Hello from Northern California!


New Member
Hello! I've been tinkering with ebikes for about a decade now. Being an engineer, DIY is my preferred route. My first bike was built a decade ago on a Kona Nunu, 26" hardtail using a GnG motor. I rode that thing all over SF, but it wasn't the most reliable setup. Upgraded it over time with Lightning Rods kit, Cycle Analyst, Lyen controller, etc. Built a custom battery box for it, and certainly "got my money's worth" from all that stuff. Over time, the mechanics just kept getting more noisy, unreliable, etc. The basic motor and electronics was fine, but the drivetrain was showing its age. The bike sat in my garage for a few years until last year, when under lockdown and lack of physical activity, I decided to "reboot" the project.
I had been reading about the Bafang motors for a while, and it looked like it would be worth trying. I ripped out all the old GnG faff and put in a Bafang BBSHD 1kW motor with a Lekkie chain ring. All I have to say after the conversion is "WOW". It was nearly silent, smooth, and vastly more reliable than my old gear. I even upgraded the fork on the bike and various cockpit bits. A really big plus for the Bafang system is its PAS capability, which the GnG lacked. I had to rely mostly on the throttle on the old setup, but now, I almost exclusively ride with PAS, with the occasional flick of the throttle to get going from a dead stop.

Being a hard tail bike, it was fine for a city ride. I could get to just about any part of the city in about 15-20 minutes. But I started to yearn for a proper trail bike, and one that was more up-to-date for 2021. Also, here in northern California (e.g. in Auburn and Nevada City), we have extensive trails that I wanted to explore with a proper trail / enduro eMTB.

Because I appreciate the power that's possible when you build your own bike, I wanted to build a proper bike around a modern Bafang motor and set out to research frames. I was inspired by "Rob Rides EMTB" CHEEB project. I thought, this is it! Alas, it appears that you can't buy this frame in the USA because someone (the rumor is LUNA) has bought exclusive rights for this frame.

So I went searching on Alibaba for other all-mountain / enduro style frames built around the M600 motor. Although not as powerful as the BBSHD, the M600 is twice as many watts as available in any ready-to-ride bike. Plus, I found that the 1kW on my current bike was really an overkill in most of my riding. And with the new wide-range gears now available, steep climbing shouldn't really be a problem.

I found a CF frame from an unknown manufacturer called "TopFire". Their MD-17 frame geometry looks to be quite modern: slack, long, and offers 150mm F/R travel. I've ordered the frame with a custom paint job, and hope to take delivery in a month or so. I've been buying parts from all over the web and have collected everything I need. Highlights include Bafang M600 motor and BTF04 battery, Fox Factory fork, shock and dropper post, Shimano M6100 12sp drive train, Maxxis tires, Wolf remote, Ergon saddle and grips, Crank Bros pedals. I did a Photoshop rendering of the frame with the selected components:

Even if the frame turns out to be crap, there are others out there that are almost identical. It appears that these designs and molds are being made by different factories, so, I'm not too worried about the risk. I'll let you know how it turns out!