How to Replace a Bike Hub: A Comprehensive Guide

Replacing a bike hub might seem like a daunting task, but with the right tools, patience, and a step-by-step guide, it’s a manageable project for the dedicated home mechanic. This comprehensive guide will walk you through the process, from understanding why you might need a new hub to the final touches of reassembling your wheel. Whether your current hub is damaged, worn out, or you’re looking to upgrade to a higher-performance model, this article will provide the knowledge and confidence to complete the job.

Why Replace a Bike Hub?

Before diving into the how-to, let’s consider why you might need to replace your bike’s hub. Here are some common reasons:

* **Damage:** Cracks, bends, or severe impacts can compromise the structural integrity of the hub, making it unsafe to ride.
* **Worn Bearings:** Over time, the bearings within the hub can wear out, leading to rough rotation, increased resistance, and even play in the wheel. This is often accompanied by a grinding or clicking noise.
* **Upgrade:** You may wish to upgrade to a higher-quality hub for improved performance, better sealing against the elements, or compatibility with new components.
* **Compatibility:** If you are changing your drivetrain or brakes, you may need a different hub that fits the new cassette or disc rotor mounting style.
* **Corrosion:** In some environments, hubs can corrode, weakening them and affecting performance.

Tools and Materials You’ll Need

Before you start, gather all the necessary tools and materials to ensure a smooth process. You will likely need the following:

* **New Hub:** Make sure you have the correct hub that matches your wheel’s spoke count, axle type (quick release or thru-axle), and brake type (rim or disc).
* **Spoke Wrench:** Correct size for your spokes. These come in various sizes, so ensure you have the correct one.
* **Spoke Tension Meter (Recommended):** While not strictly necessary, a spoke tension meter is highly recommended for building a properly tensioned and durable wheel. Using one will dramatically increase the lifespan and performance of your wheel.
* **Nipple Driver/Spoke Tool (Optional):** Can speed up the process of screwing spoke nipples onto spokes.
* **Wheel Truing Stand (Optional, but Recommended):** A wheel truing stand makes it easier to check and correct any lateral or vertical deviations (trueness) in the wheel after the rebuild.
* **Tape Measure or Ruler:** To measure the old hub and rim’s dimensions.
* **Camera/Smartphone:** Take pictures throughout the process to aid in reassembly if needed.
* **Grease:** For the hub bearings and spoke threads.
* **Gloves:** To keep your hands clean.
* **Work Area:** A clean and organized workspace.
* **Pen and Paper:** To take notes and measurements.
* **Spoke Calculator/App (Optional):** To calculate the correct spoke length for a new hub and rim combination.
* **Optional:** A spoke holder, often called a third hand tool, can be very helpful when relacing a wheel
* **Optional:** A small mallet or rubber hammer can sometimes assist with gently removing and seating bearings and axles.
* **Appropriate tools for removing brake rotors or cassettes** if those are mounted on the hub

Step-by-Step Guide to Replacing a Bike Hub

Now, let’s get into the nitty-gritty of replacing your bike hub. This is a detailed process, so take your time and be meticulous.

Step 1: Preparation

1. **Clean Your Bike:** Before starting, clean your bike, especially the wheel and hub area. This will prevent dirt and grime from getting into the new hub.
2. **Remove the Wheel:** Take the wheel off your bike. Release the brakes (if rim brakes) or loosen the thru-axle/quick release mechanism. If the bike has a rear cassette, make sure you know how to remove the cassette, as it may be attached to the hub you are removing.
3. **Remove Tire and Inner Tube:** Deflate the tire completely and carefully remove it and the inner tube from the rim.
4. **Remove any brake rotors, cassettes, etc** These are attached directly to the hub and will need to be removed to perform the replacement.
5. **Photograph Everything:** Take several pictures of the existing wheel setup before you start taking things apart. This will be invaluable for reference when you’re putting it all back together, paying particular attention to the way the spokes are laced.

