How I Built My First Electric Bike

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How I Built My First Electric Bike

One day I became fed up with all of my excuses for driving to work every day. During the summer I would ride my bike, but it would come in waves without any consistency. There is one huge hill climb to get to my work that is quite daunting, and is the main reason why most people take a vehicle, especially when you are running late. One day I said, screw it — I am going to put together an electric bike.

I recently read an article about what the average person can do to prevent climate change and a green commute was at the top of the list. Besides everyone needs a project to work on during the winter or rainy months.

But how would I build a bike? What motor would I use? What batteries should I choose? All these questions and more can help you build your own bike.

Getting Started

Photo by Scott D. W. Smith
Photo by Scott D. W. Smith

If you type “diy electric bike” in your favorite search engine, you will find a barrage of information from electric drill bikes to the top 10 most expensive electric bikes. The information can be daunting and lead you in many directions, only to cause confusion with so many choices.

My goal was simple: build an electric bike that everyone can replicate with minimal cost, without electrical know-how, but be powerful and reliable at the same time. Another major goal was to decrease complexity over other builds, which in turn would make maintenance easier over time.

My Parts List

Choosing a Motor

In my opinion, the first item you should decide on is the electric motor. Traditionally the hub motor has been the most popular choice for electric bikes. With the hub motor you have two choices, geared hub motors and direct drive motors. Each type has its own pros and cons which can be viewed here:

A relative newcomer to the scene is what is called a mid-drive electric motor. The mid-drive electric motor is not installed in your front or rear wheel hub, but attached to your front drive system. The main advantage to this system is the ability to use your own bike’s rear derailleur to change gears. The motor has its optimum rpm speed which you can sense when riding the bike. When the chain spins really fast, but your speed doesn’t increase, you simply change to a lower gear in the rear to get the perfect combination.

I chose to use the mid-drive Bafang BBS02 motor kit. The downside to this design and kit is the fact that the pedal-assist mode can “crunch” your rear chain rings in the back when shifting. You typically have to pedal your bike to get the rear derailleur to change chain rings. The controller then detects that you are peddling your bike and then spins the front ring. You then hear a “crunch” from the back chain sprocket as it is shifting gears. There are a couple of ways around this design flaw:

  1. The manufacturer needs to detect not just the fact that you are pedaling, but also applying a certain amount of force at the same time before turning the front chain ring.
  2. You can turn the pedal-assist mode off while changing gears, or turn pedal-assist mode off entirely.
  3. Some people just tap the breaks, which kills the motor. Within this short amount of time you can shift several gears
  4. Buy or use a Shimano Nexus 8 speed rear hub. This allows you to change your rear gears without pedaling.

For me, the benefits of this design outweighed the negatives. In the following videos, I demonstrate how the bike performs with the Bafang BBS02 mid-drive motor kit. I would like to make two notes: I am aware that I need lube for my chain (taken care of), and yes a bigger hill is needed. Enjoy!

(Most) Any Bike Will Do

The beauty of this electric bike is that you can install the kit on pretty much any existing bike with a 68mm bottom bracket shell width. Choosing the bike to convert into your new electric bike is really fun. If you have an existing bike to use, you can save a bit of money, which is what I did. You can also find a good bike at your local bike shop or even Craigslist. Here are some things to look for when choosing components for your next e-bike:

  • smaller wheels generally means stronger wheels
  • more spokes in your wheels means stronger wheels
  • fat tires provide smoother ride when your bike is loaded down with weight
  • front disc brakes are recommended for stopping on steep hills
  • look for bikes that contain eyelets for rack attachments
  • the more weight your rear rack can support the better for supporting batteries and other gear
  • extra wide handle bars are good for mounting all of your e-bike accessory and lights
  • If you buy a used or new bike, and you are going to use a mid-drive motor kit, don’t invest your money into the front derailleur or one with a nice double or triple crank set up front. You will be removing these components, if using the mid-drive kit. So, look for single speed bikes or fixies. The problem with fixie bikes is that they are generally a minimalist bike without eyelets for rack attachments etc.

After choosing your desired bike, the first step is to remove your chain, front crank set, and bottom bracket. Some chains are connected with a quick link which can easily be pulled apart. Other chains may require a chain tool to remove a link from the chain to get it separated.

