Electric Bikes

Know how to build an electric bike & build your own.

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Although electric bicycles make it much easier to commute around urban areas and cities, they can also be very expensive but if you know how to build an electric bike then it will be cheap for you. Top brands such as Raleigh Redux IE and Trek’s Super Commuter 8s offer high-quality electric bikes that combine high performance with high quality in a compact package. The price of top-end electric bikes can be expensive, however, at $3,000 to $5,000.

how to build an electric bike

The other end of the scale, the most affordable option is the cheap, imported from Asia electric bikes that are shipped in the US starting at $500. We’ve previously reviewed these super-budget electric bicycles, and the verdict often comes back the same – ebike parts: decent; bike parts: mediocre at best.

Simply put, manufacturers don’t have many options for electric bike motors, controllers, or batteries. They all rely on the same mass-produced, high quality components. To keep these electric bikes as cheap as possible, there must be no compromises. In these cases, the only thing that is left to cut are the components of the bicycle.

These bikes have good frames, but they are not great for bolt-on components. The suspension is nothing more than a spring inside a tube. Seats are harder than park benches, and brake components creak and bend in ways that don’t inspire confidence.

These budget ebikes can be used for short trips or as an alternative mode of transportation. However, they are not suitable for more experienced cyclists who want a better quality bike with electric assist. A better quality bike will be a necessity for anyone who wants to replace their car on many of their trips around the city.

How to build an electric bike

For those who are creative and don’t mind putting in a few hours, it is possible to combine quality components from bicycles with ebike parts to create your own affordable, high-quality ebikes.

There are electric bicycle conversion kits that can be used to convert standard pedal bikes into electric bicycles. They cost a fraction of what retail electric bikes, but offer the same performance. An electric bicycle conversion can often be done for less than a budget ebike. This method has the advantage that you can use a bike that you already own. These bikes will almost always be of higher quality than those used in budget electric bikes. You also have much more room for customization and choosing the exact bicycle to fit you best, or even go with something odd or unique, like a two person tandem bicycle. It was fun to do a DIY conversion of an electric bicycle on a tandem bike.

The majority of electric bicycle conversion kits include all the necessary components, except for the battery. It is the most expensive and important part of an electric bike, so it is nice to have the option to select it separately. Below, we’ll be discussing both the battery and the other components.

How to choose an electric bicycle battery

You will need to know the capacity and voltage of your battery. The voltage of an electric bicycle is typically measured in 12V increments, ranging from 24V up to 72V. Higher voltages will result in a higher ebike’s speed and power. 24V ebikes can only be used for low speeds, flat terrain and light riders. My wife isn’t what you’d call a thrill seeker, so I built her a nice, low power ebike with this 24V battery designed to mount easily on the seat tube of folding bicycles.

If you are looking for more power and speed, the 48V and 36V options are best for you. They can both go up to 28 mph (45 km/hr). This 36V ebike battery is made from Samsung batteries. However, I prefer 48V ebikes for personal rides. I enjoy the extra speed on flats and the extra power when climbing hills. For those who want to build ebikes capable of reaching speeds between 30-45 mph (48-72 kilometers/hr), the 60V and 72V options will be ideal. If you don’t have any motorcycle riding experience, I wouldn’t recommend you go this fast with your first ebike. Keep in mind that the more powerful the battery, the more expensive it will become. You’ll also want a good quality, dual suspension mountain bike for speeds over 30 mph (48 km/hr).

how to build an electric bike

Capacity

Next, choose the battery’s capacity. The capacity of your battery is measured in amp hours and watt hours. This will affect how far you can go. A common starting capacity is 10Ah, but increasing to 20Ah can give you more range. It is uncommon to have more than 20Ah, so it is mostly reserved for cross-country trips and touring ebikes. For a battery capacity of about 3 kWh, my longest XC trip was 500 mi around Florida. I used two 72V 20Ah batteries. For trips around town, however, 10 Ah is sufficient.

If in doubt, I recommend using a larger capacity battery. A higher capacity battery will not only make it less likely that you run out, but also lasts longer and is more efficient because each battery cell doesn’t have as much work. The battery’s capacity will determine how heavy and expensive it is.

Many electric bikes sold in retail stores don’t list the voltage and amp hours of their batteries. Instead, they only list the watt hours. You can compare them by adding the voltage and amp hour together to get the watt hours.

Watt hours = Volts x Amp Hours

A 48V 10Ah battery, for example, is equivalent to 480 Watt hours (Wh). When comparing electric bicycle batteries, the voltage and amp hour are listed rather than watt hours.

You can approximate the range of an electric bicycle by using 25 Wh/mi to determine it. This approximation will show that a 480 Wh battery should be able to carry most people for around 20 miles (32km). Range can be affected by factors like rider weight and terrain. You can also increase your range by pedaling with the motor power.

Battery

Finally, you can choose between two types of electric bike batteries: a frame-mounted battery or a rack/frame-mounted battery. The first (pictured below), bolts to the frame using the holes for water bottle holders. The second mounts in a frame bag or rack. A battery above 60V will require a frame bag to mount. Higher voltage batteries are rarely available in easy-to-mount cases. This 72V battery is the most common high-voltage ebike battery. It requires either a rear rack or a triangle frame bag to mount. Because of their simplicity, most people prefer frame-mounted batteries. Mounting the battery between your knees on the front triangle of a frame will keep the center gravity lower and closer to the bike’s center, which improves handling. Personally, I prefer to use a triangular frame bag in my bicycles, but that’s mostly due to the fact that I am a battery geek and like to make large custom battery packs to fill up any space.

