Controllers for brushed motors: Brushed motors are also used in e-bikes but are becoming less common due to their intrinsic lower efficiency. Controllers for brushed motors however are much simpler and cheaper due to the fact they don't require hall sensor feedback and are typically designed to be open-loop controllers. Some controllers can handle multiple voltages.
“At $500 apiece,” he says, “the company would be selling e-bikes at a loss, once they factored in product liability insurance, quality control, regulatory compliance, safety testing, and post-sales service and support. Chinese e-bikes could certainly ‘leak’ into the U.S. market near that cost, be sold as a loss leader, or be marketed directly on eBay, but a fully costed business model could potentially lose up to $250 per bike.”

The frame itself incorporates a series of mounts allowing you to easily trick-out the Road E+1 with a rack, fenders, or panniers to more aptly meet your touring requirements. Again, most touring purists will certainly scoff at the mere notion of pedal-assistance, however, individuals looking for more of a guided tour and less of a tour de force will swoon over the Road E+1.

Rachel L. Davis is an avid bicyclist. But as a working mother of two, with a third child on the way, she doesn’t have time for long bike rides. “In my world, getting my exercise has to be part of my daily life,” says Davis, 36, who owns a marketing strategy company based in Washington. “I live in a hilly part of D.C., and as I’ve become more pregnant, more tired with more children, I don’t have as much energy to be biking 40 miles or biking to Alexandria.”

Folding Electric Bikes- These are mostly used when people need to combine different modes of transport. For example, if you need first to take the train or bus, a folding e-bike can be useful to carry along. Also, very short trips are more convenient with these electric bikes since you don’t need to bother tying them up. Typically, these are very light, even with the motor and battery.

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.
Unlike most e-bikes, the Brompton's battery is integrated into a bag that sits on the front of the bike. While that detracts slightly from the classic, streamlined design, it's handy as it can be unclipped for charging or riding as a regular bike – it's probably one of the easiest to ride without battery assistance thanks to its weight. The battery also powers two lights for safe commuting. 
Most consumers want an e-bike that will accommodate its motor without being too cumbersome and will remain stable in spite of its electronic components. Some consumers want only the most basic of e-bike features, including lights, a cargo rack/basket, and a water bottle holder. Others are focused more heavily on safety features, such as brake type. And still others are concerned with convenience and portability.

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]

The Cyrusher doesn’t have the reliable Bosch motor that higher-end bikes sport and the Samsung battery is only good for around 500 recharges, which is less than you’d expect for a lithium battery. But with the low price point, there are bound to be some compromises. A great option if you want a decent, all-around model for easy trails or commuting.
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.
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.