Wednesday, January 14, 2009

48V Electric Flat Tracker
About a year ago, my dad and I had the idea to convert a beach cruiser bike into an electric motorcycle. We purchased the bike and all the parts necessary and got to work. We modified the frame and rebuilt the bike from the ground up. When we finished, we were extremely satisfied with the results - a 48 volt, 15 horsepower board track racer.

We started with a Felt beach cruiser because it had the right look. We wanted a beefy bike that could fit all the components. The goal was to keep the center of gravity as low as possible. Here are the rest of the main components we purchased:
- Briggs and Stratton Etek motor (now discontinued)
- Alltrax AXE 300-amp programmable controller
- Magura 0-5K ohm twist-grip throttle
- 4 x 12V, 21Ah sealed lead acid batteries
- Avid BB7 mechanical disc brakes (160mm rotors)
- #35 moped chain
- 13-tooth drive sprocket
- 66-tooth rear sprocket
- big power switch
- 300-amp fuse
- 8 1/4 in. stainless steel motor mount (this replaces the original bottom bracket)

Seat Mount
The original seat post was removed, cut short, and welded on the seat stay bridge over the rear tire and a gusset was added for strength. A rubber cap was put over the existing seat tube, and the seat clamp was flipped and reversed.

Rear Drive Complete
Here the brake mount is welded on, the wheels have been laced to the hubs, and on the right side, the seat stay has been crimped to get clearance from the chain and sprocket. The axle tension adjusters we used were from Answer Products.

Final Assembly
After we had finished the assembly, we had to wire it up. Within a few hours, we were testing it up and down the parking lot. It really accelerates quickly and we have not tested it for top speed. It is estimated to do better than 50 mph.
The controller we used can connect to a PC via a serial (RS-232) cable. With the freeware on their site,, you can view statistics in real time, change settings, and adjust the power curve for the throttle.

Source, with many more steps and build pics.

Labels: ,


Post a Comment

<< Home