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

Electric bike trailers are a great way to carry more cargo with your e-bike. They are also useful for towing, especially if you want to bring your kids along for the ride. Building your own electric bike trailer can be a fun and budget-friendly project, allowing you to exercise your creativity and build something that meets your specific needs. In this guide, we will explore the different ways you can build your own electric bike trailer, including the materials and tools you will need, as well as some helpful tips to keep in mind.

Design and materials

The design of your electric bike trailer will depend on your specific needs and the power of your e-bike. If you intend to carry heavy cargo or passengers, you will need a sturdy, durable trailer with a strong frame and good load-bearing capacity.

The frame of the trailer is crucial to its strength and durability. You can use a variety of materials for the frame, including wood, metal pipes, aluminium, steel, or even hockey sticks and wheelchair hubs. The type of material you choose will depend on your budget, the desired strength, and the weight of the trailer.

For the trailer's body, you can use a variety of materials, such as plywood, canvas, or even a plastic box. If you opt for a plastic box design, it will serve as the mounting point for the wheels and towbar, keeping the overall weight of the trailer low. However, this may compromise the strength of the trailer. Alternatively, you can build a more durable trailer with a steel frame, like the Surly Ted, which has a load rating of 136kg, far exceeding the average trailer.

The wheels of your trailer are another important consideration. You can use standard bicycle wheels, or, for a more budget-friendly option, you can use pneumatic tires from a mountain bike. The size of the wheels will impact the manoeuvrability of the trailer, so it is recommended to keep the trailer width within the width of your shoulders and a length of no more than 3 feet.

Lastly, the electrical components of your trailer are key to its functionality. You can power your trailer with a combination of solar panels and batteries. Solar panels can be mounted on the roof of the trailer, and a simple boost converter can be used to get the required voltage for the battery. You will also need a gear shift mounted on the handlebars to control the speed and power the motor.

Power sources

Powering your electric bike trailer is a crucial aspect of its design and functionality. Here are some options for power sources and considerations to keep in mind:

Electric Motor and Batteries:

The most common power source for electric bike trailers is a combination of an electric motor and batteries. The motor is typically mounted on the trailer and connected to the trailer's wheel, providing the necessary propulsion. A gear shift mounted on the bicycle's handlebars allows the rider to control the power and speed of the trailer. It is important to ensure that the motor has sufficient traction by having enough weight on the trailer.

Battery Options:

When it comes to batteries, you have a few options. You can use a single large battery or multiple smaller ones. Larger batteries can provide more power and range but may add significant weight to the trailer. Smaller batteries offer the advantage of customising weight distribution for different trips, but they might be more expensive in the long run. Ensure that the batteries are securely mounted, preferably under the trailer, using nylon straps.

Solar Power:

An innovative and environmentally friendly approach to powering your electric bike trailer is through solar energy. You can install solar panels on the roof of the trailer, harnessing sunlight to generate electricity. This method can help offset the extra power required to pull the trailer, especially during camping trips or when riding in direct sunlight. Keep in mind that the efficiency of solar panels can be improved by angling them towards the sun when the bike is stationary.

Charging Considerations:

It is important to consider the charging capabilities of your power source. Standard 12-volt automobile battery chargers or other 12-volt chargers can be used to recharge the batteries of your electric bike trailer. Additionally, solar panels can be utilised to slowly recharge the batteries while riding or during extended stops.

Power Management:

To optimise power usage and prevent overheating, it is crucial to manage the load on the motor. Downshifting or pedalling harder can reduce the motor load, especially when riding up steep hills. Additionally, occasional replacement of motor brushes may be necessary to maintain optimal performance.

Safety and Compatibility:

Always prioritise safety when working with power sources. Ensure that the power setup is compatible with your electric bike and the hitching system. Avoid overloading the motor, and be cautious when using power sources in freezing temperatures, as discharged batteries can be sensitive to extremely low temperatures.

By carefully considering these power source options and guidelines, you can effectively power your electric bike trailer, ensuring both functionality and safety on your journeys.

Construction

Constructing an electric bike trailer can be a fun and rewarding project, and there are various ways to go about it. Here is a step-by-step construction guide with some general tips and suggestions to help you build your own electric bike trailer.

Firstly, you need to decide on the materials and design of your trailer. Some common materials used include wood (such as plywood), metal pipes, aluminium stock, and even hockey sticks or wheelchair parts. You can also opt for a pre-made frame, such as a golf bag caddy or a pre-built trailer frame like the Radical Designs Cyclone, which you can then customise. If you're feeling adventurous, you could follow Bob's example and include a rigid solar panel on gas pistons for charging on the go.

