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You might not notice for some time that the hub on your wheel is riding rough. Your riding will most likely feel “off” in some ways. How can you sort this out?
Rear hubs are normally pretty easy to fix on mountain bikes. There are two main types:
- Cup-style mountain bike hubs
- Cartridge-style mountain bike hubs
In this post, I’ll take a look at how you can first identify that you have a problem with your rear hub. Then I’ll show you how you can troubleshoot what the issue is. Then I’ll talk you through a step-by-step guide on how to repair the two different types of hubs (cup-style and cartridge-style).
How To Know That You Have A Problem With Your Rear Hub
First, how do you know you have a problem with your rear hub?
Cornering will feel clumsy, and going downhill will feel shaky. Shifting may not be right on the back wheel.
You might even feel as well as hear a “clunk” that seems to come from your rear suspension (regardless of whether it is a fork or shock variant).
You might find that toughening your quick-release skewers seems to help for a little while, but the problems come back quickly.
If your bike wheels feel harsh when you rotate them, it is time to take care of your hubs. Most of the time, the problem is caused by worn bearings or dirt and water getting in. Wheel joints also deteriorate over time, which causes the hub to become loose and lets the wheel move back and forth on its rotor.
Hubs usually have two types of bearing surfaces: sealed (cartridge) and not sealed variants (cup and cone, or loose) of bushings.
Service can make them last longer, but they will wear out to the degree where the only option ends up being replacing them.
Hub Repair for Cone and Cup Style Mountain Bike Hubs
What are the Tools I require?
You will only require the following tools:
- Mainly 15mm and 17mm cone-spanners
- A magnetic screwdriver
- A chain-whipper
- A tool to take out the cassette
an adjustable crescent wrench
- Grease remover
- Clean rags or paper cloths
Step 1: Removing your Lock Nuts (Also known as Lock Bolts!)
First, take the cassette off the body of the freehub.
When you change your cassette, you can also change your gearing, thereby making it safer or tougher for the terrain where you live or for a certain event.
For all of these reasons, your cassette (and maybe your chain) will have to come off. Take off the lockring, and afterward pry the old cassette in your direction to get it off the freewheel.
If you wish to keep the cassette you are replacing, you should zip-tie everything together and in the right order.
Use a cone wrench to grip the disc and a second one to loosen the lock bolt on the side that is not the driver’s side. By hand, take off the fastening nut and the spacer.
To make it easier to put back together later, it is best practice to write down the sequence of the locking screw and any threaded inserts are taken off (Source).
You could also take a picture with your phone. With one spanner, grab the lock bolt on the front side. With the other, loosen the cone on the side that is not the driver side.
Now, you should be able to pull the axle out of the hub.
Step 2: Remove and Clean the Bearings
Carefully take the bearings off the race. The edge of a magnetostrictive screwdriver will assist you to lift the bushings/bearings out.
The next step is to tidy up the bearings. Use any degreaser spray of your choice and a paper towel, and make sure you get all the old excess oil off before moving on.
Look closely at the bearing surfaces, the cups (that are squeezed into the hub), and the cylindrical cones.
If they show any signs of wear, they will need to be changed (Source).
Step 3: Reapply Lubricant on your Hub
Take some lubricant and put a lot of it on the hub’s bearing race. Now you can put the rollers in the grease, which will help them stay put.
Once more, this task is so much easier to do with a magnetic wrench or screwdriver.
Once each of the bearing surfaces is on spot, you can put the axle back on and turn it gently to make sure they are located in the right place. Take off the axle and do the same thing on the opposite side.
Step 4: Refit the Axle into its Position
Now put the axle back on the side with the free hub.
To make sure it is reclined correctly, push it into the bearings and turn it.
Put the cone back onto the side of the driveshaft and toughen it until it touches the bearings. It does not have to be very tight, just finger-tight would do.
Then you can turn the axle to ensure it spins smoothly. Start giving the axle just that little bit of a shake to make sure there is no play left.
You might need to change how tight the cone is to get rid of any play or drag. If it is too tight, the hub won’t be able to turn freely.
On the other hand, if it is too loose, the axle will move around.
This step requires some experimentation, but do not rush it because a hub that is not set up right is likely to result in problems down the road.
Rever the other nuts, spacers, and seals to the side of the axle that does not move. Check your notes to see how you took them off.
Then, while still holding the cylinder cone in its original place, use the second wrench to stiffen it to the locking nut.
At this point, it is important to make sure the axle can still turn freely because it is easy to fasten the cone as well during this process.
Step 5: Refit the Cassette
Then, put the cassette back on the freehub body and put the quick-release skewer back on.
For Cartridge Style Mountain Bike Hubs
What are the tools I Will Need?
You will require the following tools:
- Cone spanners of various sizes (13, 14, 15, and 16mm)
- Unlocked 15mm spanner
- 5mm Allen keys
- Solid replacement axle for the back wheel
- Nylon (or resin) mallet
- A small screwdriver (Preferably magnetic)
- Bearing lubricant
- Specialized equipment or alloy tubing is required to press the bearings.
