Luna Cycle custom build on a Specialized Rockhopper 29er.

Bafang BBSHD 1000W Mid Drive Kit
(Bottom Bracket Size: 68-73mm (Standard), Chain Ring: Stock 46T Steel Chain Ring,
Luna Aluminum Chain Ring Adapter With 42T Sprocket $40.00,
Display Options: C965,
Bafang BBSxx Universal Thumb Throttle,
Bafang Handles with Built-in Ebrake cut off,
Shark 52v PF 11.5ah $439.95,
52v 3amp Lithium Charger $30.00

Used 2009 Rockhopper 29er from Craigslist 250
BBSHD 1000w mid-drive kit 669
Luna Cycle chain ring 40
Shark 52v PF 11.5ah 440
3amp charger 30
Shipping 60
Total Cost (not including special tools) 1489


The total build time was about 4 hours over a couple of days. Most of the time was removing the existing parts from the donor bike. This was a great kit with everything needed included (except for zip-ties). I did have some existing tools such as hex wrenches, pedal wrenches and a chain brake. I also had to purchase some tools which I found through links in this forum and other forums. Total cost about $55.The hardest part of the build was removing the existing crank, pedals and bottom bracket. These where on the bike since new and required some angle grinder work to get them off. Once they were off, everything went smoothly.

2 custom things I had to do on this bike.
  • Because the chain stays jut out sharply (see the pics) I had to add a couple of the included spacer rings to keep the internal crank of the motor (on the drive side) from contacting the chain stay. If I didn't use the spacers the drive shaft would not have been able to be seated properly in the bottom bracket.
  • The triangle on the Rockhopper is very small, and I was worried that the Shark Pack I bought would not fit. Luckily it just fits, but I did have to drill new wholes for the bottom bracket nuts as the existing ones where too low in the triangle to mount the battery holder. I bought rivnuts and affixed them using the method recommended by RJ The Bike Guy (thanks RJ!) rather than buying an expensive rivnut tool. I did use an angle drill (see the pics) to drill out the wholes for the rivnuts, but with some patience it could probably be done with a regular drill.
Other comments.

The bike was about 25 lbs without the kit and about 50 lbs after installation. With a 180 lb rider, it will do about 33 mph on the flat at full throttle. I get about 25-30 miles on a charge, but that's pushing the motor pretty hard (generally 3-7 PAS). I don't use my lowest 2 gears because the chain line is at quite an angle and I don't trust driving it like that. A lekkie bling ring might be a good option as it looks like it's fairly deeply dished and might line the chain up better.

that's about it. Here's a couple of video links:

short spin

commute to work
Attached Files