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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Emily Thornberry heckled by Labour MPs as tensions over Trident erupt

Shadow defence secretary's performance at PLP meeting described as "risible" and "cringeworthy". 

"There's no point trying to shout me down" shadow defence secretary Emily Thornberry declared midway through tonight's Parliamentary Labour Party meeting. Even by recent standards, the 70-minute gathering was remarkably fractious (with PLP chair John Cryer at one point threatening to halt it). Addressing MPs and peers for the first time since replacing Maria Eagle, Thornberry's performance did nothing to reassure Trident supporters. 

The Islington South MP, who voted against renewal in 2007, said that the defence review would be "wide-ranging" and did not take a position on the nuclear question (though she emphasised it was right to "question" renewal). She vowed to listen to colleagues as well as taking "expert advice" and promised to soon visit the Barrow construction site. But MPs' anger was remorseless. Former shadow defence minister Kevan Jones was one of the first to emerge from Committee Room 14. "Waffly and incoherent, cringeworthy" was his verdict. Another Labour MP told me: "Risible. Appalling. She compared Trident to patrolling the skies with spitfires ... It was embarrassing." A party source said afterwards that Thornberry's "spitfire" remark was merely an observation on changing technology. 

"She was talking originally in that whole section about drones. She'd been talking to some people about drones and it was apparent that it was absolutely possible, with improving technology, that large submarines could easily be tracked, detected and attacked by drones. She said it is a question of keeping your eye on new technology ... We don't have the spitfires of the 21st century but we do have some quite old planes, Tornadoes, but they've been updated with modern technology and modern weaponry." 

Former first sea lord and security minister Alan West complained, however, that she had failed to understand how nuclear submarines worked. "Physics, basic physics!" he cried as he left. Asked how the meeting went, Neil Kinnock, who as leader reversed Labour's unilateralist position in 1989, simply let out a belly laugh. Thornberry herself stoically insisted that it went "alright". But a shadow minister told me: "Emily just evidently hadn't put in the work required to be able to credibly address the PLP - totally humiliated. Not by the noise of the hecklers but by the silence of any defenders, no one speaking up for her." 

Labour has long awaited the Europe split currently unfolding among the Tories. But its divide on Trident is far worse. The majority of its MPs are opposed to unilateral disarmament and just seven of the shadow cabinet's 31 members share Jeremy Corbyn's position. While Labour MPs will be given a free vote when the Commons votes on Trident renewal later this year (a fait accompli), the real battle is to determine the party's manifesto stance. 

Thornberry will tomorrow address the shadow cabinet and, for the first time this year, Corbyn will attend the next PLP meeting on 22 February. Both will have to contend with a divide which appears unbridgeable. 

George Eaton is political editor of the New Statesman.