Components

Cassettes buying guide

Category: Components

Cassettes buying guide


Introduction to cassettes


Your cassette is an integral part of your bike’s drivetrain. Found on the drive side of your rear hub, it consists of a number of circular metal discs with teeth around the edge, ranging from small to large – these are called ‘sprockets’.

When shopping for a new cassette you will notice that they vary in specification, from number of sprockets to number of teeth on each sprocket.

Your cassette will typically have 8, 9, 10 or 11 sprockets depending on the amount of gears in your transmission (9, 10 or 11 for road bikes). For example, a drivetrain with a 9-sprocket cassette and three front chainrings offers 27 gears in total (3×9), while two chainrings up front and a 10-speed cassette will deliver 20 gear options (2×10).

Sprockets vary in size according to the number of teeth they have. A cassette may therefore be sized as 11-32t. The first number refers to the number of teeth on the smallest sprocket (the highest gear, for fast pedalling at speed) and the second number to the biggest sprocket (the lowest gear, for climbing hills). The closer the two figures are together, the less pronounced the difference between gears (e.g. an 11-21t cassette is referred to as having a ‘narrow’ gear range, and an 11-34t as having a ‘wide’ gear range).

The range of gears on your cassette, combined with the size and number of your front chainrings, gives you your bike’s gear ratio or ‘gearing’. Bikes that will tackle a wide variety of terrain – on- and off-road – require a wide variety of gears, while professional race/time trial bikes require a narrower range and smoother jumps between gears.

Your cassette, along with other parts of your drivetrain, will wear with time so it’s important to keep it clean and well-lubricated, and to replace when it’s worn out.

If you don’t want to read our in-depth guide on cassettes, you can go directly to the relevant product pages via the links below:

Shop cassette spares

Shop MTB cassettes

Shop road cassettes

Learn more about:
Cassette spares
MTB cassettes
Road cassettes


On modern MTB and road bikes, cassettes are sold as replacement units rather than as individual sprockets. However the special lockring that secures the cassette to your freehub body may require replacement in the event of damage.

If you need to remove your cassette in order to fit a new one or replace the lockring you will need specialised tools including a chain whip and cassette removal tool, as a well as a good adjustable spanner.

Remember to keep your cassette – and the rest of your drivetrain – clean and well-lubricated to extend its life.

Shop cassette spares


MTB cassettes will typically offer a wide range of gears in order to enable riders cope with the varying terrain that they may face – from short, steep technical climbs that require very low gearing (biggest sprocket) to longer descents that can be pedalled fast (smallest sprocket). They typically differ from road bike cassettes in having greater gaps in gearing between each sprocket.

Most MTB bikes use 9- 10- or 11-speed cassettes although more budget models may use 8- or less commonly, 7-speed. A typical gear spread for an MTB cassette (the amount of teeth on the smallest and largest sprockets) would be 11-34t.

When replacing your MTB cassette – rough shifts or frequent chain slippage will tell you that it’s time for a new one – remember that you must get one with the same number of sprockets as your old one. You cannot replace an 8-speed cassette with a 9-speed as the greater number of gears requires a different width chain.

Upgrading your cassette to a lighter model may save you grams, but it will come at a price as top-end cassettes are expensive.

MTB cassettes buying guide

Shop MTB cassettes


Road cassettes typically feature 9, 10 or even 11 sprockets with narrower jumps in gears offering smoother shifts to help achieve optimum cadence (number of pedal revolutions per minute).

Most road cassettes will feature a 12-tooth sprocket as the highest gear with a low gear of between 25 and 32 teeth. A 12-25t road sprocket is regarded as standard, but lower gearing (e.g. 12-32t) is increasingly being specced on bikes aimed at beginners, endurance/sportive riders or just anyone who wants an easier time in hilly terrain. If you do want to avail of a lower gear when replacing a worn cassette, check that your rear derailleur is compatible as larger sprockets may require a long-cage model.

When replacing your road cassette – rough shifts or frequent chain slippage will tell you that it’s time for a new one – remember that you must get one with the same number of sprockets as your old one. You cannot replace a 9-speed cassette with a 10-speed as the greater number of gears requires a different width chain.

It’s also worth noting that while cassettes from two of the three major manufacturers (Shimano and SRAM) are interchangeable, cassettes from Italian maker Campagnolo are specific to Campagnolo drivetrains.

Upgrading your cassette to a lighter model may save you grams, but it will come at a price as top-end cassettes are expensive.

Road cassettes buying guide

Shop road cassettes

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