Depending on local laws, many e-bikes (e.g., pedelecs) are legally classified as bicycles rather than mopeds or motorcycles. This exempts them from the more stringent laws regarding the certification and operation of more powerful two-wheelers which are often classed as electric motorcycles. E-bikes can also be defined separately and treated under distinct Electric bicycle laws.
Controllers for brushless motors: E-bikes require high initial torque and therefore models that use brushless motors typically have Hall sensor commutation for speed and angle measurement. An electronic controller provides assistance as a function of the sensor inputs, the vehicle speed and the required force. The controllers generally allow input by means of potentiometer or Hall Effect twist grip (or thumb-operated lever throttle), closed-loop speed control for precise speed regulation, protection logic for over-voltage, over-current and thermal protection. Bikes with a pedal assist function typically have a disc on the crank shaft featuring a ring of magnets coupled with a Hall sensor giving rise to a series of pulses, the frequency of which is proportional to pedaling speed. The controller uses pulse width modulation to regulate the power to the motor. Sometimes support is provided for regenerative braking but infrequent braking and the low mass of bicycles limits recovered energy. An implementation is described in an application note for a 200 W, 24 V Brushless DC (BLDC) motor.
Motor: We have a blog post showing some motor differences: https://www.ebikekit.com/blogs/news/its-whats-inside-your-motor-that-counts Cabling is probably the #1 issue when something goes wrong. Good connectors, good cables, and good assembly (bike shop!) are crucial Strain reliefs on all cable joints! Where you have a junction box or a connector, the stress is concentrated over a small area near this stiff spot on the cable. This can cause small breaks on the internal...
If you’re interested in an ebike, you have a couple of options: converting your existing bike or buying an electric version. Abadie says a bike suitable for conversion will have a powerful brake system, wider tires and a strong frame that can hold the motor and battery. He charges $800 to $1,200 to find the right parts and motors for a particular bike.
Sometimes space comes at the most premium of commodities and the Tern Vektron offers a space-saving folding option. At about $3,400, the sturdy folding joints include a magnet and rubber strap to keep the bike folded. The quick-release pedals (wheels release too) help with storage of a bike that doesn’t give up power with a 20-mph speed that can range over 60 miles. But the best part is placing two in the trunk of a car.
But this bike isn’t just about the accessories. The powerful 48V 13Ah battery will allow you to pedal for longer, with some riders getting over 100 miles from one charge. The bike can be ridden as pedal-assist or throttle only and it’s equipped with full suspension and puncture-free Kenda tires. It folds up neatly to fit into the boot of a car or for commuting, though at 57 pounds, it’s heavy to cart around. A great value-for-money commuting bike with lots of features.
For many bikes, battery range is more important that total power (because they're all pretty powerful). You want a bike that delivers a range long enough for your rides at the power levels you want. Most e-bikes will have three to five levels of assist kicking in anywhere from 25 percent of you pedal power to 200 percent boost. Consider how fast the battery takes to recharge, especially if you'll be using your bike for long commutes.