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 Images
Show Hide image

Autumn Statement 2015: George Osborne abandons his target

How will George Osborne close the deficit after his U-Turns? Answer: he won't, of course. 

“Good governments U-Turn, and U-Turn frequently.” That’s Andrew Adonis’ maxim, and George Osborne borrowed heavily from him today, delivering two big U-Turns, on tax credits and on police funding. There will be no cuts to tax credits or to the police.

The Office for Budget Responsibility estimates that, in total, the government gave away £6.2 billion next year, more than half of which is the reverse to tax credits.

Osborne claims that he will still deliver his planned £12bn reduction in welfare. But, as I’ve written before, without cutting tax credits, it’s difficult to see how you can get £12bn out of the welfare bill. Here’s the OBR’s chart of welfare spending:

The government has already promised to protect child benefit and pension spending – in fact, it actually increased pensioner spending today. So all that’s left is tax credits. If the government is not going to cut them, where’s the £12bn come from?

A bit of clever accounting today got Osborne out of his hole. The Universal Credit, once it comes in in full, will replace tax credits anyway, allowing him to describe his U-Turn as a delay, not a full retreat. But the reality – as the Treasury has admitted privately for some time – is that the Universal Credit will never be wholly implemented. The pilot schemes – one of which, in Hammersmith, I have visited myself – are little more than Potemkin set-ups. Iain Duncan Smith’s Universal Credit will never be rolled out in full. The savings from switching from tax credits to Universal Credit will never materialise.

The £12bn is smaller, too, than it was this time last week. Instead of cutting £12bn from the welfare budget by 2017-8, the government will instead cut £12bn by the end of the parliament – a much smaller task.

That’s not to say that the cuts to departmental spending and welfare will be painless – far from it. Employment Support Allowance – what used to be called incapacity benefit and severe disablement benefit – will be cut down to the level of Jobseekers’ Allowance, while the government will erect further hurdles to claimants. Cuts to departmental spending will mean a further reduction in the numbers of public sector workers.  But it will be some way short of the reductions in welfare spending required to hit Osborne’s deficit reduction timetable.

So, where’s the money coming from? The answer is nowhere. What we'll instead get is five more years of the same: increasing household debt, austerity largely concentrated on the poorest, and yet more borrowing. As the last five years proved, the Conservatives don’t need to close the deficit to be re-elected. In fact, it may be that having the need to “finish the job” as a stick to beat Labour with actually helped the Tories in May. They have neither an economic imperative nor a political one to close the deficit. 

Stephen Bush is editor of the Staggers, the New Statesman’s political blog.