If you have a bike with more than one front chainring (the large sprockets attached to the pedals), you will need a front derailleur to shift the chain between them. A front derailleur is a device that moves the chain sideways by pushing it with a metal cage. It allows you to adjust your gear ratio for different terrain and speed.

How does a front derailleur work?

A front derailleur is attached to the seat tube of your bike frame, either with a clamp or a bracket. It has a cable that connects it to a shifter on your handlebar. This cable can either be a steel cable (mechanical), an electrical cable, or wireless (electronic). Moving the shifter pulls or releases the cable, which moves the derailleur cage inwards or outwards. In the case of electronic groupsets, a signal is passed from the shifters to the front derailleur wirelessly or through a small cable bespoke to each manufacturer (Shimano, SRAM, Campagnolo etc.)

The cage has two plates: an inner plate and an outer plate. The inner plate guides the chain onto the smaller chainring for easier pedalling, while the outer plate guides it onto the larger chainring for faster pedalling. The cage must be aligned properly with the chainrings to avoid rubbing or dropping the chain.

What are some types of front derailleurs?

Different types of front derailleurs depend on how they are mounted and how many speeds they support. Some common types are:

Braze-on: This type of derailleur has a small tab that bolts onto a braze-on mount on the seat tube. It is usually lighter and more adjustable than other types but requires a compatible frame.
Clamp-on: This type of derailleur has a band that wraps around the seat tube and clamps it in place. It can fit different diameters of seat tubes but may add some weight and bulk.
E-type: This type of derailleur has an extra bracket that attaches to the bottom bracket shell of your bike frame. It is often used for mountain bikes with suspension forks or frames lacking space for other derailleurs.
Direct mount: This type of derailleur has no clamp or bracket but bolts directly onto special mounts on some bike frames. It offers better clearance and stability than other types but requires a compatible frame.

Front derailleurs also vary in how many speeds they can handle. Most modern bikes have either 11-speed or 12-speed drivetrains, which means they have 11 or 12 sprockets at the rear wheel. The front derailleur must match this number to ensure smooth shifting.

How do I choose a front derailleur?

When choosing a front derailleur for your bike, you should consider the following:

Compatibility: Make sure your front derailleur matches your frame mount type (braze-on, clamp-on, etc.), your drivetrain speed (10-speed, 11-speed, etc.), your shifting (mechanical or electronic) and your chainring size (compact, standard, etc.). You should also check if your shifter is compatible with your derailleur brand (Shimano, SRAM, etc.). Some brands can mix and match. However, most use different cable pull ratios or electronic shifting protocols that may affect shifting performance.
Quality: Look for features such as durable materials (aluminium alloy), smooth bearings (ceramic), precise adjustment screws (micro-adjust), and low friction cables (coated). These can improve shifting accuracy and longevity.
Price: Front derailleurs range from budget-friendly options ($50-$200) to high-end, electrically shifted models ($300+). You can find good quality derailleurs at various prices depending on your needs and preferences.

Where can I buy a front derailleur?

You can buy front derailleurs online or at local bike shops. Online shopping offers more variety and convenience, but you may need some technical knowledge to install and adjust them yourself. You can find great deals on front derailleurs at BikeExchange. We’re Australia's leading marketplace for everything bike-related. You can browse through thousands of products from hundreds of retailers across Australia.