An electric bike (e-bike) conversion kit is a great way to breathe new life into an old, neglected bike. After spending some time researching the two main types of kits available (mid-drive and hub motors), I finally decided on a Golden Motor Magic Pie v5 hub motor.
This kit replaces the bike's rear wheel and includes a throttle as well as new brakes that will cut power to the motor while braking. Having never worked on bikes before, it was certainly a bit stressful at first, but in the end, it turned out to be much easier than I had expected and only took 2-3 hours to complete.
Step 1: Selecting a Battery Pack
Selecting a battery pack can be a bit confusing. There are several different styles to choose from, cell manufacturers, voltages, and amp-hour ratings. The motor will specify the voltage range that is allowed, and it is important to get a battery pack that falls within this range. A pack's amp-hour (ah) rating will dictate how far it can go on battery power on a single charge. And speaking of charge, a good battery charger is also important, though most battery packs will come with one (or at least recommend one).
Panasonic and Samsung seemed to be pretty popular choices for high-quality cells, so in the end, I decided to go with a 52V 13.5ah Panasonic NCRB bottle battery pack. It installs in the drink bottle mount on the bike's frame, so it's a little less noticeable other than it looks like I drink a lot of water.
Step 2: Removing the Rear Wheel
The first step to installing the hub motor was to remove the rear wheel. I started by loosening the brake cable and then the wheel's quick release lever. Then it was just a matter of holding down the rear derailleur while lifting up on the wheel to remove it.
Step 3: Removing the Existing Freewheel
Step 4: Removing the Existing Tube and Tire
Since I planned to reuse my existing tube and tire, I deflated the tire and used a set of tire levers from a small bike kit to pop the tire off.
Step 5: Installing the Tire and Freewheel
After transferring the tube and tire to the new wheel, I installed my old freewheel onto the Magic Pie hub, being sure to use the included washer as a spacer to prevent the freewheel from binding. (Note that to get the freewheel back off the motor, the hole through the freewheel remover tool must be widened with a 9/16″ drill bit as the axle is fairly thick.)
Step 6: Installing the New Wheel and Torque Arm
The next step was to put the wheel back on the bike. I added two of the included washers to the axle on the freewheel side — these prevent the freewheel from binding on the dropout. I also added a lock-washer on the other side and then placed the wheel back on the bike. Once the wheel was fully seated in the dropout, I used the remaining lock-washer and secured it with the axle nut on the outside of the dropout.
On the other side, I attached a universal torque arm for additional safety. I then added the remaining axle nut and tightened both sides down very securely with a 7/8" socket wrench.
Step 7: Running Wires
There were several wires that need to be run along the frame of the bike, so I just took my time and secured them with zip-ties.
To avoid cutting the wire to the battery, I simply looped it around the seat tube. I then connected it directly to the battery mount which installed easily in the holes for a water bottle holder.
Step 8: Installing the Display and Controls
With the wiring mostly complete, I removed the handlebar grips using my air compressor to blow air inside the grip. Then I loosened and removed the shifters and existing brakes.
Next, I mounted the display to the center of the handlebars. On the left handlebar, I installed the included throttle and e-brake (cuts power to motor when braking), as well as the controls for the display. Since space was a little tight, I decided to not re-install the 3-speed shifter for the crankset. On the right handlebar, I installed the cruise control switch and the remaining e-brake as well as the 7-speed shifter that came with my bike.
Step 9: Completing the Installation
After reinstalling both grips, reconnecting all the brake cables, and performing a little more cable management, it was finally complete!
A quick test ride proved that this motor and battery combination are pretty amazing! I was able to easily reach 30 MPH on throttle alone, and the acceleration is enough to cause you to pop a wheelie if you’re leaning back. I can definitely say that it is more than enough power for me at 170 lbs.
Unfortunately, it needs to be reined in a bit to comply with local laws (and the wife). These laws tend to vary quite a lot by location, so be sure to do some research before shelling out cash on a souped up e-bike.
Step 10: Programming the Magic Pie Motor
In order to adjust the motor’s settings, I purchased a USB programming cable. This uses the plug from the motor that the display unit normally connects to and has a USB connection on the other end that connects to a Windows PC.
[Note that there is an option to use a Bluetooth adapter with an Android app, but several people (including myself) have currently been unable to get the app to work properly.]
Once I installed the appropriate drivers on my PC, all that was left was to plug the cable into the computer and run the configuration software. There are several options that can be adjusted including max speed, acceleration, and regenerative braking. After a few tweaks to the motor’s settings, I had everything running within limits and the acceleration was nice and smooth.
Step 11: Parts and Tools
- Golden Motor V5 Magic Pie Kit (with LCD Display)
- Golden Motor Programming Cable
- 52V Panasonic 13.5ah Bottle Battery (48V version)
- Universal Torque Arm
Step 12: Conclusions
I wasn’t sure how hard it would be to do the conversion, especially since I had never done any real work on a bicycle before, but it turned out to be quite easy. Certainly not as easy as buying a new electric bike, but that would have also cost a good bit more for similar features, and this way I was able to reuse my current bike. So far the results have been great, and it's certainly a lot more fun to ride around!
Note that since there are several types of electric bike kits and many different bike designs, be sure to follow the directions from whichever kit you purchase carefully!