Step 1: Remove your Dust Caps
You will need to remove a detachable dropout aid or locknut from at least one side of the shaft of your hub.
In the majority of instances, this may be accomplished by putting a 5mm Allen wrench at it from both ends and rotating counterclockwise.
Utilize a small cheat bar or a lengthy hex bar for this task, since it may require physical exertion.
Maintain a record of all washers and their placements between both the spacers and the axle. In most hubs, the silver spacer serves as both a dust stopper and a cosmetic feature.
It may need some effort to remove since it is likely kept in place by a silicone O-ring that connects it to the axle’s groove.
Alternately, certain hubs include a threaded cap that permits bearing adjustment; just remove these caps first. Others employ a simple interference fit cap. Refer to the manufacturer’s instructions for specifics.
Step 2: Remove the Old Bearings
To remove the bushings, you must first hold the hub in a manner that prevents it from being damaged. You could, for instance, use a Delrin pipe.
A few quick hits will be required to release the bearings, thus a rubber maul will likely not be enough; a resin hammer or a wooden board with a lump mallet are considerably more effective at imparting the necessary power to dislodge it.
Step 3: Remove your Second Bearing
The following procedure removes the remaining bearing.
Rotate the wheel over again and insert the bearing with the hub pointing down. Ensure that the hub is properly supported by the flanges and that the bearing can be removed.
Place the axle or an appropriate drift tool (an aluminum tubing or an old steel axle with a conical or nut partly threaded onto it would do) and strike the bearing with several strong blows.
Be careful that you may need to strike it with considerable force if the fit is tight.
Cleanse the entire hub with a good degreaser and cloth, as well as the hub flanges surrounding the spoke connection points; you do not want dirt to enter the bearing seating when reinstalling the hub.
Examine the hub flanges, especially around the spoke holes, for fractures or corrosion.
If cracks are seen, a new core or wheel will be required.
Step 4: Put Your New Bearings into Place
Spread a thin layer of grease over the exterior and interior surfaces of the replacement bearing surfaces, the interior of the hub shell, and the axle.
If the grease between both the bearing as well as the hub is excessively thick, it might prevent the bearing from being seated fully.
The replacement bearings must only be pushed by its outer race since contact with the inner race might harm the little ball bearings within the cartridge.
Utilize your older bearing that is being replaced or a socket with the same width to install the new bearing. Bear in mind that load-carrying races are made of hardened steel, making them potentially fragile.
Wear eye protection and ensure that the interface area between the drift blade and other racing edges is maximized by ensuring that they are completely aligned.
The bearing is properly installed when the strikes suddenly become hard. Investing in a bearing presser is the finest option for this task by a wide margin and is highly recommended.
Install the shaft/axle, place the second bearing, and then tap it into place.
Do not allow the bearings to be installed crookedly, as forcing it in if it is severely out of alignment will simply jam it and make it more difficult to install.
It is also likely to cause ridges that might prevent it from fitting properly or perhaps irreparably harm the hub. Thread the dusty caps firmly on with a small amount of oil, and then check for that silky fluidity in your rotations.
Step 5: Rejoice in your New Hub
“The perfect amount of wiggle is merely a little bit more than no play,” says one hub maker.
What this means in real life is to tighten the cone nuts and spin the wheel while holding the hub axle with both hands.
You should not feel any agitation, but you should not feel any wobble either. This is usually the same as tightening the cone all the way and then supporting it off between 1/16 and 1/8 of a turn, but it depends on the hub.
How do Mountain Bike Rear Hubs Break?
Bicycle wheel connectors can be of the cup and cone or cartridge style, the latter of which cannot be changed (Source).
The load-carrying play can be changed on the bearings of the extendable types we discussed earlier. Most types of cartridges cannot be changed for wear or performance. Both can have either one “freehub freewheel” or a “thread-on freewheel”.
Here’s how a basic load-carrying system works: most of the time, the cup is pressed into the center shell and stays there.
The ball bearing is caught by the cone. Tightening the fastener against the cone keeps the cone from shifting. If the bearings are loose, you can move the cone pretty close to the cup.
Troubleshooting for Problems
Examine the hub cups as well as cones for corrosion or pitting. Use a sharpie pen to sketch the bearing’s course as well. You will feel hardness and roughness as the little tip of the pen rolls over pits.
Examine ball bearings for luster and brilliance. If balls have lost their polish, they should be changed.
Generally speaking, a damaged cup cannot be replaced. A new node would be necessary. Typically, cones are accessible as replacement components.
To check a wheel axle, roll it on a level surface. Observe the axle near the surface and wait for a gap to form as the axle rolls. Twisted axles can sometimes be re-bent.
A replacement axle is often your best bet though.
Here is the video explainer on how to Service Hub Bearings: How to Service Hub Bearings | More Efficiency & a Smoother Ride!
The Bottom Line
There you are! Your hub is now ready to go. We hope this article helps you fix all your mountain bike rear hub-related problems. As always, be safe and happy riding!