Bike-share programs have been quietly polluting for years. Now companies like Lime and Lyft are improving design and operations to deliver on sustainability promises

Jones is a unionized field bike mechanic for Bay Wheels, the regional public bicycle-sharing scheme in California’s Bay Area. It’s operated by Motivate, a subsidiary of ride–hailing giant Lyft. Guided by a specially designed Lyft app, he spends the day cruising San Francisco’s streets to fix bikes and make inspections.

Jones’ role is one way that Lyft, the largest bike-share provider in North America, is operating more efficiently and sustainably. The company has nine systems across the U.S., including Citi Bike in New York and Divvy in Chicago. It cuts emissions by repairing bikes in the field when possible, rather than transporting them to a depot, explains Caroline Samponaro, head of transit and micromobility policy at the company. “We try to complement the inherent need for the van with a variety of ways that we can minimize its impact,” she says.

Other innovations include an algorithm to optimize van routes that drivers use when swapping out e-bike batteries and rebalancing fleets. Lyft’s Bike Angels incentive program also encourages bike-share users to return bikes to the docking stations where they will be most useful, another way to cut down on van use.

Shared micromobility—in which bikes and scooters, often electric, are rented on city streets—is a small segment of the urban transportation market, but one that is starting to grow beyond novel recreational use. As this happens, its touted environmental benefits are facing tougher scrutiny. Lyft’s operational improvements are part of an industrywide response to address sustainability.

Not so green?

The shared micromobility industry is young. Bird only launched the first e-scooter sharing service in Santa Monica in 2018. Tens of companies jostle for city contracts and permissions to operate, and many have both e-bikes and e-scooters in their stable. Data from market research firm Mobility Foresights show that Lime and Bird have the largest share of the e-scooter market in the U.S. Tier is the biggest European operator, and it recently moved into the U.S. with the acquisition of e-scooter label Spin. 

The industry took a hit during the pandemic but is rebounding. The latest report from the North American Bikeshare and Scootershare Association shows shared micromobility trips started to surpass 2019 levels in mid-2021 and remain on an upward trajectory. In 2021, an estimated 128 million trips were taken in the U.S., Canada, and Mexico across 232,000 shared bikes and scooters operating in nearly 300 cities.

Yet profitability for many of the companies remains a struggle: The fight isn’t only for market share, but for survival. Greater industry consolidation seems likely.

While replacing an individual car trip with any micromobility ride is certainly better for the environment, early published research on the overall carbon emissions impact of shared e-bikes and e-scooters has mostly found they are net contributors to greenhouse gas emissions. 

“The research shows that [these companies] are perhaps not as green as they appear to be,” says Kelly Clifton, a professor at the University of British Columbia who studies travel behavior and has reviewed the field.  

The studies typically balance two elements. The first is an estimate of the vehicle’s total carbon footprint from “cradle to grave,” including emissions from its manufacture, what it takes to operate and maintain, and the plan for its recycling—all of which is boiled down to a single number through a life-cycle assessment (LCA).

The second looks at the emissions that shared micromobility saves based on the type of trip it replaces, known as mode shift. That information is gathered through user surveys that determine what individuals might otherwise have taken to get where they needed to go. The evidence, notes Clifton, points to shared micromobility replacing walking or public transit options more often than car trips.

One recent study of micromobility in Zurich found that shared e-bikes and e-scooters caused a net increase in CO2 emissions based on a car replacement rate of 15%, whereas owned e-bikes and e-scooters led to a net decrease in emissions because owners tended to use them more often in lieu of cars. Another study centered on Barcelona reached a similar conclusion about that city’s shared e-bikes and e-mopeds. There, the average car replacement rate was found to be as low as 4%. 

“It is counter to the argument that micromobility is going to solve climate change,” says study author Oriol Marquet, a transport researcher at the Autonomous University of Barcelona. 

‘A rapidly evolving industry’

Critics say this research fails to capture the current state of what is a rapidly evolving industry moving in the right direction. The data used in the studies relies on older generations of products and operational practices, in part because the companies have been reluctant to share updated figures. It doesn’t capture design improvements that have extended the life span of fleets, for example. 

“They are actually built and engineered now to last,” says Melinda Hanson, founder and principal at mobility consulting firm, Brightside. She previously led the sustainability team at Bird. 

The industry has also embraced higher capacity batteries that can be swapped out on-site. Some providers are charging their batteries with renewable energy or purchasing carbon offsets. Many companies are also transitioning to electric vans. 

Ailin Huang, head of sustainability at Tier, notes that the LCA value for its e-scooter has fallen by over 60% since the first model it put out three years ago, and the latest model is projected to last on average five years or more. Fleet-wide swappable batteries, implemented last year, have helped reduce the company’s operational footprint by over 80%, she adds.

More green innovations are on the way, such as greater use of recycled aluminum in vehicle frames to reduce life-cycle emissions. 

There are also efforts to improve transparency by making LCA data publicly available. Lyft published LCAs for its bike and scooter range last week, claiming to be the first shared micromobility company to have publicly released those documents in full. Bird and Lime recently published LCA summaries for the first time.

LCA values mostly fall within a narrow range of one another and can be difficult to compare, another issue that is being addressed. The industry is working with cities and experts to develop guidance on how carbon accounting standards should be applied, so everyone is on the same page. That should enable cities to confidently identify which subset of operators are doing better on emissions, says Leah Lazer, a research associate at the New Urban Mobility Alliance (NUMO), which connects different stakeholders around urban transport issues and is overseeing the effort.

Meanwhile, companies and advocates note that mode-shift rates vary by city. Micromobility has greater potential to shift people out of cars in the U.S. than in Europe, because Americans use cars more and have fewer alternatives. Rates are also likely to change over time, as people grow accustomed to using micromobility options and integrate them into their daily routines. 

“In some places like Portland, the longer the shared micromobility systems are in place, the more they are substituting car trips,” says John MacArthur, who studies micromobility at Portland State University. Mode-shift data, he adds, doesn’t reveal everything: While shared micromobility might replace a walking trip, it can also make public transit more accessible. 

Both Lyft and Uber-backed Lime note that introducing the option to use micromobility in their ride-sharing apps has encouraged users to mode-shift away from cars. 

“By the numbers, we’re seeing that work,” says Lyft’s Samponaro. In the U.S., Lyft says it averages a 36% car replacement rate for its bike-share program, while Lime gives a figure of 27% for its e-scooters. Tier estimates 25% across both products.

Broader shifts in mobility

The industry points out that the responsibility for shifting car habits doesn’t lie solely with them. To attract more people out of cars requires rethinking city infrastructure, such as adding more bike lanes and expanding barriers between cars, so riders can feel safer. 

“Cities could be doing a lot more,” says Harriet Tregoning, director of NUMO. And, she adds, she would like to see cars, including electric vehicles, held to the same environmental standards as micromobility services. “We’re not doing a life-cycle analysis for those vehicles,” she notes.

This October, researchers at the Fraunhofer Institute for Systems and Innovation Research in Germany published a report on behalf of Lime that shows that the company’s latest generation of shared e-scooters and e-bikes can reduce net carbon emissions. The study looked at six global cities: Berlin, Düsseldorf, Melbourne, Paris, Seattle, and Stockholm. It found net reductions in every city except Berlin, where e-bikes produced a slight net increase in emissions because of a lower car replacement rate. Lyft is expected to publish an analysis with a similar conclusion next year.

Overall, it’s a promising sign that the industry’s efforts are paying off.

“If done well, e-micromobility will reduce carbon in cities around the world and can be a fundamental of a city’s decarbonization strategy,” says Andrew Savage, Lime’s head of sustainability.