Building Your Own Electric Bike: A Step-By-Step Guide

Building an electric bike is a challenging project, but it can be done for under $100. You will need to source most of your materials for free, and have strong problem-solving skills and substantial knowledge of machining tools. The first step is to install a motor, either beneath your pedals or in the front or rear wheel. You will then need to set up the chain, ensuring that the rear derailleur is in the right position to ride.

Installing a motor beneath your pedals (in your bike's bottom bracket)

Building an electric bike can be a challenging project, but it is possible to do it for under $100. You will need to have good problem-solving skills and substantial knowledge of machining tools.

If you want to install a motor beneath your pedals, you will need to follow these steps. First, you will need to break the chain to take it off the bike. Then, set the chain up like normal, going through the rear derailleur and meshing onto the middle sprocket on your rear cassette. Make sure the rear derailleur is in the right position to ride and not bunched up or on the wrong gear. Lay your two chain ends side by side so you can get close to the correct length, then break the chain in that link, ensuring the links you break will mesh.

Next, install the motor beneath your pedals, with the cable on the left side of the bike. Leave it loose for now, but later on, you will run the cable along the bike frame. Make sure you tighten the nuts securely.

Setting up the chain

Firstly, ensure that you have already broken the chain to take it off the bike. This is a standard procedure when setting up a new chain. Now, you will need to set the chain up by feeding it through the rear derailleur and meshing it onto the middle sprocket on your rear cassette. It is important to ensure that the rear derailleur is in the correct position for riding and is not bunched up or on the wrong gear.

Next, lay your two chain ends side by side to get an idea of the correct length. This is often considered the most challenging part of the process. Once you have determined the correct length, you will need to break the chain at that link, ensuring that the links you break will mesh together properly.

After breaking the chain, you will need to run the cable along the bike frame. Make sure to tighten the nuts securely to avoid any loose connections. At this point, you may also want to consider the type of motor you are installing. For example, a mid-drive motor is installed beneath the pedals, in the bike's bottom bracket.

Finally, test the chain to ensure it is set up correctly and safely. Check that the links are meshing together smoothly and that the chain is not too tight or too loose. Adjust as necessary until you achieve the optimal tension and performance. Remember to refer to any specific instructions or guidelines provided by the manufacturer of your electric bike kit for the best results.

Positioning the rear derailleur

Firstly, ensure that the chain is set up correctly, going through the rear derailleur and meshing onto the middle sprocket of the rear cassette. This step is important as it ensures the derailleur is in the correct position for riding and not bunched up or on the wrong gear.

Next, lay your two chain ends side by side to determine the correct length. This is a challenging step as you will need to break the chain at the correct link to ensure a smooth mesh. Once the chain is broken, you can adjust the rear derailleur's position accordingly.

Make sure the rear derailleur is aligned correctly with the rear sprockets. It should be positioned close enough to guide the chain smoothly onto the sprockets but not so close that it rubs against the sprockets or the chain.

Finally, test the gear shifting to ensure the rear derailleur is functioning correctly. Shift through all the gears to confirm that the chain moves smoothly between the sprockets. Make any necessary adjustments to the derailleur's position until you achieve seamless gear shifting.

By following these steps, you can accurately position the rear derailleur, ensuring efficient and safe gear changes on your electric bike.

Running the cable along the bike frame

To run the cable along the bike frame, you'll first need to install the motor with the cable on the left side of the bike. Leave the cable loose for now, but make sure the nuts are tightened securely. Later on, you'll run the cable along the bike frame.

The exact process of running the cable along the bike frame will depend on the type of motor you've installed. If you've installed a mid-drive motor beneath the pedals, the cable will need to run from the left side of the bike, through the bike frame, and into the bottom bracket. If you've installed a rear hub motor, the cable will need to run from the left side of the bike, through the bike frame, and into the rear wheel.

When running the cable, it's important to make sure that it's secure and won't get caught on anything. You may need to use zip ties or cable ties to secure it in place. It's also important to make sure that the cable is long enough to reach the motor without being too long, as excess cable can get caught on things.

Finally, once the cable is in place, you'll need to connect it to the motor. This will usually involve plugging the cable into a port on the motor, but the exact process will depend on the type of motor and cable you're using.

Choosing the right wheel

E-bike tyre sizes typically range from 16 inches to 29 inches, with the most popular sizes being 20 inches, 24 inches, and 26 inches. If you are a shorter rider (under 5'6"), smaller wheels such as 24 inches or 26 inches may be more comfortable and offer better manoeuvrability. Smaller wheels are also ideal for city environments as they are lighter and have a smaller turning radius, making them easier to navigate through crowded streets and tight corners.

On the other hand, larger wheels (26 inches and up) offer higher top speeds, better cushioning from bumps, and easier accessory compatibility. They are more stable on rough terrain but may be less manoeuvrable. When choosing the right tyre size, consider the type of terrain you'll be riding on and your preferences for manoeuvrability versus stability.

Additionally, it's worth noting that each wheel size has its own set of advantages and considerations. Understanding the pros and cons of small wheels versus large wheels is essential to making an informed decision. By taking into account your height, riding style, and the type of terrain you'll be riding on, you can choose the perfect wheel size for your electric bike.

Frequently asked questions