Kits for electric bicycle conversion

Kits for electric bicycle conversion

After you have chosen your bike, you will need an easy-to-use, bolt-on conversion kit for your electric bicycle. The kit includes all the electronics needed (except for the battery). There are also a few accessories like gauges, displays, gauges and fancy brake levers depending on which kit you choose. This specific electric bicycle conversion kit is a good quality, budget kit that I’ve used many times. You can choose from 500W or 1,000W options. It also works with 36V and 48V batteries. This is great for those who want to increase their speed. If you shop around, you’ll find other electric bicycle conversion kits with similar or identical looking motors. Even though they may be from different manufacturers, the majority of these motors use the same parts that are made in China. The market for ebike conversion parts is very limited. It has been a simple mindset that “if it works it will keep producing it.”

There is also a second type of electric bicycle conversion kit that uses a mid-drive motor to replace your bottom bracket and provide power directly to the crank. These mid-drive kits have the advantage of allowing you to run your electric assist through all your gears, instead of just one like with hub motors. Multiple electric-powered gears can make it easier to climb steep hills. These kits can be more difficult to install and fit a smaller percentage of stock bikes. They are also 3-5x more costly, so I wouldn’t recommend them for your first conversion.

Although most hub-motor-based electric bicycle conversion kits look very similar, there are some things you need to know. These include the power level, which wheel has the motor and whether the kit is the right size for your bike.

Power Option

There are many power options available for some kits, which are measured in watts. Power levels exceeding 750 watts will not have an impact on speed, except if you are traveling at speeds of 20-25 mph (32-40 km/hr). For flat ground, 250-500 W is plenty of power to get most people up to speed, albeit with slower acceleration. A 250 W ebike might be the right choice for you if you’re light and can tolerate a slower acceleration to reach cruising speeds. You’ll appreciate an increase in power to 750 W if you live in a hilly region. Or even 1,000 W if you live in extremely hilly regions. Higher power levels will be more beneficial for larger riders, even on flat ground.

Personally, I find that a 48V and 750-1,000 W system is the perfect amount for most people. This combination gives you a little more power and speed than most people will need. You won’t have to keep the throttle at 100%. Imagine driving a car this way.

The final decision is whether you want a rear or front motor. For smaller installations, a front motor is more suitable. It usually comes in the 250-350W range. A front motor makes it easier to change the tire, while a rear motor can be more frustrating. Many front forks on bicycles are not designed to handle large motors. Rear wheel drive is the best choice for motors with more than 500 W (for aluminum frames) or 750W (for steel frames). Due to the lighter weight of the front wheel, motors mounted in the rear can cause burnouts. This is up to the rider. You could also get fancy and have both the front and rear motors to make an all-wheel drive ebike. Swooon

Installation of the electric bike conversion kit

After you have chosen your kit, it is very simple to install, especially if this is the first time you have ever changed a tire on a bicycle. Simply remove the old wheel from your bicycle and transfer the inner tube and tire to the electric hub motor. Next, attach the speed controller (the brain for the ebike), to the frame. Finally, add the throttle to your handlebars. To make it easy to connect, all kits should include compatible plugs.

Connecting the battery and speed controller can be the most difficult part of the process. They might not have the same connectors if they came from different sellers. You will only need to replace the wire connectors on either one or both of these components. This will not be a problem if you are competent with a soldering gun. You can simply remove the old connector and attach a new one. You can find electrical connectors with pre-connected wires that make this job even easier. This will likely be the only soldering required for the project. You should be careful not touch the battery wires while they are temporarily exposed. This could cause a short circuit. You may have experienced a short circuit with a 9V battery when you touched the terminals to an object metal. Now imagine that spark, but bigger. This is how I have seen electrical connectors made of gold literally evaporate. You can be there one minute and gone the next. Poof.

Don’t worry! As long as the wires are kept separate while you replace connectors, this shouldn’t happen.

Your ebike is ready to go once you have connected the speed controller and your battery. You can then test drive your ebike by simply ensuring that all wires are removed and securely velcroed or zip-tied to the frame. Oh, and don’t forget a helmet – safety first!

Save money by doing it yourself

It’s possible to make a DIY electric bike that is as efficient or more effective than an expensive brand. All you need is a kit and some time in your garage. The Trek SuperCommuter 8s reviewed by Electrek is a beautiful electric bike, but costs $5,000. This conversion kit and the 36V battery can be used to make an ebike that is very similar in speed. You can get a slightly more powerful motor and a larger battery for about $450. This price does not include the cost of the donor bike. It doesn’t come with all the Trek features like an integrated headlight, internal cables routing and a bottom bracket motor. But you can still make your own electric bike from the $4,500 that you have saved.

Remember that you won’t receive the same support and warranty if you make your own electric bike. The price tag for an electric bicycle can be a lot more than the actual bike. For those who are brave enough to go it alone, there are many options for building your own electric bike and saving a lot of money.

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