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 Images.
Show Hide image

Forget gaining £350m a week, Brexit would cost the UK £300m a week

Figures from the government's own Office for Budget Responsibility reveal the negative economic impact Brexit would have. 

Even now, there are some who persist in claiming that Boris Johnson's use of the £350m a week figure was accurate. The UK's gross, as opposed to net EU contribution, is precisely this large, they say. Yet this ignores that Britain's annual rebate (which reduced its overall 2016 contribution to £252m a week) is not "returned" by Brussels but, rather, never leaves Britain to begin with. 

Then there is the £4.1bn that the government received from the EU in public funding, and the £1.5bn allocated directly to British organisations. Fine, the Leavers say, the latter could be better managed by the UK after Brexit (with more for the NHS and less for agriculture).

But this entire discussion ignores that EU withdrawal is set to leave the UK with less, rather than more, to spend. As Carl Emmerson, the deputy director of the Institute for Fiscal Studies, notes in a letter in today's Times: "The bigger picture is that the forecast health of the public finances was downgraded by £15bn per year - or almost £300m per week - as a direct result of the Brexit vote. Not only will we not regain control of £350m weekly as a result of Brexit, we are likely to make a net fiscal loss from it. Those are the numbers and forecasts which the government has adopted. It is perhaps surprising that members of the government are suggesting rather different figures."

The Office for Budget Responsibility forecasts, to which Emmerson refers, are shown below (the £15bn figure appearing in the 2020/21 column).

Some on the right contend that a blitz of tax cuts and deregulation following Brexit would unleash  higher growth. But aside from the deleterious economic and social consequences that could result, there is, as I noted yesterday, no majority in parliament or in the country for this course. 

George Eaton is political editor of the New Statesman.