Almost half of the electric scooter companies in Paris have suspended or scaled back operations in the past week, after the French capital's mayor vowed to crack down on the "anarchy" caused by the sudden proliferation of thousands of new two-wheeled vehicles on its streets.
At the same time, many of the same start-ups are rushing to launch in cities across Germany, after Europe's largest economy legalised the vehicles last month.
"Germany is in scooter mania," said Boris Mittermüller, co-founder and chief operating officer at Circ, one of the first companies to launch there. "The weather is perfect. We really have a lot of momentum. Even we are surprised."
European scooter start-ups including Circ, Voi and Tier are racing against US rivals Lime and Bird to establish themselves in Germany. Specific vehicle requirements such as dual brakes and licence plate holders are forcing the start-ups to design and manufacture new models especially for the German market.
"It's the next war — the next Paris right now is Germany," said Maxim Romain, Dott's co-founder and chief executive. "Everyone is focusing on it."
That is fuelling a fresh fundraising drive in what is already a crowded European mobility market. After Amsterdam-based Dott announced a €30m round on Friday, executives at Circ (formerly known as Flash) and Voi say they are also in discussions with investors about raising new capital.
"2019 is a super important year for micro-mobility companies in Europe, especially now with Germany opening up," said Mr Mittermüller. "Obviously we will have to raise more capital."
The record of start-ups in Paris, which quickly became one of the world's biggest scooter markets, will be vital to convincing investors to reopen their cheque books. More than $1.5bn has already been poured into scooter ventures around the world, little more than two years after the new transportation concept was introduced.
A year after Silicon Valley-based Lime became the first scooter company to launch in Paris, the city and its residents have become unwitting guinea pigs for a dozen different scooter ventures. Some estimates suggest that more than 20,000 scooters have been available across Paris over recent months. After a winter slowdown, growth has returned with the arrival of spring.
"It was the most competitive market, until recently — everyone was there," said Mr Romain. "It's a very tough market. It's a really big city, so operationally it's hard to manage. You definitely have a lot of vandalism or theft."
While it initially proved a bonanza for the scooter operators, city officials have been forced to abandon their original laissez-faire attitude after complaints from some residents.
"It's not far from anarchy and it's extremely difficult for a city like ours to manage this service," Anne Hidalgo, Paris mayor, said last month.
Scooter operators argue that their vehicles can help ease congestion and pollution in cities as many look to limit cars in downtown areas. But they concede that Paris has been an extreme experiment in the future of transportation.
"It's so fascinating to see how fast a city can change but you also see a lot of pain points," said Fredrik Hjelm, chief executive at Voi. "There are several unprofessional companies trying their luck. We understand that people are pissed off."
He said Voi had "paused" its operations in Paris while it upgraded its fleet, with plans to return to full capacity "in a few weeks".
Tier said it had also pulled its scooters off the streets of Paris before it returns in two or three weeks with a new scooter model. Smaller operators Bolt, Wind and Ufo have largely disappeared from Paris over the past week, while Usain Bolt-backed B Mobility only has 65 scooters available.
"You need a significant fleet size to be someone in Paris," said Mr Mittermüller. "That comes at a capital and operational cost, so smaller players probably don't have a chance in Paris."
Wayne Ting, Lime's global head of operations and strategy, predicted that 2019 will be "a clarifying year" for scooter companies.
Capital costs are rising as new markets such as Germany open up, but investors are also becoming more cautious. Few scooter rental operators have proved that strong early adoption from consumers can be turned into a long-term sustainable business.
"You're starting to see a lot of risk associated to the competitive landscape," said Mr Romain. "So a number of [investors] want to wait a bit and see if [start-ups] can build something that grows profitably and if one is going to be the clear winner."
One investor in the industry was more blunt on the challenges ahead for the crowded European scooter market: "We'll probably see more companies going out of business towards the end of this year."