We still don’t really know how bicycles work

Forget mysterious dark matter and the inexplicable accelerating expansion of the universe; the bicycle represents a far more embarrassing hole in the accomplishments of physics.

Let’s be honest, a bit of the pleasure at Chris Froome’s victory in the Tour de France is down to this being our second victory in a row and to the thought that the French haven’t won it since 1985. What must be worse for them, though, is that when it comes to the science of team cycling, even the Belgians are in front.
 
At the University of Mons, researchers are developing something called the Anaconda. It’s never going to be much of a speed machine because it is, in effect, a chain of monocycles with handlebars. These units are connected, by means of hinges that allow them to snake along, to a normal two-wheeled bike at the front. Every rider in the chain can be going in a slightly different direction, which means it takes an enormous amount of control and collaboration to move the thing forward. According to Olivier Verlinden, chief engineer on the project, the main qualification for riders is to be unafraid of falling off.
 
It’s fun, apparently. The idea is to unleash it as a beach-resort bike, the kind of thing that stag and hen parties will use to terrorise seaside towns across the world. But it is also scientifically interesting. Why? Because we still don’t really know how bicycles work.
 
It is rare that most people appreciate the bicycle, but it is quite an extraordinary machine. Push a riderless bike, letting it roll freely at high enough speeds, and it can withstand pushes from the side – it will wobble a little, but quickly recover. In the conventional analysis, that is because the gyroscopic force of the front wheel, its mass and the spontaneous turn of the handlebars all act together to keep the bicycle rolling forwards. This has something to do with the gyroscopic effect, the force that keeps a spinning top upright. You can feel this by removing a wheel from your pushbike and spinning it while you hold the axle spindles. If you try to change the orientation of the wheel, you’ll feel it push back against you.
 
The first mathematical analysis of bicycles suggested that this is also what keeps a moving bike on its wheels. But although the equations were written down in 1910, physicists always had nagging doubts about whether this was the whole story.
 
The most definitive analysis came exactly a century later. It involved an experimental bicycle that had all its gyroscopic effects cancelled out by a system of counter-rotating wheels. The effort of building such a strange contraption was worth it: the resulting paper was published the prestigious journal Science.
 
The publication plunged bicycle dynamics back into chaos. It turns out that taking into account the angles of the headset and the forks, the distribution of weight and the handlebar turn, the gyroscopic effects are not enough to keep a bike upright after all. What does? We simply don’t know. Forget mysterious dark matter and the inexplicable accelerating expansion of the universe; the bicycle represents a far more embarrassing hole in the accomplishments of physics.
 
And it may not be solved any time soon; very few researchers are working full-time on bicycle dynamics and there’s very little money in it. Once we’ve discovered exactly how these contraptions work, it might be possible to come up with bold new designs of bicycle – perhaps even better than the Anaconda. But nobody is desperate for that to happen; not even the French.
 
Maybe that’s OK. In an age where we have worked out the history of the cosmos and the secret of life, it’s rather nice that the humble bicycle keeps our feet on the ground. 
 
Cyclists during the Tour de France. Photo: Getty

Michael Brooks holds a PhD in quantum physics. He writes a weekly science column for the New Statesman, and his most recent book is At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise.

This article first appeared in the 29 July 2013 issue of the New Statesman, Summer Double Issue

Photo: Getty
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The rise of the green mayor – Sadiq Khan and the politics of clean energy

At an event at Tate Modern, Sadiq Khan pledged to clean up London's act.

On Thursday night, deep in the bowls of Tate Modern’s turbine hall, London Mayor Sadiq Khan renewed his promise to make the capital a world leader in clean energy and air. Yet his focus was as much on people as power plants – in particular, the need for local authorities to lead where central governments will not.

Khan was there to introduce the screening of a new documentary, From the Ashes, about the demise of the American coal industry. As he noted, Britain continues to battle against the legacy of fossil fuels: “In London today we burn very little coal but we are facing new air pollution challenges brought about for different reasons." 

At a time when the world's leaders are struggling to keep international agreements on climate change afloat, what can mayors do? Khan has pledged to buy only hybrid and zero-emissions buses from next year, and is working towards London becoming a zero carbon city.

Khan has, of course, also gained heroic status for being a bête noire of climate-change-denier-in-chief Donald Trump. On the US president's withdrawal from the Paris Agreement, Khan quipped: “If only he had withdrawn from Twitter.” He had more favourable things to say about the former mayor of New York and climate change activist Michael Bloomberg, who Khan said hailed from “the second greatest city in the world.”

Yet behind his humour was a serious point. Local authorities are having to pick up where both countries' central governments are leaving a void – in improving our air and supporting renewable technology and jobs. Most concerning of all, perhaps, is the way that interest groups representing business are slashing away at the regulations which protect public health, and claiming it as a virtue.

In the UK, documents leaked to Greenpeace’s energy desk show that a government-backed initiative considered proposals for reducing EU rules on fire-safety on the very day of the Grenfell Tower fire. The director of this Red Tape Initiative, Nick Tyrone, told the Guardian that these proposals were rejected. Yet government attempts to water down other EU regulations, such as the energy efficiency directive, still stand.

In America, this blame-game is even more highly charged. Republicans have sworn to replace what they describe as Obama’s “war on coal” with a war on regulation. “I am taking historic steps to lift the restrictions on American energy, to reverse government intrusion, and to cancel job-killing regulations,” Trump announced in March. While he has vowed “to promote clean air and clear water,” he has almost simultaneously signed an order to unravel the Clean Water Rule.

This rhetoric is hurting the very people it claims to protect: miners. From the Ashes shows the many ways that the industry harms wider public health, from water contamination, to air pollution. It also makes a strong case that the American coal industry is in terminal decline, regardless of possibile interventions from government or carbon capture.

Charities like Bloomberg can only do so much to pick up the pieces. The foundation, which helped fund the film, now not only helps support job training programs in coal communities after the Trump administration pulled their funding, but in recent weeks it also promised $15m to UN efforts to tackle climate change – again to help cover Trump's withdrawal from Paris Agreement. “I'm a bit worried about how many cards we're going to have to keep adding to the end of the film”, joked Antha Williams, a Bloomberg representative at the screening, with gallows humour.

Hope also lies with local governments and mayors. The publication of the mayor’s own environment strategy is coming “soon”. Speaking in panel discussion after the film, his deputy mayor for environment and energy, Shirley Rodrigues, described the move to a cleaner future as "an inevitable transition".

Confronting the troubled legacies of our fossil fuel past will not be easy. "We have our own experiences here of our coal mining communities being devastated by the closure of their mines," said Khan. But clean air begins with clean politics; maintaining old ways at the price of health is not one any government must pay. 

'From The Ashes' will premiere on National Geograhpic in the United Kingdom at 9pm on Tuesday, June 27th.

India Bourke is an environment writer and editorial assistant at the New Statesman.

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