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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How will Theresa May meet her commitment to low-earners?

The Prime Minister will soon need to translate generalities into specifics. 

The curtailed Conservative leadership contest (which would not have finished yet) meant that Theresa May had little chance to define her agenda. But of the statements she has made since becoming prime minister, the most notable remains her commitment to lead a government "driven not by the interests of the privileged few, but by yours." 

When parliament returns on 5 September, and the autumn political season begins, May will need to translate this generality into specifics. The defining opportunity to do so will be the Autumn Statement. Originally intended by George Osborne to be a banal update of economic forecasts, this set-piece more often resembled a second Budget. Following the momentous Brexit vote, it certainly will under Philip Hammond. 

The first priority will be to demonstrate how the government will counter the threat of recession. Osborne's target of a budget surplus by 2020 has wisely been abandoned, granting the new Chancellor the freedom to invest more in infrastructure (though insiders make it clear not to expect a Keynesian splurge).

As well as stimulating growth, Hammond will need to reflect May's commitment to those "just managing" rather than the "privileged few". In her speech upon becoming prime minister, she vowed that "when it comes to taxes, we’ll prioritise not the wealthy, but you". A natural means of doing so would be to reduce VAT, which was increased to a record high of 20 per cent in 2010 and hits low-earners hardest. Others will look for the freeze on benefit increases to be lifted (with inflation forecast to rise to 3 per cent next year). May's team are keenly aware of the regressive effect of loose monetary policy (low interest rates and quantitative easing), which benefits wealthy asset-owners, and vow that those who lose out will be "compensated" elsewhere. 

A notable intervention has come from Andrew Tyrie, the Conservative chair of the Treasury select committee. He has called for the government to revive the publication of distributional analyses following Budgets and Autumn Statements, which was ended by George Osborne last year (having been introduced by the coalition in 2010). 

In a letter to Hammond, Tyrie wrote: "I would be grateful for an assurance that you will reinstate the distributional analysis of the effects of the budget and autumn statement measures on household incomes, recently and mistakenly discontinued by your predecessor." He added: "The new prime minister is committing her government to making Britain a country that works 'not for a privileged few, but for every one of us'. A high level of transparency about the effects of tax and welfare policy on households across the income distribution would seem to be a logical, perhaps essential starting point." 

Whether the government meets this demand will be an early test of how explicit it intends to be in reducing disparities. 

George Eaton is political editor of the New Statesman.