Bicycle Clutches (What They Are and How They Work)

Flying down the road during a group ride, I hit a pothole. Hard. And then it happened – the dreaded chain slap. The chain bounced around, jammed up, and after a bit of maneuvering, popped back on. But not before I fell to the back of my group and had to sprint to catch back up with the pain train. 

If you’re not sure what I’m talking about, that’s great! But, you hopefully haven’t experienced it. Chain slap is one of the annoying and frustrating parts of bike riding. It happens when you hit a bump or pothole and your rear derailleur bounces, causing the bike chain to lose tension. When the chain loses tension, it can flop around and make noise, make it hard to pedal, pop off, or even get stuck in your spokes

This type of chain slap doesn’t happen too often on road bikes unless you’re hitting the cobblestones, but it does happen more often on gravel and mountain bikes. And for this reason, the bicycle clutch was created. 

Do All Bicycles Have Clutches?

Not all bicycles have clutches, even though they are increasing in popularity. For example, a typical road bike doesn’t usually need a clutch since it is designed to be used on smooth roads where the chain won’t bounce up and down. Instead, the rear derailleur and jockey wheels on a road bike are what keep the chain taught enough to ride. 

Track bikes, or fixed gear bikes, don’t have a clutch, either. Instead, you have a little space in the wheel mount to slide the wheel forwards and back to adjust the tension on the chain. Since you don’t have to shift, you don’t need a clutch or other mechanism to adjust the chain tension while you are riding. You can set it and forget it. 

You can learn a bit more about when you might need a clutch, in this video:

Now let’s talk a little more about the other types of bikes that do have clutches. 

Types of Bikes That Have Clutches

Certain types of riding call for a little extra chain support, especially when it involves rough, rocky, or gravelly terrain. Bikes that go off-road are more likely to use a clutch. 

Mountain Bikes 

Mountain bikes are designed for the roughest terrain, such as rock gardens, singletrack, and narrow dirt trails. Most mountain bikes are tough and rugged, with wide bars and big gnarly tires. Mountain bikes are the most common type of bikes to have clutches since they have to handle the bumpiest, bounciest terrain, which creates loads of chain slap. 

Gravel Bikes

Many gravel bikes have clutches, but not all. Gravel bikes don’t usually ride on terrain as challenging as mountain bikes, but they do go off-roading and on trails where you might encounter tree roots, holes, and bumps. Some gravel bikes, especially those with 1x gearing, will have clutches to help keep that chain under control. However, 2x setups are less likely to have clutch derailleurs. 

Cyclocross Bikes 

CX bikes are increasingly becoming 1x setups. These bikes are designed to be raced over a variety of terrain, from dirt to grass, to sand, steep hills, and of course, loads of obstacles. Since this can wreak havoc on your chain’s stability, CX bikes are starting to use clutch derailleurs more frequently, especially on those bikes that only have one front chainring. 

Road bikes 

Road bikes are the least likely to feature a clutch, but it is an option. Some pro cyclists are opting to add clutch derailleurs to their bikes for racing over cobbles, and you might want to consider that option as well. 

A bicycle clutch can save your ride, prevent an accident, and prevent damage to the chainstay of your bike. But what exactly is a bicycle clutch? 

What Are Bicycle Clutches?

If you’ve ever driven a stick shift, you’ll know that a car has a clutch for shifting gears. But a bicycle clutch is slightly different since it doesn’t have to deal with the same level of torque and stress as a car clutch does. 

Simply put, a bicycle clutch is a component of the rear derailleur that keeps tension on the chain. When you shift your bike, the derailleurs in the front and the back will move the chain to the desired chainring or cassette. Without your bike’s derailleurs, you wouldn’t be able to change gears. 

So a bicycle clutch is technically a part of the rear derailleur that makes it work better. Now let’s take a look at exactly how a bicycle clutch works. 

How Do Bicycle Clutches Work?

A bicycle clutch is a part of the bike’s drivetrain. The front derailleur is what changes gears on the front chainring, while the rear derailleur is what works the shifting mechanism to change gears on the cassette. 

