How to Build a DIY Electric Mini-Bike of Your Own
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Fancy building your own e-bike? Then this great little project is right up your street. Happy building.
Like any project of this nature, you are going to need some stuff first.
Tools and equipment needed
- Azusa Minibike Kit with Aluminum Tri-star Wheels
- 7KW Brushless DC Motor
- Motor axle sprocket
- L bracket
- e-Bike accelerator
- xt90 anti-spark key and harness
- 5mm bullet connectors
- Duct tape
- Power tools
- Spray paints
- Various nuts and bolts
Step 1: Build the frame
The first step is to unpack and begin constructing your mini bike's frame. This particular bike comes courtesy of Azusa Parts (link above). You could, of course, attempt to build the entire thing from scratch, but why reinvent the wheel if one is already going?
With all your parts out of the box, the next step is to prime the frame. Depending on the final look of your particular bike, choose an appropriate primer.
Once the primer is dry, you can then apply the surface paint -- in this case blue.
Once all the paint is dry, the next step is to begin the assembly of the frame. Take the handlebars assembly, grease up the connecting bolt/rod, and connect it to the body frame.
Do as much as you can by hand, and then, if needed, finish off pushing the rod using a hammer. Secure the bolt from the bottom using its matching nut. Tighten using a ratchet as needed.
Step 2: Complete and add the wheels
With that complete, the next stage is to assemble and attach the wheels. This kit comes with a matching pneumatic tire, so assemble as instructed by inserting the pneumatic tube within the rubber tires first.
Remove the valve cap, and partially inflate the tube.
With that, you can now insert the kit's matching tire hubs. These come in two halves -- which is handy.
Add the securing bolts to one half of the hub, as needed, and then match insert into the tire. Add the second half of the hub to the other side, and bolt them together, as needed.
Rinse and repeat for the other tire with the exception that the driving wheel needs an added sprocket for the drive chain.
Tighten by hand and then finish off using a ratchet again. With the hubs inserted, you can now fully inflate the tire tubes -- in this case 30psi.
With the wheels now complete, you can now mount them to the bike frame. Position the tires as needed, and then feed through the axle between the frame and hub, as needed. Don't forget to add the steel spacers too between the wheel and the frame along with the axles.
The fit might be a little tight, so make use of your trusty hammer once again. With the operation complete, secure the axle into place using their retaining nuts and test that the wheel can spin freely about its axle.
For the drive wheel, the process is slightly different, once again. You will also need to add the brake drum to the axle when attaching the wheel to the frame. Do so as instructed, and use a hammer and ratchet, to tighten the retaining nuts as needed.
Ensure the brake drum lines up with the specially welded retaining bolt on the frame -- it will fit in the elongated forked part of the drum.
Tighten using your ratchet as needed.
Step 3: Add the brakes and seat
The next step is to begin adding some of the bike's systems. Let's start with the brakes and brake lines.
Take the brake assemblies and begin to attach them to the handlebars, as needed. Then begin to add the bolts and nuts needed for the rear brake disc assembly.
With the main parts attached, add the brake cables, and secure/tighten as needed.
Feed the brake line through the frame, and attach it to the brake lever, as required.
Thread the cable through the groove at the top of the brake handle, and secure it in place using the locking mechanism at the other end of the brake handle.
With the brake system basically done, you can now begin to add other parts of the bike, like the seat.
Take the saddle piece, place into position on the frame and secure it into place as needed.
Step 4: Add the drive chain
A note about the chain at this point. Depending on the motor, brackets, etc, chosen, you may need to make your own custom-sized chain rather than using the one that comes with the kit. Bare that in mind when planning the build.
Now it is time to give the bike some actual propulsion. Take your brushless motor and add 5mm bullet connectors to its wiring. This is to enable the motor to readily connect with the other parts of the electrical system.
Remember the main bike kit is not designed to be electrically powered, so the electrical drive chain system is something of a modification to its standard design.
Next, grab your L-brackets, these will be used to mount the DC motor to the bike frame. If appropriate holes are not already present, mark out the motor mounting points to the L brackets and drill new holes to match.
With that complete. position the motor (and bracket) into place on the body of the bike. Then add the motor axle sprocket, and connect the drive chain between the motor and the rear-drive wheel's sprocket.
Move the motor assembly until the chain is tight, and then mark out where the mounting screws will need to be on the bike frame. Drill the holes, and mount the motor assembly to the frame, as needed using bolts, nuts, and washers.
Secure all parts as needed before moving on.
Step 5: Complete the electronics
With the main propulsion system complete, we can now move on to the electronics. First, grab your throttles, one will be used for the motor, the other for the brakes.
These throttles will be connected up to the electrical stability control (ESC). To connect them, you will need to make a custom 6-pin connector that will, in turn, connect to the wiring of the throttles.
Connect the positive wires from each throttle together as well as to the ESC port. Do the same with the negative wires. The input wires from each throttle will then need to be connected to the ADC ports on the ESC as needed (ASC1 for the throttle, and ASC2 for the brake).
If that sounds a little complicated, you can find the electrical schematic below.
Next, take the battery, and connect it to one port of the anti=-spark key harness.
Next plugin the ESC to another port in the loop key. Finally, plug in an anti-spark key into the third and final slot. To turn the e-bike on and off, you will simply insert and remove the xt90 into the harness.
You will know that the system is working by the small blue light on the ESC.
Next, take the three-phase wires from the motor and connect them to the matching wires on the ESC. You will also need to connect the sensor wire to the sensor port on the ESC.
Make sure that the battery is not connected when completing the wiring to prevent accidental electrocution.
Once ready, connect the battery, add the key, and test the motor using the throttle. The motor should respond immediately. If it does, you know the system is all good.
If not, check, and recheck your wiring and adjust accordingly.
Next, you'll need to correctly calibrate the throttle and brake to the ESC. Connect it up to a computer and follow the setup guide that should accompany the system.
Once everything is working as it should, you can go ahead and install the throttle to the handlebars of the bike. Secure as needed.
You can then begin to secure the cabling using the clips that come with the bike kit to the frame.
Step 6: Add other parts of the bike as needed
Next, you can begin to install the other features of the bike. Things like the footpads that come with the bike kit can be mounted to the frame, as required.
These can be adjusted to your liking. At this point, you can also do some more modifications like trimming off any excess parts of the L brackets that mount the motor to the frame.
You can now also mount the battery and other electronics to the bike frame as needed. The creators of this video used a large amount of duct tape, but you can make a more professional job if you want to.
In this case, the ESC and battery were mounted underneath the seat.
With that complete, some extra details can then be added like shred lights or other LED lights for e-bikes. Mount them to the frame of the bike as needed. These will act as headlights for dusk to dawn bike riding.
You will also want to add a rear driving light too to ensure others can see you in the dark if you want to drive your bike at night.
With that, your mini e-bike is complete. Feel free to add more flourishes to the design, and customize it as much as you want. Now you can get out there and take it for a spin.
If this project has whetted your whistle for custom e-bikes, why not consider upping the ante and building one from scratch!