a bike that is in good working order. 

This includes making sure your derailleurs are properly adjusted. The rear derailleur is responsible for shifting the chain between the different gears on the rear cassette. If the rear derailleur is not properly installed or adjusted, it can cause problems when shifting gears.

In this article, we will discuss how to install a rear derailleur on a mountain bike. We’ll also go over some tips for adjusting the derailleur to work properly.

Type Of Derailleur

There are two types of derailleurs: front and rear. The front derailleur moves the chain between the two or three chainrings of the crankset, while the rear derailleur moves between the sprockets of the cassette (sprocket cluster).

The front derailleur is mounted on the frame, just behind the bottom bracket. The rear derailleur is mounted on the frame, below the seat stay.

Can You Put Any Derailleur On A Bike?

No, you cannot put any derailleurs on a bike. It is often assumed that any derailleur can be used on any bike. However, this is not always the case. There are a few things to consider when choosing a derailleur for your bike.

4 things to consider when choosing a derailleur for your bike:

  1. Size of the derailleur
  2. Type of shifter you are using
  3. The capacity of the derailleur
  4. Compatibility of the derailleur with your bike

1- Size of the derailleur

There are two main sizes of derailleurs, standard and compact. Standard derailleurs are typically used on mountain bikes and have a larger cage. This allows them to accommodate a wider range of gears. 

Compact derailleurs are typically used on road bikes and have a smaller cage. This makes them more aerodynamic but limits the number of gears they can accommodate.

2- Type of shifter you are using

There are two main types of shifters, trigger shifters, and grip shifters. Trigger shifters are located on the handlebars and are operated by your thumb. Grip shifters are located on the end of the handlebars and are operated by your fingers. Each type of shifter is compatible with certain types of derailleurs.

Trigger shifters are typically used with standard derailleurs. Grip shifters are typically used with compact derailleurs.

3- Capacity of the derailleur

The capacity is the maximum number of gears the derailleur can accommodate. The capacity is determined by the size of the cage and the type of shifter.

Standard derailleurs typically have a capacity of 27 gears. Compact derailleurs typically have a capacity of 21 gears.

4- Compatibility of the derailleur with your bike

Some bikes have special mounting requirements for certain types of derailleurs.

Is It Easy To Replace A Rear Derailleur On A Bike?

No, it’s not difficult to replace the rear derailleur on a bike. The hardest part is usually getting the old one off, but with a little patience and the right tools, it can be done relatively easily.

Most rear derailleurs come with instructions on how to install them. Follow these instructions carefully. If you are not sure about something, ask a friend or take your bike to a bike shop for help.

How To Install A Rear Derailleur On A Mountain Bike? (Step by Step)

You might be wondering how to go about installing a rear derailleur on your mountain bike. It’s not as difficult as it might seem at first, and with a little patience and attention to detail, you’ll have it done in no time. 

Here are 5 basic steps to install a rear derailleur on your mountain bike:

  • Step 1: Remove the chain from the bike
  • Step 2: Remove the old rear derailleur from the bike
  • Step 3: Install the new derailleur
  • Step 4: Adjust the limit screws on the derailleur
  • Step 5: Adjust the tension on the derailleur spring
  • Step 6: Adjust the barrel adjuster on the derailleur
  • Step 7: Adjust the derailleur hanger

Step 1: Remove the chain from the bike

This can be done by shifting the derailleur into the smallest cog and then removing the chain from the cog. 

Step 2: Remove the old rear derailleur from the bike

To do this, remove the derailleur hanger bolt using a derailleur hanger tool. There are usually two bolts holding it in place, one at the top and one at the bottom.

Once the derailleur is off, take a look at how it is attached to the frame. There are usually two different types of attachment, either a hanger or a direct mount. If your bike has a hanger, then you will need to remove the hanger before you can remove the derailleur.

If your bike has a direct mount, then the derailleur will be attached directly to the frame. In this case, you will need to remove the bolts that are holding it in place. Once the derailleur is off, take a look at the new one that you will be installing.