Step 2: Recording Hub Dimensions

1. **Measure and Record:** Before disassembling the wheel, accurately measure and record the following dimensions of your old hub and rim. You can use a tape measure or ruler to take these measurements. Document the measurements with your pen and paper. In some instances, you may be able to find these numbers online, but it’s still a good idea to measure them to be sure.
* **Over Locknut Dimension (OLD):** The distance between the outside faces of the locknuts on the axle. This determines the hub width and must match your frame or fork.
* **Flange Diameter:** The diameter of the circles where the spoke holes are located on each side of the hub. Note the diameter of both the left and the right flange as these may be different sizes.
* **Flange Distance (Center to Flange):** The distance from the centerline of the hub to the center of the spoke holes on each flange. Note the left and the right flange distances as these may be different.
* **Spoke hole diameter** The size of the hole the spokes pass through.
* **Rim Effective Rim Diameter (ERD):** The inner diameter of your rim as defined by the manufacturer. You can find this number on the manufacturer’s website or sometimes stamped on the rim itself. This is critical for calculating spoke length
* **Spoke Count:** Note the number of spokes your wheel uses. This number has to match your new hub.
2. **Confirm your Spoke Length** This is also where you would want to confirm your correct spoke length. It’s possible you will be able to reuse your old spokes, but it is vital to confirm that they are the correct length. Use a spoke length calculator app or a website to calculate the correct spoke length using the dimensions of the old or new hub (and the ERD of the rim), and your existing spoke lacing pattern.

Step 3: Disassembling the Wheel

1. **Remove Spokes:**
* Starting at the valve hole (or any convenient point), carefully loosen all the spoke nipples with your spoke wrench. Work your way around the wheel, giving each nipple a few turns at a time. If the nipples are very tight and won’t turn easily, apply a drop of penetrating oil to each one and let them sit for a few minutes.
* If using a nipple driver, this will be faster than using a spoke wrench for this step. If you are unfamiliar with either, find some resources online. Improper use of these tools can damage your spokes, nipples, or rim. Be very gentle and do not apply excessive pressure.
* Once the spokes are loosened, you can completely unscrew the nipples and remove the spokes from the rim and the hub. If they are extremely tight, it may be easier to use a spoke holder or third hand tool.
* Keep the spokes in the order that you remove them. You can use a cardboard box with holes to keep the order, or use masking tape and attach each spoke to a piece of cardboard in the order you remove them. Pay careful attention to the lacing pattern as you take the spokes out. Use a picture of the old hub for reference.
2. **Remove Old Hub:** Once all spokes are out, you will be left with just the old hub, which you can now set aside.

Step 4: Preparing the New Hub

1. **Inspect New Hub:** Before you start reassembling, thoroughly inspect your new hub. Check for any defects or damage. Spin the axle to make sure the bearings are running smoothly.
2. **Install brake rotors or cassettes** If required, install them on the hub following the manufacturer’s instructions for torque and installation.
3. **Apply Grease:** Apply a small amount of grease to the spoke threads (if the spokes are not already pre-greased.)

Step 5: Relacing the Wheel

1. **Start with a Reference Spoke:** Find the first spoke you removed (often the spoke at the valve hole) and the nipple that belongs to that spoke. Insert the spoke into the corresponding hole on the new hub and loosely screw the nipple onto the spoke in the rim. You may need to reference the pictures you took to remember exactly how the spokes were laced in your wheel.
2. **Lace Spokes Gradually:** Following your reference pictures, or the spoke patterns you’ve researched online, begin to insert and loosely connect the remaining spokes, working your way around the wheel. Try to insert the spokes one by one, starting with spokes on the same side of the flange, so you get a feel for the pattern. It is extremely important to get the spoke lacing correct, so you may need to undo and try again several times at the beginning. The picture that you took earlier will be invaluable.
3. **Initial Tension:** Once all the spokes are inserted, gently tighten all the nipples a few turns each until all of them are just snug (you should not be able to easily turn the spoke nipple, but they should not be excessively tight). At this point, the wheel will feel very loose. At this point, your spokes will all be in their correct position and you are ready to begin tensioning the spokes.

