On the road, it takes only a few turns of the pedals to activate the Vado’s motor and get it up to speed. In Turbo mode — the bike’s highest level of pedal-assist — the Vado reaches speeds of up to 28 miles per hour, after which the electric drive system automatically shuts off to conserve power (and abide by local law). A built-in LED readout on the handlebars allows riders to monitor battery life, check current speed, and track calories burned while also being able to glance at distance traveled. The Turbo Vado Mission Control app (iOS/Android) also connects to the bike via Bluetooth and allows riders to further tune their ride and adjust the bike’s settings.
Bicycle manufacturing proved to be a training ground for other industries and led to the development of advanced metalworking techniques, both for the frames themselves and for special components such as ball bearings, washers, and sprockets. These techniques later enabled skilled metalworkers and mechanics to develop the components used in early automobiles and aircraft.
Earlier UK regulations required that the motor has an average power output limited to 200 W (250 W for tricycles and tandems) and weight limited to 40 kg (60 kg for tricycles and tandems). These regulations must come in-line with the EU regulations by (find deadline). For models sold before June 2003, e-bikes conforming to the speed, weight and power limits may also be considered pedal cycles. Electric bikes with higher power outputs, or those not meeting the "pedelec" definition are now treated as motorcycles and require a license.
I purchased version 2.0 of this device and the manufacturer has been listening to comments from users and making running changes such as the three speeds and the rear suspension. I am an XL size user (6'2", 230lbs) and recently returned from a 26 day cruise around Europe. I rode this little scooter on cobblestones, miles and miles through the Vatican, inside ancient cities and all over the streets of San Juan upon our return stateside. There was only one time it was less than ideal and that was going uphill, on slick tile that was wet from a drizzle. It still make it, just had to lean way forward to get weight on the front wheel.
There are individuals who claim to have lost considerable amounts of weight by using an electric bike. A recent prospective cohort study however found that people using e-bikes have a higher BMI. By making the biking terrain less of an issue, people who wouldn't otherwise consider biking can use the electric assistance when needed and otherwise pedal as they are able. This means people of lower fitness levels or who haven't cycled in many years can start enjoying the many health benefits E-bikes have to offer. 
Artwork: Hub motors aren't the only way to power electric bicycle wheels. If you've ever watched a mouse scampering around inside an exercise wheel, you might have wondered if you could drive a wheel electrically, in a similar way, with something that pushes against the inside of the rim. A company called GeoOrbital has been developing an ingenious mechanical equivalent that can be used to power conventional bikes—and here's a simplified illustration of how it works. It has a motorized drive roller (red) that presses against the inner rim, powered by a battery pack (orange) that sits snugly inside the wheel. Two guide rollers (blue) mounted on a tensioned framework (green) take the place of the conventional arrangement of spokes. According to GeoOrbital, you can fit one of its wheels to a normal bike in just 60 seconds.
Electric bikes are considered motorcycles in Hong Kong, and therefore need type approval from the Transport Department, just as automobiles. All electric bikes available in Hong Kong fail to meet the type approval requirement, and the Transport Department has never granted any type approval for an electric bike, making all electric bikes effectively illegal in Hong Kong. Even if they got type approval, the driver would need a motorcycle driving license to ride. As a side note, Hong Kong doesn't have a moped vehicle class (and therefore no moped driving license), and mopeds are considered motorcycles too.
Louisiana Revised Statute R.S. 32:1(41) defines a motorized bicycle as a pedal bicycle which may be propelled by human power or helper motor, or by both, with a motor rated no more than one and one-half brake horsepower, a cylinder capacity not exceeding fifty cubic centimeters, an automatic transmission, and which produces a maximum design speed of no more than twenty-five miles per hour on a flat surface. Motorized bicycles falling within this definition must be registered and titled under Louisiana law. Additionally, a motorized bicycle operated upon Louisiana roadways or highways by a person fifteen years of age or older and producing more than five horsepower must possess a valid driver's license with a motorcycle endorsement and adhere to laws governing the operation of a motorcycle, including the wearing of approved eye protectors or a windshield and the wearing of a helmet. The statute also states that "Motorized bicycles such as pocket bikes and scooters that do not meet the requirements of this policy shall not be registered."
My homeowners (State Farm) covers bikes , but assumes $500 per bike. They will add the bikes as personal property, but the premium is excessive (about $300/year per bike, and we have four bikes). I did increase our personal umbrella liability coverage, and it covers us if family members any sort of accident on our e-bikes that injures us or others or others' property, though only covers $500 each for our own bikes (under the homeowners coverage). It was not very expensive to increase the umbrella policy (as it resulted also in a reduced rate on our car insurance).
