Scooting off the wall: a transportation fad

In the United States, small “electric scooters” became a personal transportation fad in 2018, after starting the previous year on the West Coast. While some units are being sold to individuals, the great majority are bought by “ride share” companies who rent them out. Based on data from Portland, OR, which has years of experience tracking personal transportation, the average electric-scooter rental is for a ride of a little over a mile and a few minutes. Electric-scooter ride-share companies include Bird, Spin, Lime, Lyft, Uber, Skip, Tier, Dott, Scoot, Jump, Wind, Bolt, Grin, Ride and Yellow.

Features: Models of electric scooters often found from “ride-share” companies–such as Xiaomi model MS365 and Segway model ES1–have motors rated at about 1/3 horsepower. Weight is about 25 lb, battery life is around an hour for 10 miles of typical travel, and full recharging time is around 4 hours. Usual speeds on level roads vary from about 3 to 12 miles per hour.

Prices for popular electric scooters sold to individuals range around $500, with others selling for about $200 to $800. At online forums, many purchasers rate reliability of popular electric scooters as poor, with up to a quarter finding major defects, severe wear or outright failure after less than a month of use. Reported problems include misaligned parts, stuck controls, loose frames and handlebars, rattling motors and brakes, battery fires, worn tires and poor customer service.

Stability: A typical electric scooter has two small, solid rubber tires–about 8-inch diameter on 33-inch axle spacing. The operator stands on a narrow shelf at axle height, about 4 inches off the road surface, with the center of gravity for a six-foot-tall standing operator about 40 inches above the axles and 1/3 the axle spacing behind the front axle.

By comparison, a bicycle provides a more stable ride with a rider normally seated. A lightweight has 26-inch diameter, air-filled tires on 40-inch axle spacing, with the center of gravity for a six-foot-tall seated rider about 30 inches above the axles and 2/3 the axle spacing behind the front axle. Both gyroscopic forces and stabilizing forces during turns are substantially greater for bicycles than for electric scooters, while the torsion moment from the center-of-gravity to the axle height is less.

Hazards: A bicycle will ride over many obstacles, while a typical curb will stop an electric scooter stone cold–pitching the operator over the handle bars, likely to strike the ground face first. Reports are starting to accumulate. A majority of injuries with electric scooters come from collisions with obstacles, not with other vehicles or pedestrians. Face lacerations, concussions, and broken noses, jaws and arms are common in electric scooter crash reports.

As in several other places, Massachusetts laws require operators of electric scooters to wear helmets. While some places forbid electric scooters operating on sidewalks, Massachusetts laws do not. The state also requires electric scooters to have working stop and directional signals and does not allow operation after sunset and before sunrise. Surveys show poor compliance with such laws. Portland, OR, found only 10 percent of operators wearing helmets. Los Angeles found fewer than 5 percent. Electric scooters currently being rented in Brookline, MA, lack stop and directional signals required by state laws.

Injury rates from operating electric scooters are alarming. Portland, OR, the U.S. community with the longest and most extensive measurements, found a rate of 220 injuries per million passenger-miles. By comparison, the injury rate for public transit in the U.S. is around 0.2 injuries per million passenger-miles. For the same distance of travel, operating an electric scooter is around 1,000 times as dangerous as using public transit.

Environmental factors: When on duty, electric scooters are energy-efficient, using about 20 Watt-hours per mile. For comparison, a Tesla model S electric automobile uses about 330 Watt-hours per mile. During the after-duty hours, however, rental scooters are collected by contractors, taken to garages for charging, then trucked back to public locations. For each mile when on duty, a typical rental scooter spends another mile in a 4,000-pound, gasoline-powered pick-up truck. The efficiency when on duty is wiped out. It is more efficient and kinder to the environment to drive an ordinary car.

– Craig Bolon, Brookline, MA, April 8, 2019


Yasmin Khorram, CDC is studying the rise in e-scooter injuries, CNBC, March 8, 2019

Jonathan Maus, Scooter company reps scolded by Oregon legislators over helmet law proposal, Bike Portland (OR), February 20, 2019

Chuck Temple, Electric scooter safety report: Austin and Portland, Medium (San Francisco, CA), February 8, 2019

Ryan Felton, E-scooter ride-share industry leaves injuries and angered cities in its path, Consumer Reports, February 5, 2019

Sarah Holder, Electric scooters sent nearly 250 riders to Los Angeles emergency rooms last year, City Lab (New York, NY), January 29, 2019

Megan Rose Dickey, Electric scooter wars, Tech Crunch, December 23, 2018

Will Yakowicz, Bird scooter charging is one level up from collecting cans, Inc Magazine, December, 2018

Adam Podgorski et al., AG2800 life cycle assessment, Ninebot by Segway KickScooter ES2, KTH Royal Institute of Technology (Stockholm, Sweden), December, 2018 (in English)

Ninebot ES1 electric scooter description and forum, Amazon, 2018

Ninebot ES1 electric scooter specifications, Segway, 2018

Rail transit safety data, U.S. Federal Transit Administration, December, 2016

David Noland, Life with Tesla model S, Green Car Reports (Denver, CO), March 10, 2014

A.L. Schwab and J.P. Meijaard, A review on bicycle dynamics and rider control, Vehicle System Dynamics 51(7):1059-1090, 2013

Motorized scooter operation regulations, Massachusetts General Laws C. 90, S. 1E

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