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  • Matt

eBike MTB Conversion Project

[March 14, 2021]

BBSHD and Wolf V2 build on 2006 Specialized FSR Stumpjumper

I finally pulled the trigger on doing a build with my old Stumpy. I knew I wanted as much battery and power as possible and landed on the Luna BBSHD kit, but what battery?? My biggest concern was where to put the battery. After cutting out the templates Luna has online, and fiddling prior to ordering, I decided I needed to restore the bike a bit first to see if it was truly viable and what all I would need past the ebike parts. After a wash, new cassette, new chain, lots of lube, new brake pads, new shifter cable, new grips, rebuild on the original shifter and switching over to tubeless on the stock rims, I felt I had something that still had plenty of zing.


The Wolf V2 was very close to too big for the triangle, but seemed like it would fit. Onward!


I should say this is my second build of a Bafang mid-drive with my first being on a cargo bike. Aside from the battery fitting, I had no idea how tough the bottom bracket would be to get out. I have the tools and confidence, but that is where I tend to break stuff. :-)


Build of materials:

1. BBSHD kit: Bottom Bracket Size: 68mm-73mm (Standard), Bafang BBSxx Left Thumb Throttle, Ebrake Cut Offs: Hydraulic and Disc Brake Sensors with Cut Off (Pair), GearSensor, Custom Luna Eclipse Face, Luna Eclipse Sprocket 42T

2. Luna Perfect Pedals

3. 52v Luna Wolf V2 LG MJ1 13.5ah

4. LUNA Wrench BBSHD and BBS02 Mid Drive Installation Tool

5. 4.5mm of bottom bracket washers (spacers)

6. Eggrider V2 display


Pulling off the front derailleur, removing the bottom bracket. Was all cake. The pedals were a pain, but that is what breaker bars are for. I quickly had a bike ready for the mid-drive. In it goes no problem. Plenty of room. After putting on the nuts, playing with the included spacers, I realized the new sprocket was just barely nicking the frame. No good. I ended up using the spacers on the two bolts that connects the Bafang mounting plate which are included with the kit. However, this gave me a screwumpy un-flush mounting plate (I forget what this part is called, but it is the plate that bolts to the motor and digs into the frame to keep things secure, I will name it properly in an edit). This un-flush aspect is breaking a cardinal rule. This plate must be flush. So, I had to order number 5 above and add them to the sprocket side. Perfection was achieved.