There are a lot of projects that you can take up over a short period of time; start, complete, enjoy, and use. This project may, if you’re not careful, lead you down a path of obsession.
Motorcyclists are generally rabid enthusiasts, and some electric motorcycle builders are quite new to motorcycling, having come from the electric vehicle path. Electric vehicles are riding a wave of technology development. Combining the two can be electrifying.
Common reasons range from environmental to economic. Some people do it just to save gasoline.
The deeper implications of building an EV, especially one salvaged from the junkyard, can get interesting. Some people just like being backyard mechanics. Many builders like keeping about 500 pounds of scrap out of the junkyard by salvaging, and sometimes restoring, vehicles that others have passed off as not worthy of repair—it’s reduce, reuse, and recycle. And by solar charging, EV/PV enthusiasts can power their rides with completely renewable energy—a 0% carbon footprint.
Many love the attention their unique vehicle gets, using them for RE evangelism wherever they go. They spark questions, conversation, and enthusiasm for the work and ingenuity to convert a gas bike to electric, even among hard-core motorcyclists.
Electric trail bikes have their fans because they open up areas to riding that, because of the noise of gas trail bikes, might not be tolerated.
There is, however, one thing in particular that stands out about electric motorcycles: the power. Electric motors deliver power in a completely different way than their gas counterparts. Power (torque, in particular) is instantaneous, and the power increases the faster the motor spins. There’s no gear shifting, and going from 0 to 60 feels like holding onto the tail end of a rocket. Many people build an electric motorcycle simply because it’s an affordable way to experience the feeling of an ultra-high performance electric drive train.
Going into your project, have a clear and realistic idea of what you want to accomplish. Assess your skill level, and determine the type of donor bike, the desired performance, and how you want to use the completed bike.
Aiming for 100 mph top speeds with a range of more than 100 miles is a recipe for disappointment. Start with a more conservative target: Most bikes can hit a top speed of about 75 mph, with a range of 30 to 40 miles.
Don’t grab the first donor bike you see if it doesn’t suit your plan. Too often people try to make a heavyweight cruiser out of a medium-weight sport bike; a lightweight café from a monster frame; or even a street bike out of a trail bike chassis. Start with the style and weight that you want to end up with.
Check the condition of the chassis you are considering. You need a safe, reliable ride, so consider the brakes, tires, bearings, and suspension, just as if you were buying a gasoline-fueled bike. To register it, it’s got to have a clean title.
The permanent magnet DC (PMDC) motor has a good price, fairly simple control systems, and reasonable weight and efficiency. Brushless DC (BLDC) or AC motors don’t need maintenance, operate at a high rpm, and the controller electronics allow more precise motor control. They are heavier and more expensive, but have more power capacity.
Most motors are mounted where the gas engine used to be, but designing and building a motor mount that’s in the right spot and can handle the stresses of the higher torque requires fabrication skills and careful planning. Another option, the hub motor, is integrated into the rear wheel of the bike, eliminating the motor mount, chain, sprockets, and space in the frame demanded by conventional motors.