It appears Tennessee has not passed any legislation that applies to electric bicycles. Some people think the laws pertaining to a Motorized Bicycle should be used for an electric bicycle. However, a Motorized bicycle would be a gasoline powered device per state law as it is defined as "means a vehicle with two (2) or three (3) wheels, an automatic transmission, and a motor with a cylinder capacity not exceeding fifty cubic centimeters (50cc) which produces no more than two (2) brake horsepower and is capable of propelling the vehicle at a maximum design speed of no more than thirty miles per hour (30 mph) on level ground." 
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.
There are two basic categories of electric bike, and their uses don't offer equal crossover value. The first category is essentially a normal bicycle that has been outfitted with an electric motor. These bikes are the same size as a standard bicycle, and handle almost identically, save for the obvious benefit of added motive power thanks to a motor and battery.
The first functioning electric motor was displayed in the early 19th century, though the device constructed by British scientist Michael Faraday did little more than swirl a wire around a magnet when an electric charge was introduced. Still, the concept proved that electricity could do work. Functional electric motors would follow in many forms after that achievement in 1821. Soon scientists and tinkerers around the world, including visionaries such as Nikola Tesla, were experimenting with all manner of electric motors -- some worked with DC power, others with AC. By the end of the century, myriad electric motors had been produced, capable of exerting enough force with enough reliable control that they were practical for use in myriad applications.
In Australia the e-bike is defined by the Australian Vehicle Standards as a bicycle that has an auxiliary motor with a maximum power output not exceeding 200 W without consideration for speed limits or pedal sensors. Each state is responsible for deciding how to treat such a vehicle and currently all states agree that such a vehicle does not require licensing or registration. Various groups are lobbying for an increase in this low limit to encourage more widespread use of e-bikes to assist in mobility, health benefits and to reduce congestion, pollution and road danger. Some states have their own rules such as no riding under electric power on bike paths and through built up areas so riders should view the state laws regarding their use. There is no licence and no registration required for e-bike usage.
Different gears and ranges of gears are appropriate for different people and styles of cycling. Multi-speed bicycles allow gear selection to suit the circumstances: a cyclist could use a high gear when cycling downhill, a medium gear when cycling on a flat road, and a low gear when cycling uphill. In a lower gear every turn of the pedals leads to fewer rotations of the rear wheel. This allows the energy required to move the same distance to be distributed over more pedal turns, reducing fatigue when riding uphill, with a heavy load, or against strong winds. A higher gear allows a cyclist to make fewer pedal turns to maintain a given speed, but with more effort per turn of the pedals.
I discovered these downsides when, on my third day with the bike, I got a flat tire and had to carry it onto the subway with me for those last few miles back to my apartment. The cause of the flat is unknown; the bike mechanic who eventually fixed it didn’t see anything wrong with the rims. But the experience of trying to maneuver an almost 40 pound e-bike on and off a crowded subway car during rush-hour is not one I can recommend.
Electric bikes are a green alternative to driving a vehicle. Studies carried out in several towns and cities show that the average car speed in rush hour traffic can dip as low as 18 to 20 mph. Electric bike speed can be as high as 15 mph. With an electric bike, you can reduce pollution, improve fitness, and still arrive at the same time as your car-bound colleagues.
We've also released our first native 72V battery pack in a conventional downtube battery casing, assembled using the high power Samsung 27100 40T cells so that even with the small 8Ah capacity it is able to deliver 40-50A continuous currents. This is an ideal battery for fast and sporty offroad ebike builds, allowing powerful performance without the weight or complexity of most 72V setups (either two 36V packs in series or a large triangle frame battery).
Firstly there's a magnetically-fired locking pin in the rear wheel, triggered by kicking a button on the hub. This is fairly secure in itself and almost impossible to remove without destroying the bike. In London, we'd pair it with a more traditional bike lock so there's a more obvious visual deterrent, though a LED matrix screen on the frame does issue a warning to would-be tea-leafs.
A new European product safety standard EN 15194 will be published in 2009. EN 15194 contains several new requirements for ebikes to be sold in European Union and European Economic Area, including weight and voltage limitations. EN 15194 also defines a specific name for EU approved electrically-assisted cycles, EPAC - "Electrically Pedal Assisted Cycle".
In the 1890s, electric bicycles were documented within various U.S. patents. For example, on 31 December 1895, Ogden Bolton Jr. was granted U.S. Patent 552,271 for a battery-powered bicycle with "6-pole brush-and-commutator direct current (DC) hub motor mounted in the rear wheel". There were no gears and the motor could draw up to 100 amperes (A) from a 10-volt battery.
The are no ADRs applicable to AA or AB category vehicles. There are ADRs for lighting, braking, noise, controls and dimensions for LA category vehicles, mostly referencing the equivalent UN ECE Regulations. An approval is required to supply to the market any road vehicle to which ADRs apply and an import approval is required to import any road vehicle into Australia.
You are not allowed to drive S-Pedelecs in France even if they are registered legally in your country (e.g. Germany or Switzerland). In other words, if you plan to take your 45h bike that is legal in your country on vacation in another where it is not, you may violate traffic law. Remove the license plate or don't do it. People who commute between countries, are known to hack removable plates with magnets ...
Simple, convenient, cheap, and economical—bicycles are one of the world's favorite forms of transportation. But they're not for everyone. They can be hard to pedal up and down hills or with heavy loads, and elderly or disabled people may find them impossible to manage. In the last few years, a new generation of electric bicycles has begun to revolutionize our idea of environmentally friendly transportation. These new cycles have all the convenience of cars with all the simple economy of ordinary cycles. Let's take a closer look at how they work.