A guide to bike groupsets

The groupset is the collection of bike parts that handle your bike’s gearing and braking, working together to transfer power from your legs to the wheels to help you move, as well as keep you in control when it’s time to slow down.

Different riding styles, such as road and mountain biking, place different demands on a groupset, which means they require different setups. The price of a groupset ranges widely depending on performance, weight, and materials. The more expensive the groupset, the more enhanced features it will have and the better your gears will shift. For road bike users, a lighter groupset also has benefits for the bike’s speed.

Below, we’ve listed all of the parts that make up a groupset, so you can get familiar with them before making a purchase.

Chainset

The chainset, sometimes referred to as the “crankset” in the bike world, features two crank arms alongside up to three chainrings.

The number of chainrings depends on the type of bike and what it’s used for. For example, single chainrings are often found on higher-end mountain bikes, while two or three chainrings are more common on road bikes and commuters. This is because the gear ratios vary between different cycling disciplines.

The three main drivetrain manufacturers are Shimano, SRAM, and Campagnolo.

Bottom Bracket

The bottom bracket is the part that connects the chainset to the bike itself. This small but important component sits inside the bike’s frame and allows the chainset to spin freely using bearings.

Some bottom brackets include an axle that the chainset connects to directly, while others use bearings and a shell that the chainset axle slots into. Bottom brackets can be either threaded or press-fit, which push straight into the frame.

Brakes

One of the most important parts of a groupset is the brakes.

Most mountain bikes use disc brakes, which work by a brake calliper squeezing a metal disc (called a rotor) attached to the centre of the wheel. Many road bikes also use disc brakes, but some still use rim brakes (also known as calliper brakes). Rim brakes work by squeezing the sides of the wheel’s rim using a cable, which slows the bike down.

Brake Levers

Brake levers are the small levers on your handlebars that activate the brakes when pressure is applied.

On road bikes, brake levers also double as gear shifters, allowing riders to change gear and brake without moving their hands. They use multiple movements on one lever to perform both functions. Mountain bikes use separate trigger shifters: the left shifter controls the front derailleur, and the right shifter controls the rear.

Electronic gear shifting can also be found on top-spec bikes. This system uses small electric motors instead of metal cables to change gears and is powered by a battery. Shifting only requires a light button press and can even be done wirelessly.

Derailleurs

Also known as “mechs,” derailleurs work alongside the shifters to change gears. Most bikes have two derailleurs: one controlling the front chainrings and one controlling the rear cassette.

Front derailleurs are becoming far less common on mountain bikes due to advancements in rear cassette technology, which allows riders to achieve a wide gear range without the need for a front derailleur.

Chain

The chain is what makes the bike move, so it’s important to keep it well lubricated and maintained to ensure smooth performance.

The chain connects to the cassette and moves through the derailleurs to propel the bike forward. Bike chains are specific to the speed of the drivetrain, meaning a 12-speed cassette requires a 12-speed chain to ensure compatibility.

Cassette

The cassette is the set of gears on the rear wheel. Each gear is a different size, which changes how easy or hard it is to pedal. Most bikes have between 6 and 12 gears on the cassette.

The rear derailleur moves the chain across the cassette when you use the shifters. Larger gears make pedalling easier, while smaller gears make pedalling harder.

Shop Cassettes

Now you know which parts make up a groupset, check out our range of bike parts online or head to your local Halfords store where one of our friendly experts will be happy to advise you further.

Shop Bike Parts

If you need help changing any of your bike parts, we offer plenty of bike services to help keep life on two wheels as smooth as possible. Check our bike maintenance and service offers that include cassette and shifter fitting, cable replacement, drivetrain cleaning and plenty more.