DIY Motorized Bicycle




Introduction: DIY Motorized Bicycle

About: Being a science student i love to indulge in projects related to engineering as i love to learn things practically...

In this instructable I am going to show you how we can modify a stock bicycle into an electric one using a simple geared DC motor, a bunch of lithioum ion cells and a custom made speed controller.

The proect started as we found a geared DC motor that we have salvaged from scrap and later found out that its used to power automatic doors. The motor was very compact and have alot of torque and that kicked my mind to built an electric bike, the proect i was looking to work on for a while.

So let get into the built....

Step 1: Tools and Material

List of material for this project is:

  • A bicycle
  • 42V Brushed DC motor
  • 18650 Lithium ion cells
  • Speed Controller ESC
  • Wires
  • Connectors
  • Angle iron
  • Gears

List of tools used in this project is:

  • Drill machine
  • Drill bits
  • Angle grinder
  • Welding plant
  • Soldering iron

And some kind of basic tools like pliers, cutters and wrenches etc.

Step 2: Making the Drive Mechanism

First of all we have decided to power our bicycle using a simple brushed DC motor, that we have find out from an old sliding door mechanism. After considering a lot of factors we have decided to make simplest and reliable drive mechanism and for that we have welded the 21 teeth gear along with 2" inch metal pipe spacer on the rear disc brake plate in order to rotate the wheel using geared dc motor.

Step 3: Attaching the Pinion Gear to the Motor

After making the drive mechanism its time to attach the pinion gear on the motor and for that we have used the 16 teeth one way pinion gear in order to rotate the wheel along with with motor. A metal washer is welded to the rear side of the pinion gear. Three holes are drilled across the washer and the pully on the motor to mount the pinion gear on the motor pully.

The reason behind using a one way pinion gear is to let the rear wheel spin freely even when the motor stops moving.

Step 4: Making the Motor Mount

In order to mount the motor on the bicycle frame we have made to card sheet templet in order to find the best position on the frame and then we made the mounting piece using 3 inch angle iron piece and then we drill the holes using hand drill for mounting the motor to motor mount.

Step 5: Mounting the Motor on Bicycle

After mounting the motor on the plate its time to mount the motor on the bicycle frame and attach it to the drive mechanism and for that we have decide to make the drive mechanism as compact as possible and then we use the 6mm L-key bolts in order to mount the motor on the frame.

Step 6: Battery Pack

To power our electric bike sufficiently we have used 18650 lithium ion cells that we have extracted from our old hoverboard batteries.

We have used two battery packs each of which contains 20 cells.We are goign to use two battery packs, so in total we are going to use 40 pcs of 18650 cells. Since the BMS(Battery Managment System) unit we salvaged from the hoverboard battery pack is capable of handling upto ten cells connected in series so we are going to form the battery pack in two parts. Each part contains two cells connected in paralled and ten of them in series. Now to have the required output of nearly 84v we are going toconnect both the packs in series using an external jumper cable.

Step 7: Enclosure for Battery Pack

In order to protect our battery pack from short circuit and to give it a nice look we have decided to built the enclosure for battery pack. We have used 5mm acrylic sheet cut it into exact dimension for the battery pack and glued all the piece pieces using super glue. The enclosure is then painted in matt black that gives it a pretty nice look.

The battery pack is the mounted inside the enclosure with a pair of XT-60 connectors popping out as the output of each battery pack which is latter going to be connected in series to have the required 84v output.

Step 8: Customized Speed Controller

Since the bicycle needs to be powered at 84v so to regulate the speed of the bike we need a PWM controller. But the problem is that most of the controllers avliable online are unable to handle that high voltage.

Here I would like to thank PCBWAY as with their help we were able to design a customized speed controller thats capable of handling upto 90vDC and nearly 2000 watts of power. After finilizing the schematic and the PCB designs, the guys at PCBWAY did a great to provide us customized PCBs to built the controller. So guys be sure to have a look at their webiste for great quality products.

Step 9: Attaching the Speed Controller (ESC)

In order to control the speed of our electric bike we have decided to use PWM speed controller that can handle higher amount of current so we use 5V-84V DC motor speed controller that we have made in our previous instructables projects and that speed controller is capable of handling load upto 2000 watt.

So we have mounted the ESC using tie clip on the top of the handle bar and we extended the wire for power button and for the twist grip throttle as well.

After that we have secure the input (84V DC) and output (motor) connection for the speed controller.

For more detail about DC motor speed controller links are as under:

YouTube Link:


Schematic,Gerber files and Components list:

Schematic,Gerber files and Components list:

Step 10: Final Result

The conversion was for sure a sucess. The bicycle seems to run smoothly and we are able to achieve a moderate millage on a single charge though we are unable to measure the millage per charge as the battery pack seems to hold up preety long. Besides that the max speed we hit was nealry 30Km/h which was half of the speed that we can get from this bicycle. The reason behind that is relatively large current draw at full speed which is hopefully due to the inefficient brushed motor.

We are lookinbg forward to improvise the performance by using a brushless motor in one of our upcoming project so stay tuned for that and dont forget to drop your suggestion bewloz, would love to go through them.


DIY King

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    2 years ago

    Your use of a one way sprocket to achieve a coasting function was a good thing. Since you have already worked out the batteries and speed controller I suggest you keep the same motor but eliminate the worm drive gear box, as a cost effective way to get better performance because while the worm drive is good for applications that require high torque, there is a penalty in motor efficiency. By building a plate with a bearing to suit the dimensions of your motor you would also then need to mount the motor horizontally.


    Question 2 years ago

    appreciate your works ! any reason why the switch from JLCPCB? I used your link for the induction board and looking forward to building that soon.. just wondering thanks.. also , how can we donate? God Bless my friend : )


    2 years ago

    Well done DIY King. Till the end of the video I was assuming it is shot somewhere in Indian city. Then realized your name and reminded you are from Karachi. So similar our countries are, food, language, streets, surroundings, songs everything etc. Dont know why are they apart. One thing is clear, China is eating both countries jobs, culture, food etc. BTW good job. Best wishes for your next BLDC motor project.

    DIY KING 00
    DIY KING 00

    Reply 2 years ago

    Your words made my day brother. Thanks alot.

    And I guess thats what all of us need, appriciation to get through the ups and downs in our life.
    I never get the idea of peoples getting crazy to figh oneanother from both countries which logically isnt possible. But some of the best peoples still exists in this world and we must hope and work for betterment to built a place where we encourage each other and eventually grow together.

    Peace man.

    Rao Abdul Samad
    DIY King


    Reply 2 years ago

    Thanks Abdul. In the flood of emotions, I have just forgot to mention that the overall presentation of your project and the video & photography is also excellent. Keep it up. Best wishes.


    2 years ago on Introduction

    Where did you get the electric motor?

    DIY KING 00
    DIY KING 00

    Reply 2 years ago

    From a scrapyard


    2 years ago

    PCBWay Donate 10% cost To Author The board costs $89
    In fact this seems to be about pushing and publicising this PCB maker . When you go there the prices are astronomical. Reduce the voltage if you must and get the ESC back to reasonable prices. Link does not work!