An electric bicycle (e-bike, eBike, etc.) is a motorized bicycle with an integrated electric motor used to assist propulsion. Many kinds of e-bikes are available worldwide, but they generally fall into two broad categories: bikes that assist the rider's pedal-power (i.e. pedelecs) and bikes that add a throttle, integrating moped-style functionality. Both retain the ability to be pedaled by the rider and are therefore not electric motorcycles. E-bikes use rechargeable batteries and typically travel up to 25 to 32 km/h (16 to 20 mph). High-powered varieties can often travel more than 45 km/h (28 mph). In some markets, such as Germany as of 2013, they are gaining in popularity and taking some market share away from conventional bicycles, while in others, such as China as of 2010, they are replacing fossil fuel-powered mopeds and small motorcycles. Depending on local laws, many e-bikes (e.g., pedelecs) are legally classified as bicycles rather than mopeds or motorcycles. This exempts them from the more stringent laws regarding the certification and operation of more powerful two-wheelers which are often classed as electric motorcycles. E-bikes can also be defined separately and treated under distinct electric bicycle laws. In UK legislation the vehicles are called EAPC or Electrically Assisted Pedal Cycle, in EU legislation EPAC or Electrically Power Assisted Cycle. E-bikes are the electric motor-powered versions of motorized bicycles, which have been in use since the late 19th century. Some bicycle-sharing systems use them. E-bikes are zero-emissions vehicles, as they emit no combustion by-products, but the environmental effects of electricity generation and power distribution and of manufacturing and recycling batteries must be accounted for. Even with these issues considered, e-bikes have a significantly lower environmental impact than cars, and are generally seen as environmentally desirable in an urban environment.
A mountain bike (MTB) or mountain bicycle is a bicycle designed for off-road cycling. Mountain bikes share some similarities with other bicycles, but incorporate features designed to enhance durability and performance in rough terrain, which makes them heavier, more complex and less efficient on smooth surfaces. These typically include a suspension fork, large knobby tires, more durable wheels, more powerful brakes, straight, extra wide handlebars to improve balance and comfort over rough terrain, and wide-ratio gearing optimised for topography and application (e.g., steep climbing or fast descending). Rear suspension is ubiquitous in heavier-duty bikes and now common even in lighter bikes. Dropper posts can be installed to allow the rider to quickly adjust the seat height (an elevated seat position is more effective for pedaling, but poses a hazard in aggressive maneuvers). Mountain bikes are generally specialized for use on mountain trails, single track, fire roads, and other unpaved surfaces. Mountain biking terrain commonly has rocks, roots, loose dirt, and steep grades. Many trails have additional technical trail features (TTF) such as log piles, log rides, rock gardens, skinnies, gap jumps, and wall-rides. Mountain bikes are built to handle these types of terrain and features. The heavy-duty construction combined with stronger rims and wider tires has also made this style of bicycle popular with urban riders and couriers who must navigate through potholes and over curbs. Typical features of a mountain bike are very wide tyres. The original 26 inch wheel diameter with ~2.125" width (ISO 559 mm rim diameter) is increasingly being displaced by 29 inch wheels with ~2.35" width (ISO 622 mm rim diameter), as well as the 27.5 inch wheel diameter with ~2.25 widths (ISO 584 mm rim diameter). Mountain bikes with 24 inch wheels are also available, sometimes for dirt jumping, or as a junior bike. Bicycle wheel sizes are not precise measurements: a 29-inch mountain bike wheel with a 622 millimetres (24.5 in) bead seat diameter (the term, bead seat diameter (BSD), is used in the ETRTO tire and rim sizing system), and the average 29" mountain bike tire is (in ISO notation) 59-622 corresponds to an outside diameter of about 29.15 inches (740 mm). It can also be made into an electric mountain bike, which can better enjoy the thrill of speed.
Electric motorcycles and scooters are plug-in electric vehicles with two or three wheels. The electricity is stored on board in a rechargeable battery, which drives one or more electric motors. Electric scooters (as distinct from motorcycles) have a step-through frame. Electric vehicles are far quieter than gasoline powered ones, so silent they may sneak up on unwary pedestrians. Some are equipped to emit artificial noise. Popular Mechanics called the comparative quiet of electric motorcycles the greatest difference between them and their gasoline counterparts, and a safety bonus because the rider can hear danger approaching. Whether a loud motorcycle is more noticeable and thus more safe than a quiet one is contested. At high speed the whine of an electric motorcycle is said to sound "like a spaceship." Electric motorcycles and scooters suffer considerable disadvantage in range, since batteries cannot store as much energy as a tank of gasoline. Anything over 130 miles (210 km) on a single charge is considered an exceptionally long range. As a result, while electric machines excel as daily commuters traveling a fixed distance round trip, on the open road riders experience inhibiting range anxiety. Also electric power trades off range against speed. For instance the current longest range electric scooter, the ZEV 10 LRC, travels 220 km (140 mi) at 89 km/h (55 mph), but according to the manufacturer the range drops to about 129 km (80 mi) at 112 km/h (70 mph). A BBC news blog reported that an Austrian bike, the Johammer J1, is capable of travelling 200 km (124 miles) on a single charge. All electric scooters and motorcycles provide for recharging by plugging into ordinary wall outlets, usually taking about eight hours to recharge (i.e., overnight). Some manufacturers have designed in, included, or offer as an accessory, the high-power CHAdeMO level 2 charger, which can charge the batteries up to 95% in an hour.
Most electric motorcycles and scooters as of May 2019 are powered by rechargeable lithium ion batteries, though some early models used nickel-metal hydride batteries. Alternative types of batteries are available. Z Electric Vehicle has pioneered use of a lead/sodium silicate battery (a variation on the classic lead acid battery invented in 1859, still prevalent in automobiles) that compares favorably with lithium batteries in size, weight, and energy capacity, at considerably less cost. EGen says its lithium-iron phosphate batteries are up to two-thirds lighter than lead acid batteries and offer the best battery performance for electric vehicles. In 2017, the first vehicle in the US to use the new Lithium Titanium Oxide (LTO) battery non-flammable battery technology is a scooter called The Expresso. This new technology charges a battery in less than 10 minutes and withstands 25,000 charges (the equivalent of 70 years of daily charges). The technology, created by Altairnano, is currently being used in China where over 10,000 urban buses run on these fast charge batteries.