I am getting my mountain bike ready for spring and, after taking it for a quick ride, I am realizing that the chain keeps slipping. This is happening when I change gears and sometimes just when I am riding normally. Below are the instructions on how to install a new cassette on a mountain bike.

  1. Purchase a new cassette.
  2. Gather your tools.
  3. Remove the wheel from the bike.
  4. Remove the lock ring.
  5. Remove the old cassette and replace with the new one.
  6. Replace the lock ring and remount the wheel.
  7. Look below for detailed instructions if necessary.

How to Replace the Cassette on your Mountain Bike.

First off, the tools you will need are…

  • A lock ring removal tool. (specific spec for your model is described below)
  • A chain whip.
  • A 1” wrench. (unless you have the FR-5H lock ring removal tool)
  • Grease/Anti-Seize

Tools can be SUPER EXPENSIVE if you buy them individually. I bought a tool box full of the most popular items needed. Check out what I recommend in this article. Best Tool Kit for Mountain Biking

To remove your old cassette…

  1. First you have to determine if you have a cassette style cog system or a freewheel style. This is actually quite simple and only requires you to spin the cog system with the wheel off of the mountain bike. If the innermost tool fitting spins along with the sprockets then your mountain bike has a cassette style cog system. If the innermost tool fitting does not spin along with the sprockets then you have a freewheel style cog system.
  2. Assuming you do in fact have a cassette style cog system the next step is to determine the lock ring removal tool necessary for your mountain bike. If you have a Campagnolo rear derailleur then you need to use a Bbt-5/ Fr-11 lock ring removal fitting. If you have any other brand you will need to use a lock ring remover from the FR-5 series.
MTB cassette remove tool
MTB cassette remove tool
  • The FR-5.2 is only the socket and will need to be used in conjunction with the nut from your skewer style axle to be held in place. This is done by first placing the socket onto the lock ring and then tightening it down with the nut from your skewer axle.
  • The FR-5.2G has a guild pin built in to eliminate the need for the nut from you skewer.
  • The FR-5.2GT has a 12mm guild pin to accommodate thru-axle style mountain bikes.
  • The FR-5H has a handle which eliminates the need for a 1” wrench to turn the lock ring removal tool.
  1. Secure the sprockets of your mountain bike by placing the fixed side of your chain whip onto the sprockets and the wrapping the loose end counter clockwise around the sprockets.
  2. Now use you lock ring removal tool, turning it counter clockwise, to release the lock ring. This now gives you access to the cassette of your mountain bike.
  3. Remove the old cassette. Sometimes a spacer will be found on the back side of the old cassette. If you will be reusing your old cassette then this spacer along with the old sprockets can be tied or zip-tied together as to maintain their original order and keep them all together.
  4. Align the keyed splines of the freehub body to that of the splines on the new cassette and then gently slide the cassette into place.
  5. Grease the threads on the inside of the freehub body.
  6. Use the same locking tool for before to twist the locking clockwise to fully secure the cassette into place. The recommended force to tighten the lock ring is 40 Newton Meters). If any of the sprockets are loose then it is most likely that a spacer has been removed.
  7. Remount the wheel to your mountain bike.

A quick note to remember is that if your bike has a SRAM XD cassette system then it will not have a locking but will still require a FR-5 series lock ring removal tool to remove from the mountain bike. This is because there is a portion of the cassette which your FR-5 series tool will be able to gain purchase on to tighten the cassette to the freehub base. Additionally, you will have to grease the threads on the inside of the cassette as opposed to those in the freehub body.

What is a Cassette on a Mountain Bike

The cassette is the sprocket portion of the drivetrain of your mountain bike. Different size sprockets in the cassette provide different amounts of force need to propel the mountain bike, of course putting different amounts of force to the wheel itself. The Cassette is held to the bike by a lock ring and encases the main skewer or thru axle on one side of the bike. Traditionally it will be found on the right side of the rear tire in the center of the spokes.

MTB Tools I Love and Recommend

Bike Hand Repair Stand
Bike Hand Repair Stand
Bike Hand 37 pcs Tool Box
Bike Hand 37 pcs Tool Box
Topeak Smartgauge D2 Air Pressure
Topeak Smartgauge D2 Air Pressure

I own each of these tools and only recommend things I own and use.

  • Bike Hand Bike Repair Stand.  Nice mountain bikes don’t have a kick stand so keeping your MTB safe but conveniently stored is essential.  I keep my bike on my stand whenever I’m not riding it.  This makes it easy to lube the chain, inflate the tires and adjust the derailleur.  Highly recommended – Bike Hand Bike Repair Stand (👈 Link to Amazon to see what thousands of others have said)
  • A basic MTB toolbox for replacing a chain, adjusting brakes and dialing in the fit.  Bike Hand has a 37-piece box that has most of the specialty bike tools to keep your MTB properly maintained.  The Bike Hand brand is value packed for the avid rider.  Check out the competitive prices with this link to Amazon 👉 Bike Hand 37 pcs Bike Repair Tool Kit
  • Get a good air pressure gauge, if you get just a tiny bit serious about MTBing you’re going to start playing with tire pressure.  A couple psi can make your tires sticking or not.  Get a good gauge, I highly recommend the Topeak Smartgauge D2, it’s accurate, flexible and easy to use.  An Amazon best seller, here’s a link 👉 Topeak Smartgauge D2
  • Carry a multitool with you on every ride.  I’m serious, most of the time you can MacGyver something to get back to the trailhead if you have a multitool.  I’ve got the Crank Brothers M19, it’s worn, rubbed and abused – but it still works.   Thousands sold on Amazon – check it out with this link 👉 Crank Brothers M19

How to Replace the Cassette on your Mountain Bike Without any Special Tools

To remove the lock ring of your mountain bike without a FR-5 series lock ring removal tool or a chain whip the following steps can be taken.