Step 6: Truing and Tensioning

1. **Mount Wheel on Truing Stand (Optional but Recommended):** If you have a truing stand, mount your wheel on it. This will make it much easier to identify and correct any wobbles.
2. **Initial Tension:** Using your spoke wrench, start increasing the tension in each spoke nipple by turning the nipple a small amount. Work your way around the wheel, applying tension evenly to all the spokes. Keep turning each nipple 1/4 to 1/2 turn at a time, slowly bringing the wheel into shape. Be patient; this is a process, and this is where having the correct tool can make this much easier.
3. **Lateral Truing:** Once all the spokes are tensioned to about the same degree, begin checking for lateral trueness (side-to-side wobbles). Identify where the rim moves more to one side or the other, and tighten the spoke nipples opposite to this movement to correct for it. If the rim moves towards the left, tighten spokes on the right, and vice versa. You must be patient and make small adjustments to the spokes, and then test the trueness again. When you are tightening the spokes, also be very gentle. It is easy to over-tighten spokes at this stage.
4. **Vertical Truing:** Once you are happy with the lateral trueness, check for vertical trueness (up-and-down hops). Identify any areas where the rim moves up and down, and then tighten the nipples in the region with a hop (loosen them in a region that is too low). Again, be very gentle and do not make too many adjustments at once. Check the vertical trueness after every small adjustment.
5. **Spoke Tension:** Once you’ve trued the wheel, check the tension in the spokes. This is where a spoke tension meter becomes invaluable. All spokes on a properly built wheel should have approximately the same tension, within a range specified by the spoke or rim manufacturer. If your wheel is not properly tensioned, it is much more likely to have problems later, such as broken spokes, wobbles, and rim cracks.
* **No Tension Meter Option:** If you do not have a tension meter, you can use the “plucking” method. Pluck each spoke like a guitar string. The tone should be relatively uniform around the wheel. If some spokes feel very loose or sound significantly lower than others, you need to tighten them more. If some are extremely tight, you may need to loosen them. This method is far less accurate than using a tool, but it is better than simply guessing the tension of the spokes.
6. **Stress Relieving:** Once your wheel is trued and tensioned, you can apply pressure to it with your hands to gently stress-relieve the spokes and nipples. Then recheck the trueness. Repeat this process several times.
7. **Final Checks:** Do one final check for both lateral and vertical trueness. If needed, make any minor adjustments. A properly built wheel should not have any significant hops or wobbles. If your wheel does not have good trueness after several tries, consider going through the steps again, and review your work and be sure you’re following correct lacing and spoke tensioning practices.

Step 7: Reassembly

1. **Install Tire and Tube:** Once you’re satisfied with the wheel, remount the tire and tube. Inflate the tire to the recommended pressure.
2. **Mount Wheel Back on Bike:** Mount the wheel back onto your bike. Reattach and secure any thru-axle or quick-release mechanisms.
3. **Test Ride:** Before heading out on a major ride, take a short test ride to ensure that everything is working correctly. Check for any rubbing of the wheel on the frame or fork. Ensure that the wheel runs smoothly and that there are no strange noises or behaviors from the wheel.

Final Thoughts

Replacing a bike hub is an advanced bike repair task, but it’s definitely achievable with patience, the right tools, and a methodical approach. If you’re not confident in your abilities, it’s always a good idea to seek help from a professional bike mechanic. However, if you follow these steps carefully and do your research, you can successfully replace your bike hub and keep your wheels rolling smoothly. Remember to always consult your bike and hub manufacturer’s documentation for specific torque specifications or instructions. Happy wrenching!