How Do I Know What Kind of Cassette to Get For My Bike?

The bike cassette offers you a wide gear range to run the chain. That makes it easy to vary your pedaling cadence. For that reason, you should get a suitable replacement when it fails or wears out. But how do I know what kind of cassette to get for my bike?

You can know what cassette to get for your bike by determining the teeth count on the largest sprocket and the smaller sprocket of your current cassette. For example, a size 12-25t cassette, which is standard to road bikes, has 12 teeth on the smallest cog and 25 teeth on the largest cog.  

Note, however, that you have to consider your bike type as not all road bike cassettes suit MTBs, and vice versa.

We’ll talk more about the two cassette types to help you find your match. What’s more, I’ll help you determine the cassette size that you have on your bike.

But before that, let’s understand what a cassette is and what it does.

How do I know what size my cassette is

What is a bike cassette exactly? What does it do?

A bike cassette is a cluster of cogs/sprockets you find on the rear bike hub. It threads onto the freehub and is held in place with a lockring.

The average bike cassette has 5-13 sprockets.

Overall, cassettes provide your chain with a wide gear range to run on, and the gear range varies your pedaling cadence.

A larger sprocket (one with more teeth) offers you easier gear and the power to climb hills. In contrast, a smaller sprocket (one with fewer teeth) means you have to pedal harder.

That’s why it’s advisable to get a cassette that offers you a wide gear range. Such a cassette allows you to pick your preferred torque depending on terrain and how hard you want to pedal.

How Do I Know What Kind Of Cassette To Get For My Bike?

Road Bike Cassette – How You Can Know What Cassette to Get for Your Road Bike

The largest sprocket/cog of a road bike cassette is peculiarly smaller than that of a mountain bike. As a result, it offers small gear jumps.

A majority of road bike cassettes feature 11-13 teeth on the smaller cog and about 21-32 teeth on the biggest cog.

A good number of them come with 12-25t cassettes (the standard cassette size for road bikes).

One cassette with such a size is the Shimano Ultegra R8000 (View on Amazon). It comes with a nickel-plated steel cog material and an aluminum carrier material.

Overall, it’s worth noting the following when getting a road bike cassette:

  • Go for the standard size cassette (12-25t) when planning to ride on flatter roads

A cassette with the size 12-25t offers you enough cadence to cycle on flatter roads. Other than the Shimano Ultegra R8000, you can get the SRAM PG1070 (View on Amazon).

Like the Ultegra R8000, the SRAM PG1070 comes in different sizes, including the size 112-25t.

  • Go for a cassette with a lower ratio when planning to ride uphill

You need more power to cycle uphill, and that’s achievable with a low gear ratio. In that case, consider a cassette with at least 27 teeth on the largest sprocket. That’ll ensure you spin much longer without grinding.

Again, a cassette like the Shimano Ultegra R8000 allows you to get more than 25 teeth on the largest cog.

Other than its standard size 12-25t, it comes in 11-28t, 11-30t, 11-32t, and 14-28t sizes that allow you to conquer the hills.

How Do I Know What Cassette To Buy For My Bike

Alternatively, you can get the LITEONE 8-Speed Cassette which comes in an 11-40t size, perfect for riding uphill.

Not only does the cassette suit road bikes but also MTBs and BMX. The best part is that it’s compatible with Shimano and SRAM drivetrains.

Mountain Bike Cassette – How You Can Know What Cassette to Get for Your Mountain Bike

When it comes to mountain bikes, their cassettes have larger sprockets that vary in size to suit different off-road needs.

Today, having 11-speed, 12-speed, or 13-speed cassettes is becoming a norm for mountain bikes.

Overall, the larger the sprocket number, the easier it is for the bike to conquer climbs.

Note that you need a considerable gear jump to take on the flats and then conquer the climbs. For that reason, you may have to sacrifice a bit of smooth riding and comfort that you get from a road bike cassette.

Today, mountain bike cassettes run on single and double chainsets instead of triple chainsets as it’s used to be in the old days.

That has seen them suffer fewer mechanical issues and becoming lighter and with reduced clutter. Now, we have 10-speed, 11-speed, and 12-speed cassettes with a wide range of large cogs.

