Rear Derailleurs for Bikes

Rear Derailleurs for Road, MTB and Gravel Bikes

The rear derailleur is an essential part of a bike’s drivetrain. It moves the chain between the sprockets on the cassette, allowing riders to select the right gear for the terrain and their pedalling cadence. A correctly adjusted rear derailleur that is compatible with the other drivetrain components helps ensure smooth, accurate and reliable shifting.

The range includes mechanical and electronic rear derailleurs for road bikes, mountain bikes and gravel bikes from leading component manufacturers.

How to Choose the Right Rear Derailleur

Before buying a rear derailleur, check that it is compatible with your existing drivetrain.

Number of Speeds, Cassette and Cage Length

Rear derailleurs are designed for specific drivetrain systems, with different numbers of speeds and gear ranges. Checking the number of sprockets alone is not enough: shifter compatibility, maximum sprocket size, total capacity and mounting type must also be considered.

Cage length, commonly identified as SS, GS or SGS on Shimano models, affects how much chain slack the derailleur can manage across different gear combinations. The exact specifications always depend on the model.

Mechanical or Electronic Rear Derailleur?

Mechanical rear derailleurs are generally cable-operated. They are available for a wide range of setups and are a versatile choice for both performance and everyday riding.

Electronic rear derailleurs, such as Shimano Di2 and SRAM AXS models, use electronic actuation for precise shifting. Before choosing one, check compatibility with the shifters, power supply and the rest of the groupset.

Shimano, SRAM and Campagnolo Rear Derailleurs

The range features rear derailleurs from well-known cycling component brands:

• Shimano: road, MTB and gravel options, including the 105, Ultegra, Dura-Ace, Deore, XT, XTR and GRX families.
• SRAM: road and off-road derailleurs, including Eagle, Rival, Force and RED models, as well as AXS electronic systems.
• Campagnolo: road drivetrain components, including options from the Super Record range.

Maintenance and Compatible Drivetrain Parts

For accurate shifting, regularly check drivetrain wear, pulley cleanliness and derailleur hanger alignment.

See also bike chains, cassettes, derailleur pulley wheels and front derailleurs.

Frequently Asked Questions About Rear Derailleurs

Is a rear derailleur the same as a rear gear changer?

Yes. Both terms refer to the component that moves the chain across the rear cassette. Rear derailleur is the standard term in English cycling terminology, distinguishing it from the front derailleur, which shifts the chain between chainrings.

Can I fit a 12-speed rear derailleur to an 11-speed bike?

Not automatically. Compatibility must be checked across the entire drivetrain, including the shifters, cassette and the manufacturer’s system requirements.

When should a rear derailleur be replaced?

Replace it if it has structural damage, excessive play or persistent shifting problems that cannot be fixed through adjustment and maintenance. First check the derailleur hanger, pulley wheels and the other drivetrain components.