The oldest patent for an electric bike I've been able to find at the US Patent and Trademark Office is this one, by Ogden Bolton, Jr. of Canton Ohio, which was filed in September 1895 and granted three months later. You can see from these original diagrams that it bears an amazingly close resemblance to modern electric bikes. In the general picture on the left, you can see there's a hub motor on the rear wheel (blue), a battery suspended from the frame (red), and a simple handlebar control to make the thing stop and go. In the more detailed cutaway of the hub motor on the right, you can see there's a six-pole magnet in the center (orange) bolted to the frame and an armature (made from coiled wire, yellow) that rotates around it when the current is switched on. It's quite a hefty motor even by modern standards; Ogdon mentions "a heavy current at low voltage—for instance, to carry one hundred amperes at ten volts." So that's 1000 watts, which is about twice the power of a typical modern bike hub motor.
Great question… a real world situation from someone doing their best to follow the law but also be realistic about time/distance. What follows is my opinion on the matter based on lots of electric bike riding experience, this is not legal advice. You can probably ride with electric assist across the dirt way with no issues and avoid any negative response that might arise as long as you’re polite to other cyclists and pedestrians and pedal along without going too fast. If someone called you out about it you could easily hop off, walk your bike and explain that you use the assist to help make your commute possible or possibly, like me, you have a knee injury and it’s difficult to pedal through softer terrain like gravel. Another different approach might be to shut the bike off completely before entering the gravel section, you could even take the battery off and put it in a backpack or as mentioned earlier… just walk the bike. Imagine if you had a motorized dirt bike and were just pushing it along a sidewalk… this kind of vehicle definitely is not allowed on sidewalks or most gravel paths like the one you’re describing but if you were escorting it carefully, you’d be honoring the spirit of the law and if an officer or pedestrian jumped out and started questioning you about your “motorized vehicle” it is my feeling that a genuine explanation and apology or request for guidance would go very well. I personally have never had issues riding electric bikes in part because I am thoughtful about how I use them. I do occasionally switch them off and sometimes I get off and walk. I have asked police in many cities across the US what they thought about ebikes and in every case I have received positive interest and support with guidance to ride safe with a helmet and follow traffic laws in the street. I hope this helps and I wish you well, it’s nice that you care enough to ask and I hope you’re treated well by others out on the road. The flip side of this response is that I have been harassed, yelled at and even swerved at by automobiles when riding bicycles and electric bikes. This usually happens in the evening after work lets out when traffic is heavy and I’m riding on the shoulder or in the street (where marked to do so) and I believe it has to do with territory, testosterone and socio-economic standing more so than laws or anything like that.
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.
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 electric bicycle dubbed Zike. The bicycle included Nickel-cadmium batteries that were built into a frame member and included an 850 g permanent-magnet motor. Despite the Zike, in 1992 hardly any commercial electric bicycles were available. It wasn’t until 1998 when there were at least 49 different bikes. Production grew from 1993 to 2004 by an estimated 35%. By Contrast, according to Gardner, in 1995 regular bicycle production decreased from its peak 107 million units. Some of the less expensive electric bicycles used bulky lead acid batteries, whereas newer models generally used NiMH, NiCd and/or Li-ion batteries which offered lighter, denser capacity batteries. The end benefits usually varied from manufacturer; however, in general there was an increase in range and speed. By 2004 electric bicycles where manufactured by Currie Technologies, EV Global, Optibike, Giante Lite, Merida, ZAP.
EU: EN15194 (EPAC – Electrically Power Assisted Cycles) defines the use pedal-assisted less than 25k/h bikes: "Cycles with pedal assistance which are equipped with an auxiliary electric motor having a maximum continuous rated power of 0.25 kW, of which the output is progressively reduced and finally cut off as the vehicle reaches a speed of 25 km/h or if the cyclist stops pedaling.”
There are two main categories when choosing an e-bike: a pre-built electric bike or a custom e-bike conversion. Prefab electric bikes come in a wide variety of setups and styles and are designed specifically as electric bicycles. With unique characteristics and design qualities, most meet the law requirements which limit power and speed. There is also a variety of options to choose from equipped with different design and different motor and battery configurations to suit different riding styles and preferences: cruisers, commuters, mountain bikes and more. Pre-built e-bikes are clean and sleek in design with all of the wiring and electrical components built directly into the bike. For most people, production e-bikes work great and there’s no need for a custom conversion.
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). 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.