Shimano freehub replacement

Shimano freehub replacement is a necessary task for any cyclist who has noticed that their bike’s rear wheel is no longer engaging properly or is making strange noises when coasting. 

Replacing a Shimano freehub is a process that involves removing the old freehub from the wheel, installing a new one, and then reassembling the wheel. It is important to choose the correct replacement freehub for your specific wheel, as not all Shimano freewheel bodies are compatible.

By following the correct procedures and taking the necessary precautions, you can replace a Shimano freehub and get your bike back up and running smoothly. In this guide, we will outline the steps involved in the process, including what tools you will need, how to remove the old freehub, how to find the correct replacement, install the new freewheel body, and how to reassemble the wheel.

Definition of a freehub body

A freehub body can be found on the rear wheel of a bicycle and it allows for the attachment of the cassette. The cassette contains the gears of the bike’s drivetrain.

Reasons for replacing a freehub body

Over time, the freehub body may wear out or become damaged, which can cause issues with shifting or can lead to the cassette slipping or skipping. In such cases, it may be necessary to replace the freehub body in order to restore the proper function of the wheel and the bike’s drivetrain.

• Worn out or damaged pawls: The pawls are the small teeth inside the freewheel body that engages with the ratchet mechanism to provide resistance when pedaling. Over time, the pawls can wear out or become damaged, causing the freewheel to slip or not engage properly.
• Worn out or damaged ratchet mechanism: The ratchet mechanism is part of the freewheel body that engages with the pawls to provide resistance when pedaling. Like the pawls, the ratchet mechanism can wear out or become damaged over time, causing the freewheel to slip or not engage properly.

Overall, changing the freewheel body on a bike wheel can help improve performance and extend the life of your drivetrain. 

Finding the correct Shimano freehub replacement

It is important to choose a freewheel body that is compatible with your Shimano hub.

• First, check the rear hub model number. You may need to clean the hub body first to be able to see the model number clearly.

• Go to the si.shimano.com website

• Type the model number in the search box.

• Choose the EV (exploded view) PDF file.

• Find the freehub body and copy its code.

• Paste the code into your web search and the sellers with the exact part will be listed.

List of required tools

• Cassette removal tool- This slots into the lockring of the cassette and some disc rotors. Some of the tools are equipped with a lever so you don’t need a spanner.
• Chainwhip- This tool holds the cassette steady while undoing the lockring.
• Spanner- This needs to be big enough to fit onto the cassette lockring tool.
• Lever/jolly bar- This goes over the wrench and/or chain whip to add leverage when undoing the cassette’s lockring.
• External bottom bracket tool, T25 or 3mm allen key. One of these tools is required to remove the disc rotor. 
• Flathead screwdriver. May be useful when removing the rubber cover from the axle.
• 17mm spanner and 15mm cone spanner. These tools are essential when removing and tightening the lock nut and the cone.
• 10 mm allen key. Used to unscrew and tighten the freehub body
• Magnetic pick-up tool. Great for picking loose ball bearings from the hub.
• Cloth or paper towel. Use this to clean the area around the freehub body
• Grease. This is used to grease the ball bearings in the freehub body
• Vice. Not essential but it makes the job much easier.

Preparation

• Remove the wheel from the bike. Our article here will help you with this task.
• Remove the quick-release skewer or the wheel nuts.

• Now remove the cassette from the wheel. If you’re not sure how to do this our article here will guide you through this process.
• If there’s a disc rotor then undo the 6 bolts or lock ring and remove the rotor.

When removing the disc rotor make sure that you don’t touch the braking surface. Your skin contains oils and other contaminants that can reduce the performance of the braking system. Touching the braking surface can transfer these contaminants to the rotor surface and then onto the pads.

Removing the Shimano freehub

• If you have a vice then clamp the freehub side of the wheel in it.

• Fit the 15mm cone spanner on the cone and hold it in place.

• Fit the 17mm spanner on the lock nut and undo it anticlockwise.

• Remove the lock nut, the spacer, and the left-hand side cone from the axle.

• Gently remove the axle. 

• If you work on the vice then lift the wheel and the axle will stay in the vise.

• Use the magnetic pick-up tool to remove the loose bearings from both bearing cups and set them aside.

There should be 9 1/4″ loose ball bearings in each cup.

• Now fit the 10mm allen key in the freehub body and undo the freehub body fixing bolt anticlockwise.

• Remove the bolt from the freehub.

• Remove the freehub body.

• Remove and clean the freewheel body washer.

• Clean the area of the hub where the freewheel body is attached.

• Clean the axle, the cones, and the bearings and check them for wear.

• If required replace them with compatible parts. Use the codes from the Shimano.si pdf file to find the correct replacement.

Fitting the new Shimano freehub

• Place the freewheel body washer.

• Fit the new freehub body, making sure that the splines on the freewheel body engage properly with the splines on the hub.

• Slide the fixing bolt into the freehub and, using a 10mm allen key, screw it clockwise, making sure that it’s tight. 

• Grease the freehub’s bearing cup and fit the ball bearings. 

• Add a bit of grease on the top of the ball bearings and clean the excess grease from the freehub body.

• Now clean the cup on the non-drive side and replace the bearings.

• Slide the axle into the hub.

• If you use a vice, slide the wheel on the axle.

• Install the cone. Screw it with your hand until the cone contacts the bearings.

• Fit the spacer and the lock nut.

• Fit the 15mm cone spanner on the cone and hold it in place.
• Fit the 17mm spanner on the lock nut and tighten it clockwise.

• Check if the axle spins smoothly but there is no play.

What to do if the axle doesn’t spin freely?

• If it doesn’t spin smoothly then put the wheel between your legs so that the hub is on the right-hand side.

• Fit the 17 mm spanner on the lock nut on the drive side and hold it in place.

• Now fit the 17mm spanner on the lock nut on the non-drive side and turn it anti-clockwise a quarter of a turn.

• If you use a vice then undo the lock nut and with a 15mm cone spanner undo the cone anti-clockwise quarter of a turn and tighten the lock nut.

What to do if there’s a ply in the wheel hub?

• If there’s a play in the wheel hub then put the wheel between your legs so that the hub is on the right-hand side.
• Fit the 17 mm spanner on the lock nut on the drive side and hold it in place.
• Now fit the 17mm spanner on the lock nut on the non-drive side and turn it clockwise a quarter of a turn.

• If you use a vice then loosen the lock nut and with a 15mm cone spanner tighten the cone clockwise quarter of a turn and tighten the lock nut.

• Check the wheel again and repeat the process until you are happy.
• Install the disc rotor, the cassette, and the quick release.

• Now, fit the wheel. We have a great video here if you struggle with this task.
• Finally, spin the wheel to check if the new freehub has been installed correctly.

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