A motorized scooter is a powered stand-up scooter using a small utility gas engine or electric motor. These scooters are generally designed with a large deck in the center on which the rider stands. The first production scooter, the "Sport" was released by Go-Ped in 1985. Recently electric kick scooters have grown in popularity with the introduction of ride share companies that use apps that allow users to rent the scooters by the minute. These have been introduced in large cities such as Washington D.C., Las Vegas, San Francisco, Austin, and Denver. Other large cities like Seattle are trying to keep these scooter sharing companies out until they can modify laws and roads to make them safer. Fans of the scooters see them as cheap and easy alternatives to zip around the city, while others have their doubts about the long term impact. Certainly, these scooters could be a great solution in cities where traffic is so congested it has come to a standstill, but concerns about safety and feasibility should not be ignored. Companies should ensure that riders are aware of local laws and give safety warnings, maintain scooters including fixing or removing broken ones from public areas, and do their due diligence to make sure that riders and scooters do not become a nuisance. Riders can stay safe by checking their local laws, taking precautions such as wearing helmets, and being aware of their surroundings while riding.
- 1915: Autoped introduces its stand-up scooter. Pulling back on the handlebar disengaged the clutch and applied the brake. Autoped continued production until 1921; Krupp of Germany built the Autoped under license from 1919 to 1922.
- 1986: Go-Ped introduces the first production stand-up scooters the "Roadster" and the "Sport"
- May 2001: Go-Ped introduces the first full suspension stand-up electric scooter, the "Hoverboard."
- 2004: Evo Powerboards introduces the first scooter with a two-speed transmission, the "2x."
- November 2009: Go-ped introduces their first completely propane powered scooter and go-kart, the "GSR Pro-Ped" and the "GSR Pro-Quad"
- 2013-2014: light electric folding scooters based on lithium batteries and brushless hub motors become available.
- 2018: dockless scooter-sharing systems roll out in major cities, largely as expansions of bike-sharing systems.
Electric kick scooters have generally surpassed gas engined scooters in popularity since 2000. They usually have two hard small wheels, with a foldable chassis, usually aluminum. Some kick scooters have 3 or 4 wheels, or are made of plastic, or are large, or do not fold. High performance trickster scooters made for adults resemble the 19th century penny-farthing, with a much larger wheel in front. Electric kick scooters differ from mobility scooter in that they also allow human propulsion, and have no gears. Range typically varies from 5 to 50 km (3 to 31 mi), and maximum speed is around 30 km/h (19 mph).
In 2017, some bicycle-sharing companies such as Lime, and some scooter-only companies, like Bird, began offering dockless electric kick scooter sharing services. This segment of the micro-mobility market made large inroads in 2018, with numerous dockless electric scooters appearing in major cities worldwide, sometimes in controversial and contentious unsanctioned roll-outs, such as in San Francisco.
Motorized kick scooters are used in law enforcement, security patrolling  and leisure. New ride sharing systems have made electric scooters easily accessible. They are popular in urban areas, and are used as an alternative to bicycling or walking. Ride sharing companies first started dropping these scooters off in large US cities in 2018, and the need for short distance easy access transportation in many cities has meant that they have become increasingly popular with more and more companies looking to join the market.
Health and Safety
Electric scooters can pose as an environmentally friendly alternative personal mode of transportation that has appeal in urban settings and for short distances but are not exempt from the vulnerabilities users may encounter in road traffic injuries similar to exposures pedestrians and bicyclists have sharing the roads. For example, Israel has seen over 120,000 import of e-bike and e-scooters over a two year time period, but due to poor cycling infrastructure, cyclist are often forced on pedestrian sidewalks and pedestrians use bike lanes and thus increase the risk of traffic collision. As availability and demand for electric scooters increases alongside often powerful motors with capacities to reach up to 50 miles per hour, the number of traffic accident cases have also increased. Israel witnessed a six-fold increase of e-bike and e-scooter accidents over a span of three years and China found a four-fold increase in injury rate and a six-fold increase in mortality rates. However, significant gaps remain in the knowledge about the safety measures and impact of electric scooters. As electric scooters become more popular in urban and high traffic settings, user safety poses as a major concern alongside with other health risks for drivers, pedestrians, cyclists and other vulnerable groups such as elderly and children sharing the road. A study conducted in China assessed risky behaviors of e-bike, e-scooter, and bicycle riders at crossing signalized intersections and found three different types of risky behaviors including stopping beyond the stop line, riding in motor lanes, and riding against traffic. The same study found that those riding e-scooters are more likely to engage in risky behaviors. In specific, e-scooter riders were more likely to ride in motor lanes and ride against the flow of traffic though there is high variability in the types of accidents that occur and can vary based on time of day. Understanding the health impacts of electric scooters should be considered when developing standards and policies for these new but prevalent modes of transportation. For example, policymakers should highly consider whether electric bicycles and electric scooters belong in bicycle lanes, car lanes, or on the roadways at all. Underreporting poses as additional gaps in knowledge, as minor crashes, for example, tend to be underreported and thus unaccounted for in overall electric scooter injury prevalence and there exist gaps in research on injuries related to electric scooters. Scooter-sharing systems such as Lime or Bird include safety precautions on the scooters themselves such as, “helmet required, license required, no riding on sidewalks, no double riding, 18+ years old.” Apps used to unlock and rent the scooters will also have safety reminders and ask the riders to abide by local laws while using them. However, these recommendations are not always followed, and the difference in laws between cities and states makes regulation difficult.