Next is the assembly of the trailer. If you're handy with tools, this process can be relatively straightforward. You'll need to cut and shape your chosen materials to the desired size and shape, ensuring it fits your bike and intended use case. This usually involves a lot of gluing, screwing, and possibly some welding, especially if you're working with metal. It's important to keep the dimensions in mind: the trailer should ideally not be wider than your shoulders or longer than 3 feet for ease of manoeuvring.

Once the basic structure is in place, you can start thinking about adding the electrical components. The electrical setup will depend on your needs and budget. A simple setup might include a standard 12-volt battery, a motor, and a gear shift mounted on the handlebars to control the power and speed. More complex setups could involve multiple batteries, solar panels, and even a boost converter to increase the voltage for faster charging.

Finally, you'll want to test and fine-tune your trailer. This includes testing the electrical connections, ensuring the trailer is securely attached to your bike, and checking the weight distribution. It's important to remember that adding electricity and batteries will increase the overall weight, so you may need to make adjustments to ensure it's not too heavy for your bike.

Some additional tips to keep in mind:

• One large battery is usually cheaper than multiple smaller ones, but smaller batteries give you more flexibility on shorter trips.
• Downshifting completely can help turn off the motor when needed, and remember to avoid overloading the motor to prevent overheating.
• Always use high-quality parts, especially for the motor and gearboxes.
• If you're adding a solar panel, ensure it's secure and adjustable for optimal sun exposure.

Building your own electric bike trailer can be a challenging but rewarding project, and with some creativity and patience, you'll be able to enjoy the fruits of your labour on your next biking adventure.

Safety

When building an electric bike trailer, safety should be a top priority. Here are some detailed safety guidelines and instructions to keep in mind:

Firstly, ensure that the trailer's design includes a flexible element near the hitch, allowing the trailer bar to move independently of the trailer or bike. This feature is crucial for maintaining stability and minimizing stress on the surrounding parts. Some designs incorporate a spring or flexible tube, acting as a shock absorber when carrying heavy loads.

Secondly, pay close attention to the trailer's dimensions. While you can adjust the size to fit your needs, it is recommended to keep the width of the trailer within the width of your shoulders and a maximum length of 3 feet. This prevents maneuvering issues and reduces the risk of the trailer developing a 'snake' motion at higher speeds, which can be dangerous.

Thirdly, invest in high-quality tyres with puncture protection. Low tyre pressure or a flat tyre can be a significant issue with heavy loads, so consider using strong tyres with puncture-proof measures like kevlar and/or slime. Always carry tools, an inner tube, and a plan to remove the wheel if needed.

Additionally, be cautious when selecting batteries for your electric bike trailer. One large battery is generally cheaper and more efficient than multiple smaller ones. However, smaller batteries offer the advantage of customising weight distribution for different trips. Always use nylon straps to secure batteries, and avoid leaving discharged batteries in freezing temperatures.

Finally, always follow basic safety guidelines when riding with an electric bike trailer. Wear a helmet, obey traffic rules, and ensure your trailer has visibility features like bright colours and a flag. Regularly inspect your trailer for any wear and tear, and maintain it properly to prevent malfunctions.

By diligently following these safety measures, you can confidently build and use your electric bike trailer, enjoying the benefits of increased cargo capacity while prioritising your well-being.

Maintenance

Maintaining your electric bike trailer is essential to ensure it runs smoothly and efficiently. Here are some detailed maintenance tips to keep your trailer in top condition:

Firstly, pay attention to any unusual noises, rattles, or squeaks coming from the trailer. If you notice any new or strange sounds, it's a good idea to take the trailer to a reputable dealer or bike shop for inspection. Regular maintenance can help prevent issues, but if you're unsure about servicing your electric trailer yourself, it's best to seek professional help.

Keep your trailer clean, especially the drivetrain. Dirt, mud, and grime can increase wear on components and affect performance. Use a standard wash, but avoid jet washes or fully submerging the trailer in water, as this can damage the electrical components and motor. The motor is sealed, but common sense is needed to prevent water damage.

The drivetrain should also be well-lubricated to ensure smooth gear shifting and prolong component life. Check the belt wear and replace it according to the manufacturer's recommendations. Keep an eye out for loose bolts, spokes, or broken parts, and tighten or replace them as necessary.

The trailer's tyres should be properly inflated, and it is recommended to get sturdy e-bike replacement tyres with good puncture resistance and traction. Regularly check and adjust the brakes, performing a thorough inspection between rides.

Finally, the battery is a critical component. Keep it partially charged and stored in a cool, dry place. Avoid leaving discharged batteries in freezing temperatures. Use nylon straps to secure the battery, and place it on the drive wheel side for better traction.

By following these maintenance tips, you can ensure your electric bike trailer remains in good condition and performs efficiently during your excursions.

Frequently asked questions