The rear hub is the most crucial part of mountain bikes, which lets you transfer force from the pedals to your bike and, this part bears more impact than any other part. The rear hub absorbs rough terrains and carries most of our body and bike weight so, this part should work all the time perfectly. Slightly change in the rear hub, and you will feel the difference in riding.
Bearings are the most neglected components which make bikes move. Almost everything in a mountain bike which rotates has a basic bearing system such as the rear hub, front hub, drivetrain bracket, pedals, and shock absorbers pivot. A small component in the rear hub makes the wheel move freely, known as bearing balls.
Generally, there are two types of ball-bearing for the front and rear hubs:
- Cup and Cone-Style Bearings
- Cartridge Bearings.
Cup and cone bearings are serviceable, while cartridge bearings are non-serviceable. Cup and cone bearings have removable dust caps, while cartridge bearings are non-removable seal – it is fully packed.
The bearing ball usually wears out after a year. It depends upon your riding track and distance. Cup and cone hub wear out quickly on wet trails. A worn-out ball bearing makes the wheel wobble, and you will need to tighten the wheel after reassembling the ball bearings.
In this article, I will elaborate on How to tighten the rear hub on mountain bikes and service cup and cone style bearings. This guide will help you disassemble, service quickly, and reassemble the rear wheel step by step.
What tools I Need To Adjust Rear Hub
- Cone wrenches ( small size are best suitable )
- Axle vise (to hold wheel tightly in one place)
- Adjustable wrenches (x2)
- Magnet Screwdrive
- Wire ties
- Wet Rags
Cup and Cone Style Bearing Hubs
Cup and cone style bearing hubs have five most essential usually found in every bearing; modern freehubs are more complex and have some extra parts.
- Lock nut
- Bearing Race
- Axle / axle nut
Cup is non-removable and fixed to the hub core. If the cup is damaged, then you have to replace the whole hub. While other parts balls, cone locknuts, washers are serviceable and replaceable.
1.Disassemble the Hub Overhaul
- Mostly mountain bikes have a quick-release liver instead of axle nuts; up this liver to remove the cassette if it has axle nuts, then use a wrench to unscrew it – you may need a vise to hold the other end of the axle tightly.
- Use the measuring tape to note the amount of axle sticking out from both sides – Usually, it’s around 20mm.
- Remove any rubber cover or washer.
- Use a cone wrench to hold the cone and loosen the locknut by rotating it counter-clockwise – It may need to apply some force.
- Remove the cone by rotating it counter-clockwise using a cone wrench – you will see ball bearings inside the cup.
- Now remove the cone and locknut on the right side – both sides may not be identical but get confused; this is due to the cassette cogs on the left side.
- Measure the protruding amount of axle from both sides. Both are usually different.
- Pull out the axle and inspect if there is any dent on it;
- Use a magnetic screwdriver or pencil magnet to lift the ball bearings inside the cup on both sides.
- Many cups and cone hubs have a dust cap seal that is removable but fragile; try to remove it using a screwdriver – don’t apply too much force pull out from all sides gently until it comes out.
- Clean all the parts using a damp cloth – don’t use any chemical solvent.
2. Replace the Ball Bearings
First, check the ball bearings. Wipe all the grease off them and check if they are shining and look fine. If the bearing ball is looking dull or damaged, you have to replace it. Count the number of bearing balls on each side and replace them with an equal amount.
Bearing balls have different sizes but the same size and quantity of ball bearings – (mountain bikes usually have quarter ball bearings and nine balls on each side)
3. Inspect the Cone and Axle
Inspect the cone using a ballpoint; point the ballpoint tips on the bearing path of the cone – you will feel roughness and wear on the ball bearing track.
Now it’s time to inspect the axle, keep it on a flat surface, and roll on it. Check the gaps between the axle and the surface while rolling it. Check the axle thread. If the axle moves smoothly without bumps, it is working fine.
4. Final Touch
Inspect other components like washers, spacers, and nuts; there should be no wear and tear. A washer may not seem an important part, and you neglect that, but these are important to keep the hub tightly in one place.
You can check the nut thread and roll them on a flat surface like an axle. Sometime derailleur bring some issues during fixing, you can also read article by Tom Fortune on Adjusting front derailleur.
5. Reassemble All the Components
- Apply the grease on all components except washers
- Put more grease inside the cup and put the noted number of balls bearings inside the cup symmetrically – keep the ball in a circular line.
- Cover with dust cap gently.
- Install the right side of the hub first – Keep the same amount of protruding axle which you measured earlier – keep the locknut at that point, then tighten the other parts – washers cone and cup.
- Put the axle inside the hub – now you have installed one side.
- Now install the other side – you don’t have to adjust the protruding amount on this site as it will adjust correctly if you keep the other side correct.
- The hub cones should be snugged into the ball-bearing cub until it contacts them, then turned 90 degrees counter-clockwise.
What is the difference between through axle and quick release?
The quick-release skewer has a small size with a 5mm rod; it has a lever on one side of the hub. You can easily remove the wheel by pulling the lever up. You can remove the wheel by pulling out the axle.
While thru-axles are larger up to 20mm, usually, mountain bikes have a thru-axle. It also has a camming lever on one side, but the other side is fitted on the fork l, so you have to put out the axle to remove the wheel.
How do you service a Shimano hub?
Shimano hub uses cup and cone style bearing serviceable ball hubs so. You can quickly service a Shimano hub by following a cup and cone style ball bearing makeguide elaborated above. You may have to change the balls inside the cup or clean all the components.
Can you over-tighten through the axle?
Tighten the axle clockwise direction; don’t try to over tighten the axle. It will damage the threads of the axle and sprockets. Just make sure that the axle is snugged to the cassette and cone into ball bearings tightly.
Should you grease through an axle?
Yes! Always apply grease to the axle. It will make the axle remove and fit easily. It also prevents the axle from rust and corrosion. Although, it is compulsory to put grease on the axle.
Loose hubs make riding too much complicated. It makes your bikes wobble when pedaling and can make you fall while turning. Even a tiny amount of wobbling creates fatigue while depending. So, it would be best if you tightened your rear wheel as soon as possible; otherwise, it will also wear out your rims.
Disassembling and reassembling the rear wheel hub is a technical task. You have to keep all the components in a balanced way after disassembling. After service and replacement, reassembles the parts on the same line. If you have all the necessary tools, it will hardly take 30 – 40 minutes to tighten loose bearings and tires.