The Bike Cassette: All You Need To Know

Ever gone into a bike shop and felt like the people working there are speaking a different language?

Identifying and explaining your problem when something goes wrong with your bike can be pretty overwhelming; there’s a lot to get to grips with, and you can sometimes feel like you don’t have a clue how your bicycle actually works.

That’s why getting to know all the parts of your bike is a crucial task for any cycling fanatic – doing this can seriously improve your riding experience.

In this article, we’ll be explaining everything you need to know about the bike cassette, covering:

  • What Is A Bike Cassette?
  • What Do Bike Cassette Sizes Mean?
  • Road Bike Cassettes
  • Mountain Bike Cassettes
  • Gravel Bike Cassettes
  • Getting To Know Your Bike

Ready to lift your cycling knowledge to the next level?

Let’s get started!

The Bike Cassette Explained: Title Image

What Is A Bike Cassette?

Most modern bikes come with derailleur gears, which use a rear derailleur to move your chain up or down a set of sprockets attached to your rear wheel.

As a collective, the set of sprockets at the rear wheel is called the “cassette”.

This cluster of sprockets – or cassette – is a crucial part of your drivetrain that slides onto the freehub (the ratchet system that controls your bike’s drive when you pedal).

Cassettes come in a wide range of sizes to suit all disciplines. A cassette typically has anything from 5 to 12 sprockets, or “speeds”.

The bike cassette is a surprisingly complicated bit of machinery.

Firstly, it’s important to note that the sprockets in a cassette are designed to work together as a whole, rather than just being a collection of cogs. Each individual sprocket is positioned in relation to one another in order to make sure the chain shifts smoothly between cogs.

Individual teeth on the sprockets are shaped in different ways to further ensure smooth shifting between gears, and there are usually ramps built into the sides of the sprockets, too.

Different manufacturers have developed different ways of structuring their cassettes. Shimano, for example, uses a system called Hyperglide, which is engineered to provide smooth shifting.

Other cassette suppliers, such as SRAM and Campagnolo, have also honed their own specific cassette designs. And it’s also worth mentioning that as they’re built as a whole system, the sprockets in a cassette aren’t usually sold individually, and need to be replaced as a group.

Close-up shot of a bicycle cassette against a white background.

What Do Bicycle Cassette Sizes Mean?

The size of a bicycle cassette is crucial to its performance. Sizes also vary depending on whether you’re riding a road bike, mountain bike, gravel bike, or some other type of hybrid bicycle.

Usually, the size of a cassette is expressed by quoting its smallest and largest cogs. Common examples could be “11-32” or “10-52” – but what exactly do those numbers correspond to?

Essentially, the numbers indicate the smallest and the largest number of teeth in the cassette. For example, on an 11-28 bike cassette, the smallest sprocket will have 11 teeth on it, whereas the largest sprocket will have 28 teeth.

The small and large sprockets have different jobs. The small sprocket is what you’ll use when you’re seriously cranking speed, meaning that in flats and down hills, the fewer teeth you have, the more power you’ll have for generating speed.

On the large sprocket, meanwhile, the more teeth you have, the easier it’ll be for you to climb hills. Now, you might think that the ideal solution is to have a cassette that does it all, with a very small sprocket for speed and a very large sprocket for easy climbing.

But this isn’t always the best solution.

That’s because when you have a really wide range in your cassette, the transitions between each gear become a little bit more noticeable, and a little bit less smooth.

Your best bet is to really think about what kind of rider you are, and what your priorities are.

Do you ride a road bike or a gravel bike? Do you tend to cycle hilly routes or flatter roads? How fast do you usually cycle?

With those questions in mind, let’s take a look at the major differences between road bike, mountain bike, and gravel bike cassettes.

Close-up of a bike cassette on a white road bike.

Road Bike Cassettes

Road bike cassettes have grown in recent years in line with increases in cassette speeds.

A typical modern road bike cassette may be an 11-32t (teeth) cassette. While this used to be considered towards the larger end of the spectrum, it’s now the smallest cassette size available for some manufacturers.

Ultimately, different manufacturers take different approaches. Shimano’s latest R9200 is offered in 11-28, 11-30, and 11-34 options, while Campagnolo adds an 11-29 option for all of its 12-speed groupsets.

Meanwhile, SRAM has revamped its sizing, with road bike cassettes available in 10-26, 10-28, 10-30, 10-33, and 10-36.

The rise of 12-speed road bike groupsets means that cassettes can have a larger range and the jumps between each gear can be relatively small. Riders these days are also less likely to grind away in lower gears unnecessarily, which thankfully reduces the risk of knee pain.

Close-up of a bike cassette on a black mountain bike.

Mountain Bike Cassettes

Mountain bike cassette sizes have also increased in recent years, largely due to the arrival of 1x drivetrains – with no small inner ring for climbing in a 1x setup, cassettes must now offer a wider range in order to equip riders with a suitable climbing gear.

For mountain bikes, a wider range of gears is important to help riders cope with the varying terrain that they may face.

For example, short, steep technical climbs will tend to require very low gearing (largest sprocket), while longer descents that will usually be cycled faster will make use of the smallest sprocket.

Typically, most mountain bikes will use anything between a 9-speed and 12-speed cassette, although more budget models can sometimes use as narrow as a 7-speed cassette.

A classic gear spread for a mountain bike cassette would be 11-34 or something similar.

Mountain bike cassettes also typically differ from road bike cassettes in having greater gaps in gearing between each sprocket.

Disconnected sprockets from a bike cassette.

Gravel Bike Cassettes

Gravel bikes take features from both road bikes and mountain bikes in order to reach an optimum balance between the two depending on the aims of the manufacturer.

Back in the day, the cassette on a gravel bike would be either a road bike or mountain bike cassette, but these days, there are also gravel-specific options available on the market.

SRAM’s eTap AXS XPLR groupsets are designed especially for gravel riding, while Campagnolo is the only mainstream groupset manufacturer to have a 13-speed groupset for gravel bikes.

The varying terrain that gravel bikers (or general hybrid bike users) will often end up riding on makes having the right bike cassette size all the more important.

But ultimately, the cassette is just one aspect of your bicycle that you’ll need to get to know in order to get the best out of your riding experience.

Found this bike cassette guide helpful? Find more from the BikeTips experts below!

Fred Garratt-Stanley

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