E-bikes are zero-emissions vehicles, as they emit no combustion by-products. However, the environmental effects of electricity generation and power distribution and of manufacturing and disposing of (limited life) high storage density batteries must be taken into account. Even with these issues considered, e-bikes are claimed to have a significantly lower environmental impact than conventional automobiles, and are generally seen as environmentally desirable in an urban environment.[65]
Electric bikes advertise with a huge array of varying ranges, but what is the dominant factor is range? Electric bike range is determined by the battery, and just like other lithium battery products like laptops and cell phones the batteries performance can fluxuate based on a variety of external factors.  Extreme cold, rider weight, head winds, hills, rough terrain, tire pressure and many other factors.   But since we need to start somewhere to get the general range that a battery can produce there is baseline that we can reference to get a good indicator of range. Take a look at...
Further innovations increased comfort and ushered in a second bicycle craze, the 1890s Golden Age of Bicycles. In 1888, Scotsman John Boyd Dunlop introduced the first practical pneumatic tire, which soon became universal. Willie Hume demonstrated the supremacy of Dunlop's tyres in 1889, winning the tyre's first-ever races in Ireland and then England.[28][29] Soon after, the rear freewheel was developed, enabling the rider to coast. This refinement led to the 1890s invention[30] of coaster brakes. Dérailleur gears and hand-operated Bowden cable-pull brakes were also developed during these years, but were only slowly adopted by casual riders.
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.
Electric-assisted bicycles, also referred to as "e-bikes," are a subset of bicycles that are equipped with a small attached motor. To be classified as an "electric-assisted bicycle" in Minnesota, the bicycle must have a saddle and operable pedals, two or three wheels, and an electric motor of up to 1,000 watts, as well as meet certain federal motor vehicle safety standards. The motor must disengage during braking and have a maximum speed of 20 miles per hour (whether assisted by human power or not). Minn. Stat. §169.011, subd. 27.
On the other hand, the battery doesn’t lock into the bike, which means you can’t just leave it on your bike when you park at the bike rack. Anyone could walk by and simply remove your battery. That seems like an oversight to me, though perhaps the designers assumed that such a small battery would just be easy to take with you. And it is. My wife could probably lose this battery in her purse.