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

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Leader: The unresolved Eurozone crisis

The continent that once aspired to be a rival superpower to the US is now a byword for decline, and ethnic nationalism and right-wing populism are thriving.

The eurozone crisis was never resolved. It was merely conveniently forgotten. The vote for Brexit, the terrible war in Syria and Donald Trump’s election as US president all distracted from the single currency’s woes. Yet its contradictions endure, a permanent threat to continental European stability and the future cohesion of the European Union.

The resignation of the Italian prime minister Matteo Renzi, following defeat in a constitutional referendum on 4 December, was the moment at which some believed that Europe would be overwhelmed. Among the champions of the No campaign were the anti-euro Five Star Movement (which has led in some recent opinion polls) and the separatist Lega Nord. Opponents of the EU, such as Nigel Farage, hailed the result as a rejection of the single currency.

An Italian exit, if not unthinkable, is far from inevitable, however. The No campaign comprised not only Eurosceptics but pro-Europeans such as the former prime minister Mario Monti and members of Mr Renzi’s liberal-centrist Democratic Party. Few voters treated the referendum as a judgement on the monetary union.

To achieve withdrawal from the euro, the populist Five Star Movement would need first to form a government (no easy task under Italy’s complex multiparty system), then amend the constitution to allow a public vote on Italy’s membership of the currency. Opinion polls continue to show a majority opposed to the return of the lira.

But Europe faces far more immediate dangers. Italy’s fragile banking system has been imperilled by the referendum result and the accompanying fall in investor confidence. In the absence of state aid, the Banca Monte dei Paschi di Siena, the world’s oldest bank, could soon face ruin. Italy’s national debt stands at 132 per cent of GDP, severely limiting its firepower, and its financial sector has amassed $360bn of bad loans. The risk is of a new financial crisis that spreads across the eurozone.

EU leaders’ record to date does not encourage optimism. Seven years after the Greek crisis began, the German government is continuing to advocate the failed path of austerity. On 4 December, Germany’s finance minister, Wolfgang Schäuble, declared that Greece must choose between unpopular “structural reforms” (a euphemism for austerity) or withdrawal from the euro. He insisted that debt relief “would not help” the immiserated country.

Yet the argument that austerity is unsustainable is now heard far beyond the Syriza government. The International Monetary Fund is among those that have demanded “unconditional” debt relief. Under the current bailout terms, Greece’s interest payments on its debt (roughly €330bn) will continually rise, consuming 60 per cent of its budget by 2060. The IMF has rightly proposed an extended repayment period and a fixed interest rate of 1.5 per cent. Faced with German intransigence, it is refusing to provide further funding.

Ever since the European Central Bank president, Mario Draghi, declared in 2012 that he was prepared to do “whatever it takes” to preserve the single currency, EU member states have relied on monetary policy to contain the crisis. This complacent approach could unravel. From the euro’s inception, economists have warned of the dangers of a monetary union that is unmatched by fiscal and political union. The UK, partly for these reasons, wisely rejected membership, but other states have been condemned to stagnation. As Felix Martin writes on page 15, “Italy today is worse off than it was not just in 2007, but in 1997. National output per head has stagnated for 20 years – an astonishing . . . statistic.”

Germany’s refusal to support demand (having benefited from a fixed exchange rate) undermined the principles of European solidarity and shared prosperity. German unemployment has fallen to 4.1 per cent, the lowest level since 1981, but joblessness is at 23.4 per cent in Greece, 19 per cent in Spain and 11.6 per cent in Italy. The youngest have suffered most. Youth unemployment is 46.5 per cent in Greece, 42.6 per cent in Spain and 36.4 per cent in Italy. No social model should tolerate such waste.

“If the euro fails, then Europe fails,” the German chancellor, Angela Merkel, has often asserted. Yet it does not follow that Europe will succeed if the euro survives. The continent that once aspired to be a rival superpower to the US is now a byword for decline, and ethnic nationalism and right-wing populism are thriving. In these circumstances, the surprise has been not voters’ intemperance, but their patience.

This article first appeared in the 08 December 2016 issue of the New Statesman, Brexit to Trump