My E-Bike adventure

Converting a Bike to an E-Bike

Inspiration

During year 12 I decided to start cycling to school. The reason was, that taking the bus to school took way longer than cycling. The problem was that at the end of my daily journey there was a steep hill that would cause me to sweat. The solution that came to mind was buying an e-bike. After some quick research I realised that purchasing one would be expensive. During Christmas I managed to collect some money from working at Sainsburys but not enough to buy an e-bike. This is why I decided to build one from scratch.

Planning ahead

In order to choose the components I had to do some research to make sure that they were compatible. Choosing a battery that outputs a higher voltage than the motor's input would kill the motor. Then I thought about the range I would like the bike to have so I could calculate the capacity of the battery. Finally I had to find a bike so I could install the components.

Considering my options.

There are several ways to convert a bike to an E-Bike.

No.1) Using a Mid Drive Motor

A Mid Drive Motor would replace the crankset on the bike. The advantage of this component is that it assists you when you cycle. The more you cycle the more it assists. This could be useful to someone If he had to cycle a long distance that would be mostly flat. When going up a hill you would still need to cycle hard due to the lack of chainrings.

No.2) Using a Front Wheel Electric Bicycle Bike Motor

Using a Front Wheel Motor is the easiest and cheapest way to convert a bike. You don't have to worry about the chain or mess with any of the gears. One of the biggest disadvantages is that you have to be careful when steering due to countersteering. Steering too quickly while increasing the motor's output would cause the bike to fall down.

No. 3 Using Rear Wheel Electric Bicycle Bike Motor

I found that using a Rear Wheel Motor is the best option since most of the weight of the individual riding the bike is mainly on the bike wheel (That’s why you can do a wheelie pretty easily). That means that the wheel is going to have a bigger normal force and therefore the efficiency of the wheel will be higher. Furthermore going uphill the motor would be more useful since its controlled by a Thumb Throttle meaning I could go up the hill without any effort.

Buying the parts

Rear Wheel Conversion Kit

After some research I found this Conversion Kit that includes all the components. Having all the components included made it very easy since I didn't have to worry about the compatibility of the individual parts.

Afterwards I would have to find a battery that has enough “juice” to give me enough range.

Calculations

To be fair that doesn't sound like a lot. But you have to remember that the thumb throttle is a potentiometer that controls the output of the motor. That means that the motor can run for 37 minutes if it runs at a maximum of 1000 watts. If we use 500 watts the motor will be able to run for double the amount of time and if you are going downhill you don't need to use the motor.

Battery

Using the above calculations I went looking for a battery of 1000W and 48V. Finally I found a battery that I was happy with.

The Bike

Last but not least I had to purchase a bike since I didn’t have one to install the kit and I didn’t want to install it on my main bike. Buying a bike wasn’t easy. I was looking for a bike of good quality with a really cheap price tag. After a bit of looking around I was able to find one on Argos. Please do note that the brakes are not hydraulic but simple V-brakes this is Important for the future.

But enough with the boring calculations in the words of Henry Petroski

“Science is about knowing, engineering is about doing.”

Installing the components

After everything arrived I got to work. First I had to assemble the bike and after that connect all the components together. I found that connecting the controller with all the components was the most challenging part, thankfully every component had a user manual with very good electrical diagrams and it did make it easier despite the fact that all the manuals were written in chinese. I decided to connect all the parts together before installing them on the bike. In the video below I was testing that all the components worked.

I apologise for the quality

I was very excited and happy that everything worked at the very first time since any engineer knows that for something to work the first time is pretty rare.

After that I would have to put everything on the bike so I would be able to ride it. I started with the battery and the controller since they would define where the rest of the wires would go. Quickly I realised that there wasn't enough space for the controller so I had to buy a bicycle rack which I installed over the back wheel.

While I was waiting for it to arrive I drilled 2 holes in the bike frame so I could install the battery bracket.