The bicycle is extraordinarily efficient in both biological and mechanical terms. The bicycle is the most efficient human-powered means of transportation in terms of energy a person must expend to travel a given distance. From a mechanical viewpoint, up to 99% of the energy delivered by the rider into the pedals is transmitted to the wheels, although the use of gearing mechanisms may reduce this by 10–15%. In terms of the ratio of cargo weight a bicycle can carry to total weight, it is also an efficient means of cargo transportation.
In cities where bicycles are not integrated into the public transportation system, commuters often use bicycles as elements of a mixed-mode commute, where the bike is used to travel to and from train stations or other forms of rapid transit. Some students who commute several miles drive a car from home to a campus parking lot, then ride a bicycle to class. Folding bicycles are useful in these scenarios, as they are less cumbersome when carried aboard. Los Angeles removed a small amount of seating on some trains to make more room for bicycles and wheel chairs.
Because the power is applied through the chain and sprocket, power is typically limited to around 250–500 watts to protect against fast wear on the drivetrain. An electric mid-drive combined with an internal gear hub at the back hub may require care due to the lack of a clutch mechanism to soften the shock to the gears at the moment of re-engagement. A continuously variable transmission or a fully automatic internal gear hub may reduce the shocks due to the viscosity of oils used for liquid coupling instead of the mechanical couplings of the conventional internal gear hubs.
So first off, it isn’t fair to compare the power of a Chinese rear hub motor watt for watt with a 250W Bosch or Brose or even a Shimano or Yamaha mid-drive motor. There just isn’t even close to the amount of torque or power on a per watt basis and that’s before we get to controllers. However, comparing the Rattan’s 350W motor to the Ancheer’s 250W motor seems more proportionally correct. Where as I could make it about a third of the way up my driveway hill from a cold start on Ancheer throttle, I made it about 2/3rds of the way with the Rattan, or another 100 feet. On a flat surface, again with throttle only, I hit 20 mph in about 10 seconds with the Rattan. It takes me another 5+ seconds to get there on the Ancheer. One note, the battery gauge does bounce around a bit depending on how much it is working. At full throttle you might lose a bar or 2 only to get it back once you coast.
But the good times of the stealthy ebike existence will not endure forever. The ebike market is growing steadily and more so, technology is driving performance up and costs down. The market for a green, lifestyle friendly, transportation technology, with GPS, theft ID, cell service and probably skim lattes is alive and driving an emerging market. It is a matter of time before we all must face and respond to the legal demands of the state and local laws. Not to be over obligatory about being legal and duty oriented, but I do call on my fellow ebikers to ride legal, whether ebike, moped or other. Go ahead and build the 1200W ebike of your dreams, but get it insured and licensed if you must. Such compliance will set the precedence for public acceptance of ebikes in general, and build a track record for expansion and mainstreaming of moped-speed ebikes for commuter value driven needs of the future.
Ebike definition in Colorado follows the HR 727 National Law: Template:Convert e-power and Template:Convert max, 2 or 3 wheels, pedals that work. Legal low powered Ebikes are allowed on roads and bike lanes unless the city or county has passed laws to the contrary (Boulder city bans ebikes over 400W from bike lanes and all ebikes from bike paths) -none -(except Boulder city) have to date. Bicycles and Ebikes are disallowed on certain high speed highways and all Interstates unless signed as "Allowed" in certain rural Interstate stretches where the Interstate is the ONLY means of travel.  Unless the locality has specifically passed laws making ebikes illegal on sidewalks or trails, Ebikes are legal. However most business and shopping districts do not allow riding bikes or ebikes on sidewalks. Boulder and a few other cities specifically dis-allow ebikes on their trail systems through legal statute.
Electric bicycles are considered as "bicycles" under Montana law as the law defines bicycles in a two part definition where the first part of the definition describes a conventional bicycle propelled solely by human power and the second part of the definition describes a bicycle equipped with an independent power source for propulsion in addition to foot pedals to permit muscular propulsion. (Montana Code 61-8-102).
But in Great Britain, the European Union definition is applicable, and the tighter restrictions of the Electrically Assisted Pedal Cycle Regulations 1983 (including a 200 kg weight limit on solo bicycles) were removed on 6 April 2015 by the Electrically Assisted Pedal Cycles (Amendment) Regulations 2015. Riders must be at least 14 years of age, but no driving licence is required.
"Medical Exemptions" are also a standard right in the State of Texas for motorcycles & even bicyclists. Through Texas's motorcycle helmet law (bicycle helmet laws from city ordinances), it is only required for those 21 years old or younger to wear a helmet. However, a medical exemption, written by a certified licensed medical physician or licensed chiropractor, which exempts one from wearing a helmet, can be used for bicyclists if helmets are required.
Both the Stromer and the Stoeckli are very nice looking designs and easy to handle. Reliability for both does not seem to be up to Swiss standards, e.g. some of the 2012 Stöcklis seem to have bad contacts. However, as of 2013, most of these problems should be fixed. The Cube got criticized for its battery/saddle system, but this has probably been fixed in more recent edition and it has less "punch" then the other's since the motor is smaller (324W?). I don't know about the BH Neo Nitro. Given the relatively low price of the BH Nitro, it may be the best buy in this category if you plan to cover smaller distances (the battery is limited to 9Ah, and Spain's industry does need some help ;) Anyhow, all of these models come with a variety of motors and country-specific modifications. E.g. in France, the BH Nitro comes with a 350W motor and is electronically limited to 25km/h, whereas in Switzerland you either can get a 500W - 45 km/h version or a 250W? - 25km/h version.
This Class 3 (28 mph), utilitarian, road e-bike is smooth and torquey thanks to its Bosch Performance Speed motor. With a drop bar and traditional road-bike position and handling, the CrossRip+ is more suited to longer rides on mixed terrain than navigating congested city streets. It comes with a rear rack—for mounting bags, not for attaching cargo directly—full fenders, a kickstand, and integrated front and rear lights (which are powered by a Bosch 500Wh battery). It features a SRAM Force 1x11 drivetrain, hydraulic disc brakes, and wide 700x38mm tires.
None of this would matter if the VanMoof Electrified S2 (and its close relative the X2) wasn't fun to ride, but it is a blast. Like the Brompton, it pulls off the neat trick of powering you along but giving the illusion that you're doing the work, reacting quickly and cleverly to the speed of your pedalling and the difficulty of any incline you're on.
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.
The drivetrain begins with pedals which rotate the cranks, which are held in axis by the bottom bracket. Most bicycles use a chain to transmit power to the rear wheel. A very small number of bicycles use a shaft drive to transmit power, or special belts. Hydraulic bicycle transmissions have been built, but they are currently inefficient and complex.