You can get a look inside the clutch mechanism to see how it works in the video below:

The Rear Derailleur

The rear derailleur is the part of the bike that moves the chain through the cassette on the back wheel into the desired gear. You’ll push a button or lever on your handlebars to move that chain into an easier gear via the rear derailleur when you are going uphill. If you go downhill, you’ll push the other button or lever to put the bike into a harder gear to keep your cadence consistent and comfortable. 

Without the rear derailleur, you just wouldn’t be able to shift the chain into the different gears on the rear cassette. The rear derailleur has just enough tension to move the chain where it needs to go without making it stiff or hard to shift. 

Maintaining Chain Tension

When you are riding your bike and hit a bump, that rear derailleur arm can bounce up and down. When the arm bounces around, the tension on the chain loosens. 

When you lose that perfect chain tension, the chain can slap the chainstay and damage the frame. It might also bounce off, meaning you drop your chain. Finally, the chain could become loose enough to get tangled in the spokes, causing an accident and damaging the wheel and the bike. 

This type of scenario is where the bicycle clutch is helpful. The clutch is a part of the rear derailleur on some bikes to keep the derailleur arm from bouncing up and down too much, helping keep that derailleur in place so that you don’t lose tension on the chain. 

Keeping the correct tension on the chain is important on bikes designed for rough roads and uneven terrain, such as mountain biking, gravel riding, and of course, cyclocross. These types of cycling disciplines are far more likely to experience chain slap and drop. 

Ollie at Global Cycling Network gives a great example of a rear derailleur in action in the video below:

Thankfully, you don’t really have to think about how to use the bike clutch when you’re riding. Once you have one, it does the work all by itself. 

Using the Bike Clutch

Using a bike with a clutch isn’t like driving a car with a manual transmission. You don’t have to push a pedal or pull a lever to engage it. Although it does assist the drivetrain, you don’t have to engage it every time you shift. 

If your bike has a rear derailleur clutch, you always want to ride with it in the on position, or it won’t do its job. Usually, a clutch will feature a toggle with a lock vs. unlock icon to show whether the clutch is engaged or disengaged, but double-check your bike’s user manual to make sure. You only need to put the clutch in the off position if you should need to remove the rear wheel. Then when you replace the wheel, make sure to reengage the clutch. 

If you don’t have a bike clutch, it is possible to upgrade your rear derailleur to one with a clutch. However, you can’t always mix and match any rear derailleur with any drivetrain, so you’ll need to make sure all components are compatible before upgrading your rear derailleur.

In the market for a new rear derailleur? Check out some of the best, most popular clutch derailleurs listed below: 

Top Bicycle Clutches (5 Examples)

Now if you’re interested in getting a clutch for your bike, here are a few examples that you could consider:

  • Shimano Ultegra RD-RX800/RD-RX805 rear derailleur. This clutch derailleur is made to reduce noise and prevent dropped chains. It is especially suitable for gravel, cyclocross, and adventure bikes. However, it will add weight to your bike. 
  • Shimano GRX 812. Shimano’s GRX line was explicitly created with gravel riding in mind. This clutch mech is designed for quiet, precise, and secure shifting on gravel terrain. 
  • MicroSHIFT XCDThis clutch derailleur claims to be compatible with Shimao drivetrains and offers precise, quiet shifting at a budget price. 
  • Sunrace MZ900This clutch derailleur boasts 12 speed and Shimano compatibility, but the clutch only holds the cage and not the entire derailleur. In addition, it uses brushes rather than bearings, which creates extra friction but is very lightweight. 
  • SRAM GX Eagle. The SRAM GX Eagle Derailleur is meant to be used with their 1x drivetrains. It offers precise shifting and eliminates ghost shifting, which is when a derailleur shifts gears on its own without the rider hitting the shift lever: a very annoying occurrence when you’re not expecting it!

Rob Marlowe

With years of experience as a dedicated mountain biker and an unwavering passion for research, I have cultivated a deep expertise in all facets of cycling—from the intricacies of bike mechanics and gear optimization to the subtleties of riding techniques. My journey has been one of continuous learning, driven by countless hours delving into the science and art of biking. It's this wealth of knowledge and practical know-how that I aim to impart, offering a trusted resource for novices to gain their footing and for seasoned riders to refine their skills and push their limits.

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