Cycling - Gear/Equipment

Cycling Gear: How to Replace or Realign the Derailleur Hanger

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A rear derailleur hanger is a replaceable part which is made out of an alloy and links the rear derailleur and the frame of a cycle together. In any situation where there is an impact caused to the derailleur, the hanger would take the impact on itself so as to protect the derailleur and the frame as much as possible.

If the gears of your cycle aren't working properly then it is mostly because of a bent hanger! This is because the standard derailleur is responsible for shifting gears. While the derailleur hanger is responsible for keeping the derailleur in place otherwise the changing of gears on your bicycle could get tricky. Understand the basic steps to replace a hanger and to realign it so that it is back in its perfect position.

How to Find the Right Derailleur Hanger

When you realize that your rear derailleur hanger broke, or needs replacement, you should start looking for a new one. Choosing the perfect derailleur hanger for your bike may require a bit of an investigation. The very first thing you need to remember is the fact that the derailleur hangers are different for different bikes and models.  

broken derailleur hanger
A broken derailleur hanger

Therefore, before you make a purchase, make sure that you have chosen the right one! Sometimes you will have the choice of choosing between two hangar types: the direct mount hanger and the standard drop-out. You can even find specialized derailleur hangers that suit your taste and necessity.

The direct mount hanger is a comparatively newer than the direct mount hanger and it is known for placing the derailleur approximately 25mm further back compared to the standard drop-out.

Derailleur hanger
Closeup of a derailleur hanger

Alignment Tools to Replace a Derailleur Hanger

There are two main tools which are needed to replace this:

  1. Hex Wrench
  2. Torx keys

The following are steps to change the Derailleur Hanger:

Step 1: Removing the Damaged Components

The very first step towards changing the derailleur hanger is to remove the parts that you do not need anymore. There will be a small piece of alloy attached to the rear derailleur. You will need to hold this torn piece of alloy with vise grips or pliers or anything that would hold it firmly.

Use a 5mm Allen Key to turn the bolt present in the center which screws into the alloy piece in an anti-clockwise direction until all the threads have been pulled away leaving the scrap alloy piece in your grip.

To replace broken derailleur hanger, the next step is to get rid of the destroyed rear derailleur hanger. If you remove the rear wheel and look carefully at the place where the derailleur came from, you will notice the portion where the rest of the alloy hanger is attached. It will be attached to the frame with two small fasteners. Once you remove the fasteners, you will be able to take the hanger out.

Step 2: Installing the New Replaceable Hanger

Now that you have gotten rid of the old hanger, you will be able to attach the new one. Use the 3mm Allen Key, unscrew the two fasteners and then insert the new one behind the frame. Once that is done, insert the two fasteners in place and tighten it until it feels snug. Make sure that you aren’t over tightening these as they are very delicate and might break.

installing the derailleur
A new derailleur hanger

Step 3: Installing the Rear Derailleur and Wheel

To begin, you should first start attaching rear derailleur to hanger. Hold the rear derailleur closer to the new hanger. You will notice a very small lip at the hanger’s bottom where the threads and the holes meet for the derailleur to screw into. The lip is there for the derailleur Limit Screw A which is visible at the back next to the threads where the derailleur screws in.

You will need to position the A Limit in such a way that the end of it is sitting right against the hanger’s lip. While fitting a rear derailleur, you need to make sure that everything is in position. Now, begin to screw in the rear derailleur to the hanger with the help of a 5mm Allen Key until it feels snug.

Unless and until the B limits of the derailleur have not been altered, the shift indexing has to be accurate. The rear derailleur would have to be reset if the shift indexing isn’t accurate.

How to Realign Your Derailleur Hanger Using the Proper Tool

Most people often wonder how to fix a bent derailleur hanger. The process isn’t as complicated as it seems to be. The derailleur hanger alignment tool to fix this aren't cheap but they can definitely make your job easier when it comes to replacing it.

Begin by unscrewing the bent derailleur hanger and allow it to dangle. Screw the tool in again. Align it in such a way that it dangles directly below the hanger. Adjust it so that the rim is touched by the end of the gauge.

Next, move the tool 9 o’clock and then 12 o’clock. Note if it is moving away from the rim or towards it. This would tell you as to how much the hanger is bent and in which direction.

Once you get to know about the bend, just apply pressure through the tool to realign the bent derailleur hanger into its original position. Keep checking regularly with the rim to ensure that it is as straight as you can get it to be. Finish off by removing the tool and then fitting everything back into place.

Realigning Your Rear Mech with an Allen Key

If you are out for a ride and unfortunately bend the hanger, this is one of the best ways to fix it! For this, you must have an L-shape Allen Key with yourself. Use the tool’s tail to realign it back to place.

Make sure that it is kept parallel to the sprockets and with the help of your hands, level the derailleur hanger back to its correct position.

hex wrench
Hex Wrench

Realigning Your Rear Mech with an Adjustable Spanner

This method is a bit complicated than the others but will prove to be beneficial especially if you find yourself in a difficult situation. Adjust the jaws in such a way that it clamps around the rear hanger and then put it back into place.

This job might be less accurate as in this technique, you are doing everything based on what you see. However, if done properly, it will help in getting the hangers back into its correct place. Once you are done with it, you would need to re-adjust the gears.

Torx Keys

Summing Up

Follow all of the steps mentioned properly and you will be able to fix the derailleur hanger yourself soon with all the expertise. You can find the necessary tools at any mechanic or bicycle store and even specialized derailleur hangers!

For some, this might be a tedious process when doing for the first time, but once you do it correctly, your confidence will double!

Whatever you do, do it carefully and with a lot of patience.

For more on gear read 10 Cycling Gear and Accessories You Should NOT Miss!

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