Legality (United States)
In many areas in the United States, motorized scooters are not street legal, as they cannot be tagged, titled, insured, and do not meet federal requirements for lights or mirrors. Particular localities may have further ordinances that limit the use of motorized scooters. The top speed of the average motorized scooters is around 20 miles per hour (32 kilometers per hour). Due to their small wheels, motorized scooters are not typically safe for street use as even the smallest bumps can cause an accident.
California requires a person riding a motorized scooter on a street must be 16 years of age or older, have a valid driver's license, be wearing a bicycle helmet, have no passengers, and otherwise follow the same rules of the road the same as cars do. The motorized scooter must have brakes, may not have handlebars raised above the operator's shoulders, and if ridden at night must have a headlight, a taillight, and side reflectors. A motorized scooter may not be operated on sidewalks or on streets if the posted speed limit is over 25 mph (40 km/h) unless in a Class II bicycle lane.
In Washington, D.C., motorized scooters are classified as Personal Mobility Devices, and are therefore not considered motor vehicles. This means there is no inspection, license, insurance, or registration required. Additionally, this means that motorized scooters are allowed on the sidewalks, and helmets are not required. 
In Atlanta, motorized scooters are considered Electric Personal Assistive Mobility Devices, meaning they can be used on sidewalks and highways where the speed limit is at most 35 miles per hour, or in the bike lane. The law also specifies that users of Electric Personal Assistive Mobility Devices, including motorized scooter riders, "have the same rights and duties as prescribed for pedestrians".
Scooter sharing companies have rules for operation printed on both the scooter and in the app, which includes instructions to not ride on the sidewalk. Since the laws regarding motorizes scooters vary from state to state, the scooter sharing instructions can differ from the local law.
Wheels and tires
There are two general categories of tires on which stand-up scooters travel—hard tires and air tires. Hard tires are generally 6 inches (150 mm) in diameter and constructed of a hard-plastic insert surrounded by a solid rubber tire. Air tires are most often 10 inches (250 mm) in diameter. They are constructed of a steel or aluminum split rim, an inner tube and rubber tire. Other, less common wheel and tire types include 8 inches (200 mm) and 13 inches (330 mm) air tires.
The most simplistic drive mechanism of stand-up scooters is the "spindle" drive. This drive mechanism puts an extension of the engine's output shaft, the spindle, in direct contact with the rear tire of the scooter. In order to function correctly, the tire must have a clean, dry surface which the spindle will be able to effectively interact with. Scooters with this type of direct transmission can be pull started with the rear wheel off of the ground or "bump" started by forcefully pushing the scooter with the rear tire in contact with the ground.
Belt reduction drives use the combination of wide flat "cog" belts and pulleys to transfer power to the rear wheel. Like chain drives, belt drives include a centrifugal clutch. Belt drives are more susceptible to breakage in off-road conditions.
The suspension systems of stand-up scooters range from simplistic spring based fork systems to the complicated, dampened cam-link and C.I.D.L.I suspension mechanisms or a hybrid combination of wooden deck, coil spring, and dampers (e.g. ZUKBOARD CITY).
Brake systems of kick scooters can range from Disc Brake system, magnetic brake (used for energy consumption), or the less efficient Hydraulic Brakes, where brakes can be placed on either -or both- the front and back wheel(s).
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