The Bibike 8//10/11 Cassette, for example, comes in 11-42t, 11-46t, and 11-50t sizes to suit a variety of 8-11 speed MTBs.

Note, nonetheless, that an 11-speed cassette offers you an extensive sprocket range than its 10-speed equivalent, and therefore, a greater gear range.

Likewise, 12-speed MTB cassettes offer you a greater gear range than preceding cassettes. You’ll, however, need to replace your freehub if you plan to upgrade to a 12-speed MTB cassette.

How to Tell What Bike Cassette You Have

Cassettes are defined by their sprocket number (number of teeth). A cassette generally has two numbers.

The smallest is the teeth count on the smallest sprocket/cog, while the second number is the teeth count on the larger sprocket/cog.

A cassette with 12-25t, the standard road bike cassette, has 12 teeth on the smallest sprocket and 25 teeth on the biggest sprocket.

Overall, the smallest cog represents the higher gear, and it’s generally for fast pedaling. The largest cog, in contrast, represents the smaller gear, and it’s usually for climbing.

What Do The Numbers On A Bike Cassette Mean

How Do I Know What Cassette To Buy For My Bike? (The Buying Guide)

Here are the buying tips for a new cassette:

  • Get the cassette size right

You have to match your new cassette with the old one. In that case, ensure you get the sprocket count correctly.

The smallest sprocket teeth count, and the biggest sprocket teeth count should be correct.

If you want a road bike cassette, go for a size 12-25t for a flatter road and anything more than 27t on the biggest cog for hilly roads.

As for MTB cassettes, ensure you get both the speed and the sprocket teeth count right.

  • Get a compatible cassette

It’s not just about getting the cassette size correctly but also one that is compatible with your drivetrain.

Don’t worry about swapping a Shimano for an SRAM or vice versa, as the two are cross-compatible.  Also, a LITEONE and Bibike cassette are compatible with both SRAM and Shimano drivetrains.

But if you have to get a different brand, ensure it’s compatible with your transmission system first.


1. How Do I Know What Size My Cassette Is?

The secret to knowing your cassette size is determining the teeth count on the smallest and largest cog. Once you do so, you need to get a cassette replacement that matches it.

You can check that from the cassette’s specifications online.

2. What Do The Numbers On A Bike Cassette Mean?

The cassette has two numbers such as 12-25t, 11-25t, 11-40t, or 11-32t. The first number (which is the smaller number) represents the teeth count on the smallest cog.

In contrast, the second number (which is the larger number) represents the teeth count on the biggest cog.

3. What Is The Best Cassette For Road Bike?

Most road bike drivetrains are compatible with 12-25t cassettes, the standard cassette size.

One cassette that fits the description is the Shimano Ultegra R8000, which you can work on any road bike transmission system.

Note, however, that while 12-25t cassettes are best for flatter roads, you need 27 or more teeth on the biggest cog to conquer hills.

4. How Much Does It Cost To Replace A Bike Cassette?

Depending on the cassette size, brand, and type, a decent cassette costs $50-$100 or more, while a budget option averages $20. High-end options, nevertheless, cost up to $500.

Remember, unless you replace the cassette yourself, you’ll also have to incur the labor cost.

And if you have to replace the chain, which often happens when replacing cassettes, you also have to incur its replacement cost, which is about $20.

5. What Does An 11-32 Cassette Mean On A Bike?

The number 11 represents 11 teeth on the smallest cog, while the number 32 represents 32 teeth on the biggest cog.

Overall, an 11-32 cassette offers you a wide gear range.

6. Why Are SRAM Cassettes So Expensive?

SRAM cassettes are generally expensive because they are designed for high-end bikes. They are made of high-quality materials to promise better performance and lasting use.

Plus, the cassettes are mostly lighter than the competitors.

Relevant: Can You Add Gears to a Fixed Gear Bike?

Closing Thought:

So, how do I know what kind of cassette to get for my bike? As discussed, you must determine the teeth count on both the smallest and largest cog.

Doing so allows you to find a cassette replacement that matches your original cassette and drivetrain.