  1. Either…
  • Use an old chain that has been cut by placing it counter clockwise onto the sprockets. Holding down the other end of the chain with your foot.
  • Put a chain onto your bike and use the force from the peddles to create tension on the lock ring.
  1. Insert a pair of needle nose pliers into the splines of lock ring and open them as far as possible to create tension.
  2. Using another pair of pliers attached horizontally to the head of the needle nose pliers, twist the needle nose pliers counter clockwise. This should break the lock ring free and allow you access to the cassette of your mountain bike.
Using a store bought chain whip to remove a cassette
Using a store bought chain whip to remove a cassette

Can you use Different Branded Derailleurs and Cassette together?

While there are some cases is which derailleurs are compatible across brand it is unwise to mix and match brands of cassettes and derailleurs. This is because all of the major Mountain bike drivetrain brands use different pull ratios in their derailleurs. This means that the amount the chain will move in-between gears varies depending on the brand of your derailleur. As you could imagine this would cause a lot of problems for you. This is why it is the safest option to not mix and match drive train component brands.

What is the Difference Between a Mountain Biking Cassette and a Road Biking Cassette?

In general, mountain biking cassettes have a much larger number of sprockets total in the cog system which allows for a better range peddling difficulty. This is incredibly important when mountain biking if you are dealing with terrain that is constantly changing in elevation or traction.

However, this means that to accommodate for all of these extra sprockets the space between each sprocket greater than that of those generally found on road bikes. This means that you will experience gear shifts that are not a smooth as you have some to expect from a traditional road bike. Road biking cassettes, conversely, do to not need to accommodate for these things.

What Size Cassette does my Mountain Bike need?

While you need to buy the same brand cassette as is your derailleur, there is another specification you must keep in mind. When replacing the cassette on your mountain bike you need to replace the old cassette with a new cassette that has the same number of sprockets as the old one. You cannot replace a 9 speed with a ten speed or inversely a ten speed with a nine speed.

Are MTB Derailleurs Compatibile?

How much to replace MTB Derailleur
How much to replace MTB Derailleur

Shimano Mountain Bike Derailleur Compatibility

All 11, 10, and 9 speed mountain biking derailleurs are inter-compatible with their respective 11, 10, and 9 speed mountain biking components. It is important to note that Road biking and Mountain biking Shimano components are not compatible as they have different cable pull ratios.

SRAM Mountain Bike Derailleur Compatibility

All 7, 8. And 9 speed derailleurs are inter-compatible with the respective 7,8, and 9 speed biking components regardless of whether or not they are road biking or mountain biking components.

10 speed components are inter-compatible

10 and 11 speed mountain biking components are not inter-compatible

10 and 11 speed road biking components are inter-compatible.

Campagnolo Mountain Bike Derailleur Compatibility

8 and 9 speed Campagnolo group sets manufactured prior to mid-2001 use the same pull ratio and are compatible with each other. Parts made during this period are called “Campy old” parts.

Parts manufactured after “Campy Old” use a revised pull ratio for the new 9-speed kit, and all 10 or 11 speed) group sets from this period are inter-compatible.

However, changes in Campagnolo’s manufacturing has resulted in changes in all of their group sets. For newer Campagnolo parts the best way to determine compatibility is to ensure that All of your parts have the same letter etched into them. There will either be an “A” or a “B” etched into the metal somewhere onto the product.

How Long does your Derailleur Cage Length Need to be?

Huffy Rear Derailleur
Huffy Rear Derailleur

For most Mountain bike Cassettes and other large sprocket set cassettes a long Cage length derailleur is recommended. This is because it will be able to take up a large amount of slack in the chain which will allow for smoother switching if gears from a large sprocket to a small one.

For some larger road biking cassettes, a medium length cage is recommended. This will allow for slack to be taken out as mentioned before but will also ensure a secure fit on your bikes chain.

For regular road bikes with only small differences between the largest sprocket and the smallest sprocket a short length cage is recommended. This is because since not much slack is needed to effectively change gears it is better to use a short length cage. This will ensure your chain is secure onto your cassette and your main drivetrain sprocket.

MTB Derailleur Tooth Capacity

To further ensure compatibility between your cassette and derailleur you need to determine the required tooth capacity of your cassette. To do this you must take the largest cog and subtract the smallest cog then add the largest chainring minus the smallest chainring. This will result in the Required capacity.

One of those MOST beneficial things you can do is Maintain your drive train. I’ve written a detailed set of instructions with a FREE download. Here’s a link to the article. DIY Mountain Bike Maintenance Schedule Guide

Looking for Some More Ways to Help Your Bike Last


David Humphries is the creator of DIY Mountain Bike. For me a relaxing day involves riding my mountain bike to decompress after a long day. When not on my bike I can be found wrenching on it or making YouTube videos at 👉 DIY Mountain Bike Read more about David HERE.