Building An Electric Bike Wheel: A Step-By-Step Guide

Electric bikes are a fun and efficient way to move around, and you can easily convert any bike into an electric-assist bike with a basic front wheel hub motor kit. There are many options for front, rear, and mid-drive motors with varying weights and power levels. A low-power front-wheel drive is one of the simplest to install and is compatible with most bikes. You can buy a conversion kit that includes the motor, battery, and all the electronic controls needed to run the system. The process involves removing the original front wheel and installing the new motor with the cable on the left side of the bike. You can also adjust the spoke tension to avoid creaky noises on the first ride.

Choosing a conversion kit

Before choosing a conversion kit, it is important to familiarise yourself with the laws regarding e-bikes in your region. E-bike conversion kits vary widely in terms of power and quality, but all contain essentially the same components: a wheel, controller, battery, and motor. The motor is inside the wheel hub and does the work of starting and stopping the motor. The controller holds the battery, which is what powers the whole system. The battery life depends on factors such as its charge, temperature, how much pedalling you do, terrain, your weight, etc.

When choosing a conversion kit, you should consider your range and journey needs. For example, if you live in a hilly city, you may want something with more top-end power. The kit will need to fit the dimensions of your forks, the width of the rear stays, wheel sizes, and the type of brakes you have. You should also consider where the motor will be located. Front hub motors are typically the easiest to fit, while mid-drive motors are compatible with all brake types but require more effort to install. Hub motors are usually geared for a specific wheel size to ensure they stay within the speed limit set for electric bikes in the territory in which they are sold.

There are a variety of conversion kits available on the market, including the Voilamart kit, the Swytch kit, Bafang’s 48-volt 500-watt front-hub motor conversion kit, and the Ebikeling waterproof e-bike front- or rear-hub conversion kit. The Swytch kit, for example, comes with everything you need to convert your bike, including a battery, charger, pedal sensor, motor wheel, and more. The installation time for the Swytch kit depends on your Power Pack option and your personal skills, but it usually takes between 25 to 45 minutes. The Voilamart kit, on the other hand, does not come with a battery, and you will need to remove the bike's crank to fit the pedal sensor.

Removing the front wheel

To get started on building your electric bike wheel, you'll first need to remove your bike's original front wheel. Here's a detailed, step-by-step guide on how to do this:

Flip your bike upside down, so it's resting on its handlebars. This will give you easy access to the front wheel. Before you start, it's a good idea to check if your front fork has ordinary slotted dropouts. This is important because a front hub motor won't work with a modern high-end thru-axle system.

Now, you're ready to remove the front wheel. If your bike has quick-release levers, open them and then remove the wheel. If your bike has nuts, you'll need to loosen them with a wrench before taking the wheel off. Be careful not to lose any washers during this process! Place the removed wheel to one side, along with any nuts or washers.

At this point, you might want to inspect the brakes and ensure they're in good condition. If there's any damage, it's worth getting them checked or replaced by a professional, as mentioned in the introduction.

With the front wheel removed, you now have the space to install your new electric front wheel hub motor. Remember to follow the manufacturer's instructions for your specific kit, but generally, you'll be connecting the motor, battery, and electronic controls.

Finally, once your new electric front wheel hub motor is installed, you'll want to adjust the spoke tension. This is important to get right, as overly tight spokes can break, and you don't want them too loose either. Adjust the spokes ¼ turn at a time until they're at the desired tension. A good way to test this is by plucking a spoke; if it sings a high C note, it's too tight.

Installing the motor

Firstly, ensure you have a suitable bike for the conversion. Old mountain bikes are usually ideal, but almost any road bike, beach cruiser, or hybrid bike can work too. It is important to check that the front fork of the bike has ordinary slotted dropouts, not a modern high-end thru-axle system, as this is crucial for mounting the motor.

Next, flip your bike upside down and remove the original front wheel. This will involve either a quick release mechanism or unscrewing the nuts holding the wheel in place. With the front wheel removed, you can now install the electric hub motor. Place the motor into the front fork dropouts, ensuring the cable is on the left side of the bike, as per standard configurations. At this stage, you should only loosely attach the motor, leaving the nuts slightly loose, as you will need to adjust the positioning and tension later.

Once the motor is in place, you can start lacing the spokes. This process involves crossing the spokes so that the tensioned spokes transmit torque between the hub motor flange and the rim. The lacing pattern you use will depend on the size and type of your hub motor. Smaller diameter hub motors with large rims can use a double cross lace, while radial or 0-cross lacing is suitable for front wheels without torque transmission requirements. For hub motors with larger flange diameters, a single cross may be sufficient, as it results in a larger angle than a triple cross in a regular hub.

After lacing the spokes, ensure you tighten the nipples securely, working from one side of the bike to avoid confusion. Aim for a balanced tension, as overly tight spokes can break, while loose spokes can cause unwanted noise and movement. As a general guideline, the spokes should not sing a high C note when plucked, and you may need to adjust the tension after the first 50 miles of riding.

Finally, run the cable along the bike frame and securely tighten all nuts and bolts. Your electric bike wheel is now ready for testing and fine-tuning! Remember to refer to the specific instructions provided with your motor kit, and always prioritize your safety when working with electrical components.

Adjusting spoke tension

Firstly, it is important to understand that spoke tension refers to the force exerted on the spokes of a wheel. This tension can be adjusted by tightening or loosening the spokes. The goal is to achieve uniform tension across all the spokes, with a difference of up to 20% between individual spokes being acceptable.

To begin adjusting spoke tension, you will need a few tools. These include a wheel truing stand, a spoke wrench that fits the size of your spokes, and a spoke tension meter. Park Tool's TM-1 is a popular and affordable option for measuring spoke tension.

Before making any adjustments, it is crucial to measure the initial tension of your spokes. Hold the tension meter horizontally, squeeze the handle, and place an individual spoke between the posts. Release the handle and read the measurement on the meter's scale. Repeat this process for all the spokes on one side of the wheel, as tension can vary between the two sides.

Now, you can start adjusting the tension. If your spokes are too loose, tighten them by turning them 1/4 turn counter-clockwise, and then remeasure. It is important not to overtighten the spokes, as this can lead to damage. Aim for a tension that is just below the recommended kilograms force (kgf) for your wheel size.

Additionally, consider using a spoke tension calculator to determine the ideal tension ratio for your wheel setup, especially if you have a rear wheel with a large difference in bracing angles. This will help you fine-tune the tension to avoid premature spoke failure and ensure a long life for your wheels.

Remember, achieving perfect uniformity in spoke tension can be challenging, and it takes practice to become proficient in wheel building. Take your time, don't rush, and always prioritize safety.

Replacing a rim

To replace a rim on an electric bike, you'll first need to remove the wheel. This will either be done via a quick-release mechanism or by unscrewing nuts. Once the wheel is off the bike, you can begin the process of replacing the rim.

First, use a spoke wrench or a flat-head screwdriver to remove the spoke nipples from the old rim. If your bike has rim brakes, be careful not to get any lubricant on the new rim. Next, bring the free spoke up to the new rim, ensuring that the hole for the spoke matches up with the hole in the rim. Attach the spoke nipple and turn it counter-clockwise until only two threads are visible above the nipple.

The trickiest part of the process is placing and keeping the spoke nipple into the new rim. One method is to use a junked spoke: put the threaded end of an old spoke through the desired hole, loosely thread the nipple, pull the nipple into place, and then remove the helper spoke.

Finally, adjust the spoke tension. If the wheel is creaking, tighten each spoke by a quarter turn and test it again. Avoid too much tension, as this can cause spokes, rims, or the motor flange to break.

Frequently asked questions