In this build guide I will show you how you can make my personal favorite DIY ebike build. I really like riding this ebike, it's really fast and it has amazing pedal assist. You can even use the throttle so that you don't even have to pedal. The mid-drive allows you to use gears, which is really convenient. You can use all the power of the motor to get up steep hills in a low gear or reach high speeds in high gear. The acceleration of this e-bike is also on another level in low gears. I made a very detailed YouTube video that shows how to build this exact ebike. I advice you to follow this video, this will be easier than reading this instructables.
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Step 1: Get the Parts
The parts can be ordered through aliexpress.com, all the order links can be shipped internationally without taxes. I only list trusted sellers, where I also buy my personal parts. The bike can be bought at Decathlon worldwide.
Bafang BBS02 750 Watt + Battery + charger + display + all other parts:
In the video I have the 44T chainring and the DPC-18 TFT display (choose C965 Display if on a budget).
This kit includes all the conversion parts you need like: e-bike brake levers, throttle, display, control unit, motor, battery, charger and mounting hardware.
Gear sensor (recommend):
Programming cable (if you want to reprogram your controller):
Bike light (optional, can run of the e-bike battery and turned on via display):
Bike (Rockrider ST 520):
The bike I used is available at Decathlon, here are the links of the most popular countries. If your country isn’t listed below you need to see if there is a Decathlon in your country. Decathlon is in 54 countries, so there is good chance you can get this bike in your country.
The specialized tools you will need, to make this e-bike are listed below.
Crank removal tool:
Decathlon also sells the correct bottom bracket tool that I used in the video. I prefer that one. Otherwise get the one below.
Bottom bracket tool:
You need either tool 1 or 2, tool 2 is easier because it uses chain quick links and can be used on the Rockrider ST 520 bike.
Chain removal tool 1:
Chain removal tool 2:
Step 2: Remove Chain, Bottom Bracket, Crank Arms and Front Derailleur
Using the Youtube video you will be able to easily build the e-bike. Even inexperienced builders can build it using the video. The video includes all the necessary steps. Everything is shown in detail, to make is easy to follow. If you have any questions about the build. Please leave a comment. This instructables will be way more general, so use the video for all the details!
You first have to remove the chain, bottom bracket, crank arms and front derailleur. You do this by unbolting all the bolts and using the special tools (listed above) to remove all the parts. You now should have a hole in your frame and a removed front derailleur. The bike is now ready to take the motor.
Step 3: Install the Bafang BBS02 Motor
Slide the Bafang motor into the frame. The Bafang motor should fit nicely. Secure the motor using the included mounting hardware. Make sure you install it's really tight. The motor has a lot of power and will loosen itself if it's not secured enough.
Step 4: Install Chainring and Cover
Install the correct size chainring for your bike to the motor. The default chainring is 44T and will fil most bikes. Make sure you tighten the bolts enough. Don't overtighten the screws of the chainring cover.
Step 5: Install Speed Sensor and Gear Sensor
Install the speed sensor and magnet using the included mounting hardware. Make sure the magnet is close enough in order to be detected by the sensor. The red light should blink when the magnet passes the sensor. Installing the gear sensor is optional. You don't need it, but it's nicen to have and I recommend installing it.
Step 6: Install the Battery
If you buy the battery from the source I provided, you only have to secure two bolts. You screw in the battery mounting plate to the water bottle mounting holes. You then connect the battery and motor using the connector. No soldering required.
Step 7: Install Display, Control Unit and E-brake Levers
Install all the necessary hardware for the e-bike. All these components are included into the motor battery kit. You just have to install them to your bike.
Step 8: Manage All the Cables
Connect all the connectors together. All the connectors are colour coded. Manage all the cables using tie-wraps. Make sure the wires are nicely managed in the end.
Step 9: Reinstall Chain, Crankarms and Pedals
Reinstall the chain using the quick links. Slide on the crankarms and tighten them really well. The pedals you can easily screw in.
Step 10: Go and Enjoy Your E-bike!
You are done building you e-bike. You can now enjoy your really fun to ride e-bike!
Step 11: Find More Information
If you want to know more about DIY e-bike building go to:
If you want to know more about this ebike build go to: