How to Identify a Derailleur Hanger: 5 Reliable Methods

If your rear derailleur was damaged, your bike fell over, or you simply need a replacement derailleur hanger, the first challenge is identifying the correct one.

Unfortunately, derailleur hangers are not universal. There are thousands of different designs, and even bikes from the same manufacturer may use different hangers depending on the model year, frame version, axle type, or groupset.

The good news? With a few simple checks, you can usually identify the correct hanger quickly and avoid ordering the wrong part.

At Elanus Parts we have helped cyclists identify thousands of derailleur hangers and maintain one of Europe's largest derailleur hanger compatibility databases. Browse over 2,000 replacement derailleur hangers.

What Is a Derailleur Hanger?

A derailleur hanger is a small replaceable metal part that connects the rear derailleur to the bike frame. 

It is intentionally designed to be weaker than the frame. If the bike falls or the derailleur takes an impact, the hanger bends or breaks first, helping protect your frame from damage. More...

Common signs of a damaged hanger:

• Gears no longer shift correctly.
• The derailleur appears tilted toward the wheel.
• Chain skips unexpectedly.
• Hanger is visibly bent or cracked.
• Rear derailleur has broken off the frame.

Method 1: Identify by Bike Brand and Model

The easiest way is to know:

• Bike manufacturer
• Model name
• Model year

For example:

• Trek Fuel EX 2022
• Specialized Stumpjumper 2021
• Giant Talon 2020
• Canyon Spectral 2023

Many modern bike manufacturers change hanger designs over time, so the model year is often important.

Where to find the model information?

• Original purchase documents
• Frame decals
• Manufacturer website
• Bike serial number lookup, if available

If you know the exact bike model, identification becomes much easier.

Method 2: Compare the Original Hanger

If the original hanger is still available, remove it from the frame and inspect it.

Look at:

• Overall shape
• Bolt locations
• Axle hole design
• Thickness
• Alignment tabs
• Threaded mounting points

Method 3: Take Clear Photos

Photos are usually the fastest and most reliable identification method.

Best photos to provide:

1. Both sides of the hanger

Place the hanger on a flat surface and photograph:

• Front side
• Back side

2. Frame dropout area

Take photos showing where the hanger attaches to the frame.

3. Entire bike, optional

A full bike photo can sometimes help confirm the model.

Avoid:

• Blurry images
• Photos with the derailleur still attached
• Pictures taken from only one angle
• Dark or low-resolution images

Method 4: Check the Part Number

Some hangers have part numbers stamped or engraved on them.

Examples:

• GH-123
• DROPOUT-456
• Pilo D789

If a part number is visible, identification becomes much easier.

However, not all hangers include markings, and some numbers may refer only to manufacturer production batches.

Method 5: Check the Rear Axle Type

Modern bikes commonly use:

Quick Release (QR)

• Traditional skewer
• Usually 5 mm rod with lever

Thru Axle

Common sizes include:

• 12 × 142 mm
• 12 × 148 mm Boost
• 12 × 157 mm Super Boost

Some hangers are specific to the axle type, so this information can be critical.

Why Identifying by Eye Is Difficult

Many cyclists are surprised to learn that there are more than 2,000 derailleur hanger designs currently in use.

Even bikes from the same manufacturer may use:

• Different hangers for carbon and aluminum frames
• Different hangers for various frame generations
• Different hangers depending on rear axle standards

Because of this, searching only by brand is rarely enough.

What If the Original Hanger Is Missing?

Don't worry. In most cases, identification is still possible using:

• Photos of the frame dropout area
• Bike brand and model
• Bike model year
• Rear axle type

Experienced bike parts specialists can often identify the correct hanger from frame photos alone.

Tips Before Ordering

Before purchasing a replacement hanger:

• Verify bike model and year
• Compare photos carefully
• Check axle compatibility
• Inspect for frame damage
• Confirm the hanger shape from both sides

Taking a few extra minutes before ordering can save days of waiting for the wrong part to arrive.

Examples of Different Derailleur Hanger Designs

These derailleur hangers may look similar at first glance but are completely incompatible.

Need Help Identifying Your Derailleur Hanger?

If you're unsure which hanger fits your bike, send:

• Photos of the hanger from both sides
• Photos of the frame dropout
• Bike brand and model
• Approximate model year

The more information you provide, the easier it is to find the correct replacement and get your bike shifting perfectly again.

Need help identifying your derailleur hanger? Send us photos here.

Information Needed to Identify a Derailleur Hanger

• Bike brand
• Bike model
• Model year
• Rear axle type
• Photos of both hanger sides
• Photos of the frame dropout

Common Mistakes When Identifying a Derailleur Hanger

• Taking photos with the hanger still mounted on the bike.
• Photographing only one side of the hanger.
• Relying only on the bike model name.
• Ignoring axle type differences.
• Comparing only the outer shape instead of mounting details.

Can You Identify a Derailleur Hanger from a Photo?

Yes. In most cases a derailleur hanger can be identified from clear photos of both sides and the frame dropout area. This is the method used by most professional bicycle parts specialists and is often enough to identify the correct replacement without knowing the exact bike model.

Frequently Asked Questions About Derailleur Hangers

How do I identify the correct derailleur hanger for my bike?

To identify the correct derailleur hanger, remove the hanger from the frame and compare its shape, bolt holes, axle type and mounting side with replacement options. Bike brand, model and year can help, but clear photos of the original hanger from both sides are usually the most important.

Not sure whether your bike uses a traditional hanger, SRAM UDH or a Full Mount system? Read our derailleur hanger compatibility guide .

Why do I need to remove the derailleur hanger to identify it?

Many derailleur hangers look similar when mounted on the bike, but the inner shape, bolt position and contact surface are hidden by the frame. Removing the hanger makes it possible to compare both sides and identify the correct replacement more accurately.

Can I identify a derailleur hanger by bike brand and model only?

Sometimes, but not always. The same bike brand or model can use different derailleur hangers depending on the year, frame version, axle type or production batch. Photos of the original hanger help avoid ordering the wrong part.

What photos are needed to identify a derailleur hanger?

The best photos show the removed derailleur hanger from both sides, the frame dropout area where it mounts, bolt holes, axle interface and any broken pieces placed together. Clear close-up photos on a plain background make identification easier.

Are derailleur hangers universal?

No, most derailleur hangers are not universal. They are usually specific to the frame design, axle type and mounting shape. Even small differences in bolt position or thickness can make a hanger incompatible.

What is the difference between QR and thru axle derailleur hangers?

QR derailleur hangers are designed for quick-release axles, while thru axle hangers are made for modern thru axle frames. The mounting shape, axle hole and thread interface can differ, so it is important to match the hanger to the correct axle system.

Can a bent derailleur hanger be straightened?

A slightly bent derailleur hanger can sometimes be aligned using a proper hanger alignment tool. However, if the hanger is cracked, badly bent or has already been straightened multiple times, replacement is usually the safer and more reliable solution.

What should I do if my derailleur hanger is broken into pieces?

Place all broken pieces together and take clear photos from both sides. Also photograph the frame dropout area. Even broken hangers can often be identified if the bolt holes, axle area and overall shape remain visible.

Need Help Identifying Your Derailleur Hanger?

If you are unsure which derailleur hanger fits your bike, send us clear photos of the hanger from both sides, along with your bike brand and model. Our team will help identify the correct replacement.

About Elanus Parts: Elanus Parts is a European bicycle parts specialist offering derailleur hangers, drivetrain components, chainrings, wheel accessories and e-bike parts. We help cyclists identify compatible replacement parts for thousands of bicycle models from leading manufacturers.