I started designing and tinkering with conversions, when I bought a used Haibike XDURO (MY 2017). It was to replace my self-built TREK hardtail (MY 2011) ebike and enable me to get into mountain biking.
Unfortunately, after a short time it turned out that it didn't meet my requirements: the battery was too small for longer rides and the motor was too weak for steeper terrain. What to do now? Sell it on? Buy a bigger battery? There was no conventional solution for these points and the search for alternatives began...
I was very happy with the Bafang BBSHD, a Chinese mid-motor, on my hardtail. Spare parts from Bafang were easily available and the motor was easy to use with any standard battery. During this time, a friend told me about the Bafang Ultra G510/M620, the big brother of the BBSHD. However, this motor required a special frame with a suitable motor mount. My friend asked if it could fit in my Haibike and unknowingly, by this question, he started something.. After doing some research, it turned out that I wasn't the first person to try to integrate a Bafang Ultra into a Bosch frame. "KaroKönig", from the pedelec forum, had already done something similar with his CUBE frame:
I liked the idea and it spurred me on to try a similar conversion. Until then, I had only fitted the TREK hardtail with a BBSHD and added the battery. With the experience I had gained, I was able to estimate what lay ahead of me. So the decision was made and I ordered a Bafang Ultra!
I started by removing the Bosch motor and finding a suitable position for the new motor. To do this, I used the angle grinder to cut out parts of the motor mount to create space. The stability that was potentially lost was later restored by the transverse screw connection with the adaptation plates and motor. As I didn't have any 3D models, I had to resort to a conventional method for the development:
Cardboard Aided Design (or "CAD" for short 😉).
Switching from Bosch to Bafang also allowed me to use the battery from my hardtail on both ebikes. I was also able to build a battery that met my requirements and was big enough for longer tours. 😀
This first conversion prompted me to look further into the subject. Over time, more and more people contacted me who also wanted to convert their ebike. It motivated me and I tried to develop general solutions for similar frame types. The result is right in front of you! 😉