The next step is to remove your crank set. This usually involves using a hex tool to remove your crank arms, and then using a crank puller tool to pull the crank assembly away from your bottom bracket. Once you have the crank set removed from your bike you will need to remove your bottom bracket. The bottom bracket will generally unscrew using a special tool that matches your specific bottom bracket as there are several different models. Now you are down to the hole in the bottom of the frame. This is a good time to clean this part of your bike before you attach the new mid-drive motor assembly.

Close-up of Bafang BBS02 motor installation on bike
Close-up of Bafang BBS02 motor installation on bike

Unless your number one love in life is bikes, you probably don’t have every bike tool needed for this project. It is a really good idea to make friends with a bike mechanic at your local bike shop. Tell them what you are building and see if they have any good ideas. I did remove my crank set myself, but did not have the bottom bracket tools. I took my bike to the bike shop to have them remove my bottom bracket and install the mid-drive motor kit. I could have purchased the tools to do it myself, but he was able to do it for me in as little as five minutes. They didn’t charge me because it was so quick — and because they would be making money on all of my bike accessory purchases (which is a really good business model and great customer support).

The mid-drive kit slides through your bottom bracket and is screwed down tight on the other side with 2 hex screws tightened to 35-40nm of force. This is quite a bit of force and is typically how much force one person can generate with a hand tool using all of their might. One thing to note is that after two weeks of riding my bike, I had to re-tighten the mid-drive hex screws. I also had to re-tighten the screws holding my rear rack to the bike. Re-examining your bike for loose components is necessary for any bike, but even more so for electric bikes because the forces applied to them tend to be higher over time. Once you have the mid-drive kit installed on your bottom bracket the rest is pretty easy. Simply route the cables coming out of the motor to the designated locations on your bike.

Stabilizing and Securing the Battery Box

The bike that I chose already had a setup for a rear rack. In the past this bike has been used for bicycle touring and I was confident in the rack’s ability to hold weight. I simply installed my rear rack and set the battery box on top of the rack. This was not a very good idea because the battery box was sliding all over the place.

I decided to make my own cargo-style rear rack with a wooden platform. To do this I took a 1″x 4″ board of “strong” wood, maple, I believe, and cut it to the desired length. I then determined the exact location for this platform on my rack and used perforated metal hanging strap that you can buy at any home improvement store to attach the bottom side of the platform to the rack. I used short wood screws and cut the strap to small lengths and screwed the rack and platform tight in several locations.

Battery Box holder, the top plate supports the weight, while the rectangle keeps the battery box in position
Battery-box holder: the top plate supports the weight, while the rectangle keeps the battery box in position

This platform now solved the weight and stability issue of the battery box, but the box could still slide side to side and fall off pretty easily. I measured the battery box and determined the length of small pieces of 1″x 1″ wood strips that would wrap around the battery box and be screwed together forming a rectangle. I then determined the desired position of the battery box on the platform and screwed down this wooden rectangle onto the platform using short 1/2″ brackets found at the hardware store. The battery box then fit right into the rectangle like a glove. All that is left is to use some Titan Straps to cinch down the battery box to the rack and she shall not move!

Side view of custom wood top mounting plate attached to rack
Side view of custom wood top mounting plate attached to rack

Engineering a Battery Pack

When building an electric bike, typically you want to keep your weight as low as possible. However, engineering a battery pack to fit between the frame triangle takes a bit of time, money and expertise. You can buy the em3ev battery triangle packs from Paul in Hong Kong, which offer high power and capacity. The ping battery is another option, however both of these batteries suppliers have to ship to the USA for around $100. It was really a toss-up between these two builders in the end.

I ran across a forum on about using prismatic LifeP04 batteries for solar power storage ( The second comment by turbo1859 caught my eye. I paid close attention to how he has previously constructed his battery packs using the prismatic cells. I ultimately chose these batteries for the simplicity of balancing the cells, and the ability to remove or replace cells in the future without having to rip apart the battery pack and remove the cells that are soldered together. I could simply replace a cell without having to solder a new one in series or parallel within the pack. The problem with these batteries is they are not lightweight. I believe all 4 packs weigh about 26 pounds.

