Torque sensors and power controls were developed in the late 1990s. For example, Takada Yutky of Japan filed a patent in 1997 for such a device. In 1992 Vector Services Limited offered and sold an e-bike dubbed Zike.[9] The bicycle included NiCd batteries that were built into a frame member and included an 850 g permanent-magnet motor. Despite the Zike, in 1992 hardly any commercial e-bikes were available.
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.[43]
Thousands of people have discovered the electric bike smile just by trying out an electric pedal assist bike. So this year Subaru VeloSwap has partnered with the Colorado Electric Bikes Expo sponsored by BEST electric bike USA. There will be an entire area just dedicated to showcasing electric bikes. You can view and experience the latest brands, styles, and new  technology in the world of electric bikes.  Reps will be available to show you how they work &  answer questions. This is a great opportunity for you to see, and learn about, and even ride all the top brands of electric bikes.   On hand will be brands like PEDEGO, EASY MOTION, HAIBIKE, RIESE & MULLER, MAGNUM, STROMER, BOSCH, YAMAHA,...
Electric bikes are categorized by classes: Class 1 ebikes are pedal-assist cycles with a top speed of 20 mph. (Some localities have banned Class 2 and Class 3 ebikes, which are throttle on demand.) The trick to using a Class 1 bike is to, well, pedal. “If the pedals stop, the bike doesn’t go,” says Saltvold, who describes using an ebike as akin to running on a moving walkway in an airport terminal. Whitaker notes that customers say they switch off the pedal-assist to get more exercise, then turn it back on when going up a hill or wanting to increase their speed.
After you decide which style of e-bike you want, consider the class. In the US, there are three classes defined by the type of assist and how fast the motor will propel you. Most electric bikes sold are class 1 or 3. Class 1 bikes have a motor (max 750w) that assists while you're pedaling, up to 20 mph. Class 3, also known as “speed pedelec” can also have up to a 750w motor, but it can assist you up to 28mph. Both of those are allowed in most states and cities without license. Class 2 have throttles that don't require you to pedal to get a boost. They're allowed on most streets, bike lanes, and paths, but less popular than the other classes and not covered much here (because we still love to pedal and the greater distances pedal assist bikes can cover).