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]
Is it worth $1700? I’ll let you be the judge. I don’t have a lot of experience with commuter ebikes so I don’t know how it compares. I do know that most of the ebike conversions I’ve seen look like science experiments. The Buffalo could pass for a normal bike, and look a little more accessible to a first time ebike user. So, although I’m not planning on riding this, I am planning on using it. So I’ll keep it around for a while and let you guys know what I think long term.
We ran the C330 almost entirely in its speediest Turbo setting, switching back to Eco or Tour in heavy traffic for a more predictable assistance weaving between cars. Crucially, the display also displays how much assistance you’re getting as well as your speed, trip distance, etc. We used this to ease-back effort and stay in a light power sweet-spot, arriving at WIRED’s HQ without breaking a sweat.

Comfort. Like any other type of bike the electric bike should offer you a comfortable ride. All general components such as, saddle, handlebars, the geometry of the frame should put you in a comfortable position. If the bike doesn’t satisfy these criteria it’s certainly not the best electric bike on the market. After all you’re going to spend quite a lot of time riding it, so you might as well look for a more comfortable solution.

Thank you Clean Republic for coming to my rescue when I had a battery issue last year. Under Warranty at 11.5 months, they without hesitation sent me an entire new $355 Battery pack when mine began to fail. I've gotten so much life, miles, and usage out of my Hill Topper from this first one and am about to replace the batteries again from so much more love on them. Seems the hub motor is going to last forever and that's what counts! Thanks guys! :)
{"id":1475554639938,"title":"SONDORS Fold Sport (NOVEMBER SHIPPING)","handle":"sondors-fold-sport-shipping-nov18","description":"","published_at":"2018-01-22T06:00:00-08:00","created_at":"2018-07-27T11:26:22-07:00","vendor":"SONDORS Electric Bikes","type":"Electric Bike","tags":["Battery","bike","folding bike","gear","ion","lithium","motor","shimano","sondors","SONDORS Fold","sondors folding bike","tire"],"price":99900,"price_min":99900,"price_max":99900,"available":true,"price_varies":false,"compare_at_price":null,"compare_at_price_min":0,"compare_at_price_max":0,"compare_at_price_varies":false,"variants":[{"id":12819691798594,"title":"Navy","option1":"Navy","option2":null,"option3":null,"sku":"186","requires_shipping":true,"taxable":true,"featured_image":{"id":3973565022274,"product_id":1475554639938,"position":1,"created_at":"2018-08-02T12:53:18-07:00","updated_at":"2018-08-06T05:24:29-07:00","alt":"SONDORS Fold Sport (NOVEMBER SHIPPING) - SONDORS Electric Bikes","width":1023,"height":660,"src":"https:\/\/\/s\/files\/1\/1439\/6088\/products\/NAVY.jpg?v=1533558269","variant_ids":[12819691798594]},"available":true,"name":"SONDORS Fold Sport (NOVEMBER SHIPPING) - Navy","public_title":"Navy","options":["Navy"],"price":99900,"weight":136078,"compare_at_price":null,"inventory_quantity":1,"inventory_management":"shopify","inventory_policy":"deny","barcode":""},{"id":12819691831362,"title":"Black","option1":"Black","option2":null,"option3":null,"sku":"184","requires_shipping":true,"taxable":true,"featured_image":{"id":3973564825666,"product_id":1475554639938,"position":3,"created_at":"2018-08-02T12:53:17-07:00","updated_at":"2018-08-06T05:24:29-07:00","alt":"SONDORS Fold Sport (NOVEMBER SHIPPING) - SONDORS Electric Bikes","width":1023,"height":660,"src":"https:\/\/\/s\/files\/1\/1439\/6088\/products\/BLACK.jpg?v=1533558269","variant_ids":[12819691831362]},"available":true,"name":"SONDORS Fold Sport (NOVEMBER SHIPPING) - Black","public_title":"Black","options":["Black"],"price":99900,"weight":136078,"compare_at_price":null,"inventory_quantity":5,"inventory_management":"shopify","inventory_policy":"deny","barcode":""},{"id":12819691864130,"title":"Silver","option1":"Silver","option2":null,"option3":null,"sku":"185","requires_shipping":true,"taxable":true,"featured_image":{"id":3973565120578,"product_id":1475554639938,"position":2,"created_at":"2018-08-02T12:53:19-07:00","updated_at":"2018-08-06T05:24:29-07:00","alt":"SONDORS Fold Sport (NOVEMBER SHIPPING) - SONDORS Electric Bikes","width":1023,"height":660,"src":"https:\/\/\/s\/files\/1\/1439\/6088\/products\/SILVER.jpg?v=1533558269","variant_ids":[12819691864130]},"available":true,"name":"SONDORS Fold Sport (NOVEMBER SHIPPING) - Silver","public_title":"Silver","options":["Silver"],"price":99900,"weight":136078,"compare_at_price":null,"inventory_quantity":12,"inventory_management":"shopify","inventory_policy":"deny","barcode":""}],"images":["\/\/\/s\/files\/1\/1439\/6088\/products\/NAVY.jpg?v=1533558269","\/\/\/s\/files\/1\/1439\/6088\/products\/SILVER.jpg?v=1533558269","\/\/\/s\/files\/1\/1439\/6088\/products\/BLACK.jpg?v=1533558269"],"featured_image":"\/\/\/s\/files\/1\/1439\/6088\/products\/NAVY.jpg?v=1533558269","options":["Color"],"content":""}
Yes, you read that right – north of £4k for a bike. But then, this is basically the top end of the mountain e-bike market, and you do get a lot of bike for your buck: a Yamaha Lithium battery, masterful Magura brakes, mud-slaying tyres, and – my favourite flourish of all – a hydraulic seat post that you can adjust on the move (surprisingly useful when navigating tricky downhill trails, as it means you can depress the saddle out of the way with the press of a button). 
Although ebikes are easier to use in some instances, such as climbing hills, there are safety concerns. Because the bikes are heavier than traditional bikes, balance can be a problem. And, of course, ebikes allow people to cycle at higher speeds than usual. “A normal rider will average between 12 to 15 mph, where an ebike rider will average between 15 to 20 mph,” Abadie says. An increase in the number of deaths of elderly male ebike riders in the Netherlands has been attributed to their overconfidence in being able to ride at high speeds and to mount and dismount the bikes.
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.