The Need for Battery Management Systems (BMS)

Almost any time you build a lithium battery pack you need a BMS. A BMS requires a wire to connect to each cell to balance the voltage or state of charge across the battery pack. Each one of these wires connects to the BMS circuit board to provide overcharge protection, discharge protection, overheat monitoring, short-circuit protection, and balancing functions, etc. During high discharge and charge sequences, the cell voltage and capacity can differ between cells, thus the need for a BMS.

Using the balancing cells, a smart charger, and the motor cutoff thresholds, I would be able to get away with not having to use a BMS.

This modular functionality in my opinion is very important. And the fact that’s products are designed and assembled in the USA is important to me. So I made my decision to go with these batteries. Of course I would have to buy four 12-volt packs and 16 LED balancing modules. I would also have to buy a 52-volt smart charger to charge all of the batteries when I wire them in series. A 52-volt charger would prevent me from having to babysit the batteries during the charging process, which was really important to me. The smart charger automatically cuts power when the batteries are full, preventing overcharging issues.

Batteries connected in series for the first time with battery charger hooked up to positive and negative terminals.
Batteries connected in series for the first time with battery charger hooked up to positive and negative terminals.

Once I received my batteries I tested each cell and each pack of 4 cells for voltage differences from the manufacturer. I then connected the four packs in series to quickly test the smart charger. Once I verified that the smart charger was working properly, I then started to install the LED balancer modules on each of the 16 cells. Each of these balance modules installed without any issues. Each 12-volt four-pack then needed to be connected in series to each other to make the 48-volt pack required to run the motor. The extra connector bars that I ordered didn’t quite reach from one battery to the other, so I flattened them down with a hammer to extend their length. The length was perfect and it also allowed me to put a small piece of cardboard between the batteries for shock protection.

12 volt battery pack with led balancer modules
12-volt battery pack with LED balancer modules

After the batteries were connected in series I then wrapped the battery pack with duct tape to secure them together. After adding sufficient packing material to the empty battery box, I slid the battery pack into the box with a nice snug fit. I decided to add a 30 amp inline fuse to the positive battery terminal of the battery pack. You could also add the fuse to the negative terminal, but I believe it is standard to be installed on the positive terminal.

Battery pack stuffed into battery box with foam packing for snug tight fit
Battery pack stuffed into battery box with foam packing for snug tight fit

I then drilled a 3/4″ hole in the battery box to mount the keyed switch, followed by connecting the positive lead cables to the appropriate terminals on the switch assembly as indicated on the package material. With each wire connection, I made sure to use heat-shrink tubing at each cable termination. I then measured, cut, and installed the positive and negative cables needed to extend from the battery box to the XT90 connector and cable that connects to the motor. The motor came with an extra female end XT90 connector which I soldered onto the negative and positive cables from the battery box. I also use this female XT90 connector when charging the battery pack using the smart charger, since it has alligator clips and connects quite easily.

30 amp inline fuse holder and key switch connections
30 amp inline fuse holder and key switch connections
View of battery box, keyed switch for a bit of added security.
View of battery box, keyed switch for a bit of added security.

Alternative: Pannier Carriers

My updated design requires the use of pannier bags that attach on each side of the rack. I would simply put my batteries into each pannier equally to distribute the weight.

The original battery holder design used a wooden battery box (above). However this design posed issues with weight high up on the back side of the bike. When parking the bike, the kickstand was very unstable. The bike would tend to topple over if someone accidentally touched of the bike. I was also nervous when parking the bike at the grocery store or some other stop in town. So I decided to remove the battery box and install pannier bags. This new design is simple because it keeps the weight down low making the bike more stable. In addition, the bags could be used to carry extra gear and items around town. The only inconveniences are the fact that you have to run a series wire from one bag to another to connect each 24V battery pack. As well as any 48V connection would have to span two packs.

Each 24V battery pack was then duct taped together and put in a separate pannier bag. Again, I added a 30 amp inline fuse to the positive battery terminal of the battery pack. You could also add the fuse to the negative terminal, but I believe it is standard to be installed on the positive terminal.

As before, I made sure to use heat-shrink tubing at each cable termination, and used the XT90 connector.


Creating a Custom Kickstand

The only thing left was to add a double kickstand and some lights. The kickstand is really important for a bike of this weight. In my case, the kickstand makes it easier to unload and load my young son from the bike trailer I pull behind me. I simply flip down the kickstand and then the bike is stable.

Coolest mod to tire lever — double kickstand top mounting plate
Coolest mod to tire lever — double kickstand top mounting plate

The problem with my bike was that there was not a top mounting plate for a kickstand. There was, however, a small opening in my frame for the bolt to extend through. You have got to check out the tire lever that I modified to become the top mounting plate for the kickstand. It works really well, and I have not had to re-tighten or mess with it yet! Simply cut a tire lever with a hack saw to match the width of your frame. And then carve a similar curve with a knife or saw on the other side. Tire levers have this circular indention on one side, and that is exactly where I drilled my hole to fit the kickstand bolt. And voila! The kickstand works great!

Mounting a Taillight, Headlight, and Horn

I previously used standard battery type rear and front lights. However I have grown tired of constantly changing their batteries and or charging the batteries. I wanted a system where I could run the lights from the main battery pack. Unfortunately, most bike shops don’t offer these lights so you have to search specialty scooter stores or other e-bike online sites. Once I found the 48V wired lights it was a matter of installing them on the bike. Most rear pannier racks have a mounting bracket for a tail light.

Unfortunately for me, the holes did not align up with my rear light. I simply drilled a hole through the metal at the exact location for the rear light mounting bracket.


The front light/horn did not come with a bike handle bar attachment. However, I had several laying around from all of my previous bike product purchases. Otherwise you can visit your bike shop to see if they have one lying around the back stock rooms for free. A simple ¼” bolt and nut is used to connect the handle bar attachment and mounting bracket for the light/horn unit.

First and foremost, make sure that when wiring the lights and front switch you measure and connect your wires without them connected to the batteries. (This will prevent damaging your switch or newly purchased lights.) My main wiring goal was to power the head lights, the front horn, and tail lights all with one set of wires from the batteries.

I used some simple speaker wire I had lying around from a previous project. This wire is great because it has 2 wires with a protective sheath on the outside. I stripped the wire 2 feet from the end and crimped a ring connector on each end. I then measured and cut the wire to extend from the battery packs all the way to the front handlebars where the switch would attach. The switch unit has screws that allow you to see how each individual accessory switch is wired. I connected my positive wire to each of the 3 wires that create the positive circuit for the front light, front horn, and rear lights. The negative wire was then connected to complete the 3 switch circuits. An additional set of wires was then traced back down the frame to the rear light. The front light wire set contains 3 wires enabling you to connect two hot wires and one neutral. Only several inches of wire is needed to extend these wires to your wiring harness installed near the front headset of the bike.

Small lightweight crimp connectors were used to connect the wires. The positive and negative wires from the battery were soldered to provide extra strength. All wires were then heat shrinked and wrapped with electrical wire to create the wiring harness.


Driven to Ride

In my experience so far, I have had to charge my battery pack once a week. Even with pulling my child behind me to school and back everyday. However, I only ride about 7 miles round trip each day, but there is one major hill that drains the battery juice.

First working version of e-bike, with built-in mounting system on rear rack.
First working version of e-bike, with built-in mounting system on rear rack.

Now that I have built this bike, I think that I overdid the battery pack a bit with the weight, but the increased capacity, once a week charge requirement, and other pros have justified my positive opinion of this design. The bike literally helped transform my life. I no longer drive to work everyday, I ride my bike instead. Even during the cold winter months, I bundle up my 2-year-old son and transport him to school. I’m riding 90% of the time, which has drastically cut the carbon emissions I was generating.


Here are some websites you can use to gather information that you will need to start building your next e-bike:

Home Page

Battery and Kit Options

Other websites of interest:

Bafang BBS02, 750W mid-drive electric bike motor Kit Review

19 thoughts on “How I Built My First Electric Bike

  1. Richard Harris says:

    In the UK your limited to 250 watts and 15 MPH. Your bike has to show the motor wattage and battery voltage on the frame and only operate whilst pedalling. It must weight less than 40 Kg

    1. Parker Jardine says:

      Wow this is really good information. To be honest I am not sure that here in the USA we have these laws. ??Anyone? I think it might still be the wild west.

