My Electric Bicycle (E-Bike) !!!

Here is my electric bicycle conversion.

I started with a normal mountain bike, quite old I have to say, I guess it’s more than 10 years old.

I wanted to add an electric motor to the wheel because where I am living it gets really windy and it’s often very hard (and very annoying) to pedal. Also there are some short steep hills and I would greatly appreciate any kind of help uphill 🙂

The motor I choose is a Bafang 201rpm 36v 500w  geared hub. This kind of motor is part of the wheel and has internal gears and a clutch. This allows the motor to spin freely forward when not powered (downhill or simply pedalling). Also the motor is very light (less than 4kg including the rim) and efficient. The maximum speed at 36v is about 30kph. Please check the laws or bylaws of your state and/or city about electric (and/or PAS) vehicles, you may need to abido to speed or power limitations in order for your e-bike to be roadworthy.

This motor suits my needs perfectly because it’s designed for short hills and frequent stop & go and has a limited speed. If you are looking for speed and are travelling more on flat ground without stopping much it’s better to consider a Direct Drive motor.

For the motor to run you will need now at least three more things: a controller, a throttle and a battery.

If you are new to electric bicycles NEVER ATTEMPT TO CONNECT THE BATTERY DIRECTLY TO THE MOTOR. It may harm you and people near you. If you don’t know what to do or are not sure ask for help to a technician and/or competent person.

Thumb throttle with battery charge indicator.

Motor Controller

DIY Battery made from “dead” laptop batteries.

I ordered a kit online that included motor (already laced to the rim), controller and thumb throttle. Make sure that the motor you choose will fit the fork drop-out. The vendor can easily help you here.

Before mounting the electric wheel to the frame is better to check and make sure the spokes are tensioned properly. If you cannot do this by yourself you can take the wheel to a bike shop and they can do it for you (cost should be 10-20$).

If you are handy the assembly is pretty easy easy. Change your rear wheel with the electric one following the instruction given with the kit. Some motors have a lot of torque and require “torque arms” that reinforce your forks. Some motor have so much power that can easily snap your forks!

I mounted a rear rack on the bike and used a tackle box ($10) as a container for the controller and the battery. I’ve built a little rack in the tackle box so the battery can sit on top of the controller. This way I can take the battery out for charging.

To measure the amount of energy used and control the overall status (voltage) of the battery I installed a Watt meter. This tiny object will measure the power consumption and the voltage of the battery in real time, so I can gauge how much rage I have left.

I followed the instruction given by the seller to hook up the controller to the motor, throttle and battery. The watt meter is placed between battery and controller.


Et voilà! The bike is ready for the first road test!

As you see from the photo all the wires are a bit messy and the setup is not as neat as I want it. This is because I am preparing a little wooden box to put the battery inside the frame triangle. This will give the bike more balance and stability and will take away a lot of weight from the back wheel.

Feel free to ask any question!

3 thoughts on “My Electric Bicycle (E-Bike) !!!

  1. Congratulation it’s a nice conversion, here in Italy you cannot use a 500W , unfortunately the law limits the power to max 250W, additionally the PAS should assist until the speed is under 25Km/h 😦 then the controller stop to support you.

    As far as I understood the battery pack come from the recovered laptop cells you described on the previous post?

  2. I know, Italy is very limiting if you want to convert anything.Yes the battery pack is the one from the previous post!I estimate a rage between 55 and 75 km with it :). I am also trying to use a capacitor bank in parallel to the battery to reduce a bit the voltage “sag” during stop & go. I read somewhere that it can help to protect the battery too but I could not find any relevant data about it. I guess I will have to test and see :). Any news on your arduino-scooter?

  3. It’s very interesting the use of capacitor to provide a sort of support to the battery, I don’t know how should be implemented, but I’m curious to see your experiment…

    My project on Arduino vs Android is going well, yesterday I installed the BT adapter to Arduino and I made a first logging, it works good:-):-).
    Although my goal was even to read, in addition to the other sensors, the voltage of my 20 cells, I had to remove that part ‘cause it’s not working In the next days I will publish on my blog a demo to describe how it works in this version..

    Let us know about your project!!


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