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.
Fat E-Trike from Sun and E-BikeKit™ at Interbike 2014 Fat bikes and electric bikes were all the rage this year at interbike in Las Vegas. It seemed almost every bike vendor at the show has at least one fat bike model in their booth this year. On top of the fats were the electric bikes. And I think it goes without saying that nobody wants to actually pedal a fat...
It will be of little surprise to learn that the Hanebrink all-terrain vehicle was designed by six time Mountain Bike national class champion and former U.S. National Team member Dan Hanebrink. It's based on 1993's Extreme Terrain fat tire pedal bike and is made to order at the Fortune Hanebrink workshop at Big Bear Lake, California. Echoing the philosophy of many electric assist bicycle makers, Hanebrink says: "We are not trying to replace standard bicycles, we want to replace cars and trucks."
The riding position is racy, and we suffered a numb left hand after 45 minutes of riding due to a combination of the Bullhorn bars and the narrow position adopted to cover the ‘sissy’ brakes in traffic (picking a flat bar model would be more practical for city commuting). The biggest drawback to the Soho is that on a single-speed the 15.5mph cut-off (for all e-bike motors in Europe) left us feeling like we’d been "deserted". Over the cut-off speed we found ourselves dragging that heavy back wheel with no alternate gears to reach for.

The Patriot DreamE results from the combination of the popular Day 6 bicycle with the Kinetic8-Fun mid-drive motor kit. The unique Day 6 styling eliminates leaning forward, so you sit perfectly upright. That means there is no more stress on wrists, neck, back, and crotch. It also means a superior breathing position and a better way to enjoy the scenery. The step-through design makes for easy mounts and dismounts, while the low seat allows the rider to reach the ground with both feet for stability and safety.

To be honest, this bike is really designed for city commuters or kids riding around the suburbs. The fact that it’s foldable will let you carry it on the bus, on the train or even on the plane. It’s just not designed for heavy riding, long distances or tough terrains. If you want something sleek and fabulous at a fraction of the cost of most other e-bikes, this baby’s for you.
Because e-bikes are capable of greater speeds for longer periods of time than standard bikes, you want extra control. Wider tires provide traction and some bump absorption with little penalty. You also want strong brakes to slow you (and all that extra weight) easily. It's worth looking at the quality of the brakes and investing in bikes with better ones if you can.