In a friction drive motor, a small, solid wheel rotates against the side of the tire in order to drive it. The first motorcycles used the same concept, with a motor mounted above the front wheel. The problem is that the drive rubs at the side of the tire. It's inefficient, and it quickly wears the sidewall away. Tires need to be replaced every couple hundred miles. For this reason, you'll seldom see electric bikes with this type of drive anymore.

Some components, which are often optional accessories on sports bicycles, are standard features on utility bicycles to enhance their usefulness, comfort, safety and visibility. Mudguards, or fenders, protect the cyclist and moving parts from spray when riding through wet areas and chainguards protect clothes from oil on the chain while preventing clothing from being caught between the chain and crankset teeth. Kick stands keep bicycles upright when parked, and bike locks deter theft. Front-mounted baskets, front or rear luggage carriers or racks, and panniers mounted above either or both wheels can be used to carry equipment or cargo. Pegs can be fastened to one, or both of the wheel hubs to either help the rider perform certain tricks, or allow a place for extra riders to stand, or rest.[citation needed] Parents sometimes add rear-mounted child seats, an auxiliary saddle fitted to the crossbar, or both to transport children. Training wheels are sometimes used when learning to ride.

Whether the terrain is flat or hilly impacts the distance you can travel, as does the weight of the bike, your own weight, the gearing available on the bike, and how much juice you give it. We suggest that a distance of 10 to 20 miles is a realistic expectation. Of course, if you're prepared to do at least some pedaling, you can extend that dramatically.
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]
I had gotten this to build an electric bike but I have never worked with wires before so I didn't realize that we needed to attach our own connectors to the wires. The person who I talked to at Joyisi was super nice and explained that to me and even offered to send me connectors for free. I had already ended up getting a different bike altogether though and so I just wanted to return the battery. But because I am returning it for my own reasons (as opposed to the battery being faulty), they would normally have me pay for return shipping and deduct the cost of shipping to me (which is a lot, because they are international) and the inspection fee from my refund, but they were super nice and offered to take on most of the costs and I would only have to pay for the return
But the whole is also influenced by the sensory systems which are very different from model to model. E.g. A typical 2013 Panasonic system requires pedalling for optimal support (55/minute?) and has both a pedalling frequency and a speed sensor. You don't get much assistance if you pedal very slowly or very fast. Typically, a rear motor has a force sensor, i.e. you get lots of support fast when you start pedalling in a low gear, i.e. it will "feel" your need for assistance.
Track bicycles do not have brakes, because all riders ride in the same direction around a track which does not necessitate sharp deceleration. Track riders are still able to slow down because all track bicycles are fixed-gear, meaning that there is no freewheel. Without a freewheel, coasting is impossible, so when the rear wheel is moving, the cranks are moving. To slow down, the rider applies resistance to the pedals, acting as a braking system which can be as effective as a conventional rear wheel brake, but not as effective as a front wheel brake.[51]
Under the doctrine of One Country, Two Systems, Hong Kong has independent traffic law from mainland China. Electric bike are considered as motorcycles in Hong Kong, and therefore needs type approval from the Transport Department as other automobiles. All electric bike availble in Hong Kong fail to meet the type approval requirement, and Transport Department has never granted any type approval for electric bike, making all electric bike effectively illegal in Hong Kong. Even if they got type approved, the driver would need a motorcycle driving license to ride[14]. As a side note, Hong Kong doesn't have a moped vehicle class (and therefore moped driving license), and mopeds are consided as motorcycles too.
The $3,099 MSRP is a bit daunting if you've not shopped for high-end bikes before, but it compares favorably with, say, Trek's electric bike lineup. That said, you can get a solid urban/commuter bike without a motor for well under $1,000. You can even score an e-bike for under a grand, but you'll likely be looking at a battery range of less than 40 miles, along with lower-quality components.
eBikes are a key part of solution to reduce carbon emissions globally. The Zero-emission part of the eBike discussion is based on re-charging the battery on a daily basis from a Sustainable Electrical Source such as solar, wind, hydro, geo thermal, etc.  The fact is today part of the eBike Battery charge is coming from Power Plants that are running …
The federal law will not prohibit a motor vehicle label and additional restrictions given by the state. States will typically define e-mopeds in the 1000W range (1.5 hp) and speeds attainable to 30mph, and include a few requirements such as a helmet, eye protection, and a driver’s license. States may also require title, registration, and insurance for mopeds.
Even the humble bicycle hasn't escaped the clutches of modern technology. A whole herd of new e-bikes with electric motors are taking to our cities' streets. Adding a motor to a standard cycle does ramp up the price significantly, but it takes much of the effort out of cycling, making your commute to the office a sweat-free experience and allowing you to sit back and enjoy your suburban cruise.
In Norway, e-bikes are classified as ordinary bicycles, according to the Vehicle Regulation (kjøretøyforskriften) § 4-1, 5g. Hence, e-bikes are not registered in the Vehicle Registry, and there is no demand for a license to drive them. Still, there are constraints on the bicycle construction. The maximum nominal motor power output can be no more than 250 watts and the maximum performance speed of the vehicle when the engine is running is 25 km per hour (15 mph).[40] A function that reduces motor power when vehicle speed exceeds 25 km per hour is mandatory. However, if the motor is not running, the e-bike, or any other bike, answer only to the constraints of the ordinary speed limits. 

The federal law will not prohibit a motor vehicle label and additional restrictions given by the state. States will typically define e-mopeds in the 1000W range (1.5 hp) and speeds attainable to 30mph, and include a few requirements such as a helmet, eye protection, and a driver’s license. States may also require title, registration, and insurance for mopeds.

Some US companies, notably in the tech sector, are developing both innovative cycle designs and cycle-friendliness in the workplace. Foursquare, whose CEO Dennis Crowley "pedaled to pitch meetings ... [when he] was raising money from venture capitalists" on a two-wheeler, chose a new location for its New York headquarters "based on where biking would be easy". Parking in the office was also integral to HQ planning. Mitchell Moss, who runs the Rudin Center for Transportation Policy & Management at New York University, said in 2012: "Biking has become the mode of choice for the educated high tech worker".[66]