A derailleur is a variable-ratio bicycle gearing system consisting of a chain, multiple sprockets of different sizes, and a mechanism to move the chain from one sprocket to another.

What does a derailleur do on a bike?

The rear derailleur is the mechanism that shifts the chain at the rear sprockets. There are many different models but they all share the same basic design and functionality. Derailleurs are secured to the bike with a mounting bolt to the frame's derailleur hanger.

Does every bike have a derailleur?

Most modern bikes are equipped with a derailleur gearing system - stay with me, we'll get to the terminology - where the chain runs between many different cogs.

Is a derailleur necessary?

Clutch derailleurs are good for off-road conditions, such as mountain bikers typically encounter, but are not necessary for road cycling. In fact, they can cost efficiency when riding, so they are not suitable for road cycling as the benefits are outweighed by the downsides.

Can you use bike without derailleur?

Technically, a mountain bike can work without a derailleur. If your derailleur stops working, you can rig it to keep the bike working. However, you also have the option to ditch it completely and make it a single speed, if you wish.

How a Rear Derailleur Works

How much does it cost to fix a derailleur?

If you take your MTB into a local bike shop the average price to replace a rear derailleur is going to be $110. If you DIY replacing a derailleur will cost about $50 (plus your time) This price will depend a lot on the actual derailleur needed. Usually a bike shop will also take care of other problems.

What is front derailleur?

The front derailleur is the mechanism that shifts the chain on bike with more than one front chainring. There are many different makes and models, but they all share the same basic design and functionality. Front derailleurs are attached to the bike with either a clamp or bracket.

Why do derailleurs have a clutch?

Clutch rear derailleurs are increasingly common on mountain bike drivetrains. The 'clutch' feature ensures tension is retained in the derailleur throughout its movement. ... A clutch mechanism helps the chain to stay much more taught, and therefore increases chain security.

Will any derailleur fit my bike?

A derailleur for your mountain bike should match the specifications on the original derailleur. That is, while it doesn't need to be the same model of derailleur, it does need to be the same brand, in almost every case. It also needs to match the number of gears, or have more intended.

Do derailleurs wear out?

Derailleurs will last almost indefinitely. The jockey wheels will wear out in time (tens of thousands of km) but the rest of the mechanism shouldn't see significant wear.

Do derailleurs have speeds?

The spacing between 9 speed and 10 speed is controlled at the shift lever. A 10 speed rear dérailleur will work with a 9 or 10 speed cassette and shifter. A 9 speed rear dérailleur is not compatible with 10 speed. The width of the chain and the cogs is the biggest issue.

Which Shimano derailleurs have a clutch?

Clutch derailleurs explained

Almost all modern mountain bike derailleurs (and Shimano's GRX gravel groupsets, Ultegra RX rear mech, SRAM's single-ring road groupsets and eTap AXS 12-speed road rear mechs) include a clutch mechanism.

Should Shimano clutch be on or off?

Installation is simple, the only added complication being that you must switch the clutch mechanism to the 'off” position before tuning your gears. With the clutch off, the lower arm is free to move unrestricted, making it easier to set your cable tension etc. With gear tuning done, flip the lever back to 'on'.

Are all Shimano front derailleurs compatible?

Shimano road and MTB FDs have different cable pull ratio – that is the amount of FD movement for each mm of cable movement. ... Having said all this and in spite of officially different cable pull, all the FDs almost always work OK with all the shifters, regardless whether it is road, or MTB.

Is it hard to install a derailleur?

It's relatively easy, and if you haven't done it before, you'll learn the procedure of tuning a rear derailleur <i>from scratch</i>, which can be invaluable out on the trail. Are you planning on installing a new cable? It's not required, but this would be the time to do it. If so, you'll need cable cutters.