Step 3: Install the new derailleur

Take the new derailleur and attach it to the derailleur hanger. Make sure that the derailleur is positioned so that the pulleys line up with the cogs on the rear cassette. Insert the derailleur hanger bolt and tighten it securely.

Step 4: Adjust the limit screws on the derailleur

The high-limit screw should be adjusted so that the derailleur can move the chain onto the largest cog on the rear cassette. The low-limit screw should be adjusted so that the derailleur can move the chain onto the smallest cog on the rear cassette.

These screws control how far the derailleur can move. If they are not set correctly, the chain can fall off of the cog.

To adjust the limit screws, turn them clockwise to move the derailleur further away from the cog. Turn them counterclockwise to move the derailleur closer to the cog.

Step 5: Adjust the tension on the derailleur spring

Once the limit screws are set, you will need to adjust the tension on the derailleur spring. This spring controls how tight the chain is held on the cog. If the spring is too loose, the chain can fall off.

If the spring is too tight, the chain will not be able to shift smoothly. To adjust the tension, turn the tension screw clockwise to increase the tension. Turn the tension screw counter-clockwise to decrease the tension.

Step 6: Adjust the barrel adjuster on the derailleur

Next, adjust the barrel adjuster on the derailleur so that the chain is running smoothly between the cogs on the rear cassette.

Step 7: Adjust the derailleur hanger

Finally, you will need to adjust the derailleur hanger. The hanger is what the derailleur is attached to on the frame. If it is not set correctly, the chain can fall off.

To adjust the hanger, turn the hanger bolt clockwise to move the hanger up. Turn the hanger bolt counter-clockwise to move the hanger down.

After the hanger is adjusted, you will need to check the chain alignment. The chain should be straight when it is on the smallest cog. If it is not, the chain can fall off.

To check the chain alignment, shift the derailleur into the smallest cog. Then, look at the chain. It should be straight. If it is not, you will need to adjust the hanger.

Once the chain is aligned, you will need to test the shifting. Put the chain on the bike and shift through all of the gears. The chain should shift smoothly through all of the gears.

If the chain does not shift smoothly, you will need to adjust the limit screws or the tension screw.

With these basic steps, you should now be able to install a rear derailleur on your mountain bike. Just remember to take your time, be patient, and consult your manual or a bike shop if you’re unsure of anything.

What Can Cause A Rear Derailleur To Break?

A rear derailleur can break for several reasons, the most common being an impact on an object such as a rock or pothole. Other causes of breakage include excessive force being applied to the derailleur, as can happen when shifting gears too hard, or a build-up of dirt and grime.

How To Install A Rear Derailleur On A Road Bike?

Here are 4 steps to install a rear derailleur on a road bike:

  • Step 1: Remove the old rear derailleur from the bike
  • Step 2: Install the new rear derailleur
  • Step 3: Route the chain through the derailleur
  • Step 4: Adjust the derailleur

Step 1: Remove the old rear derailleur from the bike

To do this, start by removing the chain from the bike. Once the chain is removed, you will be able to see the derailleur. There are two bolts that hold the derailleur in place. Use a wrench to remove these bolts.

Step 2: Install the new rear derailleur

To do this, first, attach the derailleur to the frame. There are typically two attachment points one at the top and one at the bottom. Once the derailleur is in place, you can then bolt it into place.

Step 3: Route the chain through the derailleur

Start by threading the chain through the bottom pulley. Then, thread it through the top pulley. You may need to use a screwdriver or another tool to help guide the chain through the pulleys.

Step 4: Adjust the derailleur

This is done by turning the screws that are located on the derailleur. These screws are typically labeled L and H. The L screw adjusts the low limit, while the H screw adjusts the high limit. You will need to experiment with these screws until the derailleur is properly adjusted.

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Author
Allen
Hi, I'm the initiator and writer of this blog. Bikes were and will be my first love, and my favorite hobby, that's why I decided to start this blog and write about my discoveries and techniques to improve my bikes or repair them.

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