Introduction: How to Make Geared Electric Bike
This project is very very special as I have made an electric bike that too India's first electric bike with four gears. I always use to wonder why no gearbox is used to make electric bikes efficient. Of course, the obvious reason I do know but still I wanted to know and experience what idea was there in my mind and so I decided to make one on my own. The idea behind making the geared electric bike was to make a commuter or street bike with an economy, green, zero-emission street bike that can easily carry any person, two persons and can cruise at a decent speed. It lags nowhere in the city's fast-moving traffic. Also can carry loads while climbing more than 35 degrees of slopes. I have made all of the above things to be true and working on the bike. The donor bike that I took was in very bad shape. This project took six months to complete as I wanted all of the above criteria to be present on the bike. How I made it and what all modifications are done to make this bike is all well described in this video. Basically, I took Bajaj Boxer and used only the frame and gearbox of the bike. For using four-speed gearbox on an electric bike, I had to replace the main crankshaft with the customized one. Also, a thick motor plate was fabricated for mounting the motor on the gearbox to make it a complete electric engine with four gears. This project came out really very good and even more than my expectations.
Many of my friends have asked me why gearbox and not hub motor, following are the reasons
1) Better torque on lower power motor.
2) electric vehicles are typically cursed for lower traction up hilling or climbing a slope that is eliminated in this.
3) overall lesser amps draw from battery due to gears improving the life of battery and efficiency of the entire system
4) higher load carrying capacity due to gears
5) I have just used a 1000watt motor which outputs barely 2000 rpm at the shaft but still, I have managed to strike a balance between performance and power just because of a geared system So I hope you have got all your doubts cleared over using the gearbox.
Note: English Subtitles available in video. The Video language is in Hindi. please turn on Captions in your youtube for that
FAQ: What is the top speed Answer: 47.5 Kmph in fourth Gear What is the Range Answer: 50 Kmph / Full charge What is the battery capacity Answer: 48v 24Ah
There is a lot going in for the making of this project and lots of efforts and hard work had gone for making this e-sculpture on two wheels. Your word of appreciation will be really a credit to my work.
Step 1: Taking a Donor Bike and Modifying Its Frame to Hold Batteries
The first picture shows the components or parts that will be removed from the engine and bike for electric modification. Bajaj Boxer is the 100 cc commuter bike that is commonly available in India. I got the bike at scrap value and started to work on it. All of the parts were taken off the frame. The frame was then fitted with the battery bay and batteries were installed on the bay and connections were made.
Step 2: Customized Parts That Were Made
An e-rickshaw motor 1000 watts 48v was modified. The motor is primarily made to be used with the rear differential gearbox of a three-wheel vehicle. There was a small gear on the shaft of the motor. I then turned that gear to the rounded shaft and made a flat part on the shaft to fix the chain sprocket with grub screws. The original engine crankshaft was removed and replaced with the customized shaft and the drive sprocket will be fixed on the other end where there was a magneto of the bike. The shaft pops out of the magneto cover where there will be a key slot to fix the bottom sprocket. Where there was a mounting for block and head assembly at that place motor mounting plate will be fixed. motor sprocket is also shown in the above picture.
Step 3: Electric Engine Assembly
The customized shaft was placed in the gearbox and the gearbox was then assembled as a regular bike gearbox along with all the gear and clutch functional. The gearbox will then be filled with regular quantity to 20W30 gear oil. This oil will probably last forever because this oil is not going to be burnt by the combustion engine.
Step 4: Gearbox and Parts Ready to Be Mounted for Electric Motor
As I have shown in some of the above pictures gearbox converted for the electric engine is ready along with the electric motor. Firstly the gearbox is mounted on the frame after that level plate gasket are placed and the motor mounting plate is fixed. After that part is completed the motor is mounted on to the motor mounting plate completing our electric engine installation with gears.
Step 5: Making BLDC Motor Wiring Connections With Controller
As like other regular electric bikes the motor, throttle, battery connections were made to the controller. Ignition switch wire was connected to motor enable wire in the controller. Twisting the throttle the motor and electric engine came to life.
Step 6: Primary and Secondary Chain Drive Installation
This bike has two chain drives. Primary chain drive between motor and gearbox and secondary chain drive between the gearbox and the wheel.
Step 7: Making a Cover for Battery Bay and Paint Work
The battery cover was made form the existing petrol tank by cutting it into two parts and then adding an iron sheet strap in between to bridge the two halves by welding so that it sits on the battery bay. Finally, all the parts were sent to the paint shop and I was eagerly waiting for the results.
Step 8: The Final Outcome and Taking It for a Spin
The final outcome of the project was mind-blowing. I took the bike for a ride and I cannot explain to you how satisfying and hair raising experience that was. The bike performs as expected and even more than my expectations. I would suggest you watch the video for a better understanding of the project. As mentioned earlier, the video is in Hindi but English closed captions are available on the video. I hope that this instructable was informative and enjoyable for you. I thank you all for your valuable time and interest.