      1. jgreencyclist says:

        Since when do you care about breaking a few stinkin’ laws?

        1. Richard Harris says:

          Only when a cop stops you!

      2. Richard Harris says:

        Quite likely. We are bound by European regulations. I have seen Youtube viseos of people in Velomobiles being pulled over by cops in USA though.

  2. Mike Saccoccia says:

    This article didn’t cover my biggest question: what did it cost?

    1. Parker Jardine says:

      The Motor kit cost $550 dollars. The batteries cost $450 dollars. The battery charger cost about 100 dollars. So you are looking at about $1k for an electric bike modification with this design.

        1. Parker Jardine says:

          Very cool design. I like the trailer idea with the weight down low. Very stable. However, not sure if I like the idea of it pushing my bike from behind. Also not sure how good it would do on steep climbs. ?? In the flats it looks like it would work pretty good. Now if I could use the trailer idea to hold my batteries down low it might be the best of both designs. :)

  3. TJP says:

    I love hearing about people who have made the switch from driving to riding a bicycle. It is the best thing you can do to improve the World!

    1. Mark Wallace says:

      Same here! I used How To Build Electric Bike (click) to build my own electric bike and I am very impressed! It is remarkably thorough, detailing exactly how to build your own 50mph electric bike step by step. There are illustrations on nearly every page to help you along the way, which is great for those tricky wiring parts! All in all, this is a very comprehensive and well-written guide and I would recommend it to anyone looking to build their own fast electric bike. Worked great for me and I saved a ton of money!

  4. Barbara Hohensee says:

    I like this motor solution. But the battery is kind of big, heavy and expensive. Look at Aliexpress, if you want to change the battery. There have battteries for ebike’s called Frog battery, mounted under the sadel without the need of a rear rack. Less expensive as well, about 250 – 300 USD

    1. Parker Jardine says:

      Yes the battery is big and heavy and expensive. All of the above. I am working on a different battery placement on my bike instead of on top of the rear rack. However, this design was quick and simple to install for the first time. I still like the batteries though, they have some serious capacity to them, and the modular design in the long run will be good for maintenance. Will have to check out the frog battery now. Thanks for the info.

  5. jeff ward says:

    Oh, man! I know that hill up to FLC! I can’t blame you for using an electric bike to get up that thing – it beats hitchhiking!

  6. Blair Nisley says:

    Looks like you have a good setup there. I’m also running the 750w bbs02, great motor! Only im running it at 54v (1100w) on six 18v 5ah dewalt li-ion batteries. Not finished though.

  7. Yosef says:

    Great build, bought the motor, and am getting the batteries/charger – and I noticed that I could not find the model of the charger. Help appreciated – CH-LF48V6-TSL by chance?

  8. Sylvain de Crom says:

    First of all, thanks for the great article.
    2ndly, can you share where you got the 48v lights, I have trouble finding anything usefull on Amamzon in the 48v bike light area :)

    1. Parker Jardine says:

      Here is the light that I used in this design:
      However, I would not buy this light/horn kit again. Constant vibrations over the last year of riding the bike caused this light to break at the very week plastic piece that supports the light. If I were to buy it again, I would try to add some support for the plastic mounting piece. Also the light output was not very good. The horn was fun though! Cheers!

  9. Mark Wallace says:

    I used How To Build Electric Bike (click) to build my own electric bike and I am very impressed! It is remarkably thorough, detailing exactly how to build your own 50mph electric bike step by step. There are illustrations on nearly every page to help you along the way, which is great for those tricky wiring parts! All in all, this is a very comprehensive and well-written guide and I would recommend it to anyone looking to build their own fast electric bike. Worked great for me and I saved a ton of money!

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Manager of Systems Administration in the Information Technology Higher Education space. I enjoy biking, climbing, hockey, camping, mountaineering, hunting, paragliding, and just being outdoors. You can read my Make Magazine project articles about a diy solar panel and solar systems design in volumes 12 and 14.

View more articles by Parker Jardine


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