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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It's Gary Lineker 1, the Sun 0

The football hero has found himself at the heart of a Twitter storm over the refugee children debate.

The Mole wonders what sort of topsy-turvy universe we now live in where Gary Lineker is suddenly being called a “political activist” by a Conservative MP? Our favourite big-eared football pundit has found himself in a war of words with the Sun newspaper after wading into the controversy over the age of the refugee children granted entry into Britain from Calais.

Pictures published earlier this week in the right-wing press prompted speculation over the migrants' “true age”, and a Tory MP even went as far as suggesting that these children should have their age verified by dental X-rays. All of which leaves your poor Mole with a deeply furrowed brow. But luckily the British Dental Association was on hand to condemn the idea as unethical, inaccurate and inappropriate. Phew. Thank God for dentists.

Back to old Big Ears, sorry, Saint Gary, who on Wednesday tweeted his outrage over the Murdoch-owned newspaper’s scaremongering coverage of the story. He smacked down the ex-English Defence League leader, Tommy Robinson, in a single tweet, calling him a “racist idiot”, and went on to defend his right to express his opinions freely on his feed.

The Sun hit back in traditional form, calling for Lineker to be ousted from his job as host of the BBC’s Match of the Day. The headline they chose? “Out on his ears”, of course, referring to the sporting hero’s most notable assets. In the article, the tabloid lays into Lineker, branding him a “leftie luvvie” and “jug-eared”. The article attacked him for describing those querying the age of the young migrants as “hideously racist” and suggested he had breached BBC guidelines on impartiality.

All of which has prompted calls for a boycott of the Sun and an outpouring of support for Lineker on Twitter. His fellow football hero Stan Collymore waded in, tweeting that he was on “Team Lineker”. Leading the charge against the Murdoch-owned title was the close ally of Labour leader Jeremy Corbyn and former Channel 4 News economics editor, Paul Mason, who tweeted:

Lineker, who is not accustomed to finding himself at the centre of such highly politicised arguments on social media, responded with typical good humour, saying he had received a bit of a “spanking”.

All of which leaves the Mole with renewed respect for Lineker and an uncharacteristic desire to watch this weekend’s Match of the Day to see if any trace of his new activist persona might surface.


I'm a mole, innit.