Bicycles are nimble, quick, green, and affordable. They’re even better when they fold up.

Last September, Boston Mayor Michelle Wu ’07 announced plans to add 9.4 miles of new bike lanes to the existing 84 miles of marked routes in the city. She wants 50 percent of Bostonians to be within a three-minute walk from a safe, connected bike route within three years.

Let me take Mayor Wu’s bid and raise it. Not only does Boston need more cycle lanes; the future of American cities should belong to the folding pushbike. Here’s why.

I recently moved to Boston from London. My fold-up bicycle let me connect London’s cycle lanes and public transport so I could do far more with my time. I made house calls to patients, carried my bike on buses and trains, tucked it beside me in the pub, and walked it upstairs to my flat at night.

One of the biggest folding bicycle brands in Britain is Brompton. Since a pre-production run of 60 were sold in 1982, the Brompton’s small wheels and simple geometry have become a feature of London transport as distinctive as the black cab and the red bus. The reason is clear: Folding bicycles make London more livable.

My own bike is a Brompton with three gears and mudguards. In the mornings, I rode it through Victoria Park and up the towpath on the River Lea when my visits took me to Walthamstow or Chingford.

I’ve cycled through the Alps, Dolomites, and Atlas mountains, and crossed Milan during rush hour on an old touring bike, and I feel comfortable squeezing past buses on Oxford Street. The objective is that of a cat’s whiskers or a goalkeeper: to determine what will fit a given space.

My confidence comes in part from the dense mass of riders who have fanned across central London in recent years: approximately 161,000 per day. Drivers have reason to check their mirrors and pull out carefully: There’s almost always a cyclist. The more who cycle, the safer it gets.

London currently has a Congestion Charge: a £15 daily fee for driving a car in the Congestion Charge zone, which has gradually ratcheted up the cost of driving in London. The legitimacy of this measure rests on the availability of viable public transport alternatives. Fortunately, London also has at least 9,300 buses on 675 routes and 272 stations connecting 402 kilometers of London Underground track. Rail strikes notwithstanding, the way London allows its over 9.6 million residents to get around without need of a car is central to its status as a great city.

Many American cities were designed for cars, but as Robert A. Caro demonstrates in “The Power Broker,” his vast biography of dominant New York urban planner Robert Moses, no number of additional roads and bridges have sustainably allayed New York City’s infamous congestion. Millions of Americans stew needlessly for hours in their car each day.

Public transport can be an efficient, sustainable future for America. Folding bicycles can complete the link from station to front door.

Admittedly, my folding bike, priced from $1,150, cost four times more than my first car (a Ford Fiesta bought from beneath the tree of a local farmer, its chassis long since defunct, God rest it) and is only a sensible mode of transport because the city I usually work in has decent bus and rail infrastructure. Hiring a Bluebike is an affordable alternative for Bostonians, although these bikes aren’t allowed on buses, trains, or ferries.

Those who know the mirthless comedy of traffic around Harvard Square will surely agree that life in Cambridge, Boston, New York, and across the United States would be better if more Americans cycled and fewer drove while leaning furiously on their horns.

We are past the point where we can escape or ignore the effects of climate change — your Harvard credentials will not save you from our shared life and fate. To mitigate the worst effects of the changing earth, the citizens of high-income, high-emitting countries must rapidly change the way we live. It can begin with how you get to the grocery store.

I realize that asking U.S. cities to break their motorcar addiction and deliver public transport services people actually want to use may seem as quixotic as locking your arms and back into a stickman posture to force a three-gear folding bike up a mountain. But it can be done. To stand a chance of leaving this world fit to live in for generations to come, we need to change what we invest in, where we go, and how we get there.

Is that not the road to the future? Let’s get there by bicycle.

Dr. Adam Boggon is a Fulbright scholar at the Harvard T.H. Chan School of Public Health.