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

Getty
Show Hide image

How Theresa May laid a trap for herself on the immigration target

When Home Secretary, she insisted on keeping foreign students in the figures – causing a headache for herself today.

When Home Secretary, Theresa May insisted that foreign students should continue to be counted in the overall immigration figures. Some cabinet colleagues, including then Business Secretary Vince Cable and Chancellor George Osborne wanted to reverse this. It was economically illiterate. Current ministers, like the Foreign Secretary Boris Johnson, Chancellor Philip Hammond and Home Secretary Amber Rudd, also want foreign students exempted from the total.

David Cameron’s government aimed to cut immigration figures – including overseas students in that aim meant trying to limit one of the UK’s crucial financial resources. They are worth £25bn to the UK economy, and their fees make up 14 per cent of total university income. And the impact is not just financial – welcoming foreign students is diplomatically and culturally key to Britain’s reputation and its relationship with the rest of the world too. Even more important now Brexit is on its way.

But they stayed in the figures – a situation that, along with counterproductive visa restrictions also introduced by May’s old department, put a lot of foreign students off studying here. For example, there has been a 44 per cent decrease in the number of Indian students coming to Britain to study in the last five years.

Now May’s stubbornness on the migration figures appears to have caught up with her. The Times has revealed that the Prime Minister is ready to “soften her longstanding opposition to taking foreign students out of immigration totals”. It reports that she will offer to change the way the numbers are calculated.

Why the u-turn? No 10 says the concession is to ensure the Higher and Research Bill, key university legislation, can pass due to a Lords amendment urging the government not to count students as “long-term migrants” for “public policy purposes”.

But it will also be a factor in May’s manifesto pledge (and continuation of Cameron’s promise) to cut immigration to the “tens of thousands”. Until today, ministers had been unclear about whether this would be in the manifesto.

Now her u-turn on student figures is being seized upon by opposition parties as “massaging” the migration figures to meet her target. An accusation for which May only has herself, and her steadfast politicising of immigration, to blame.

Anoosh Chakelian is senior writer at the New Statesman.

0800 7318496