Why is it a universal truth that cyclists hate losing momentum? If we were walking, we'd be happy to stop and then start strolling again. But put us on a bike and we're crazy mustangs.

I guess it's because we know instinctively that it's harder work picking up speed again on a bike than when walking. But exactly how much harder is it? The answer from Chris Juden, technical officer of the Cyclists' Touring Club, is a revelation.

Well, riding a bike at a steady pace takes as much energy as walking at a quarter of that speed. So cycling at 12mph is the same as walking at 3mph. Which explains why most people are as happy to cycle four miles to work as they are to walk one. Cycling at this speed on an uninterrupted four-mile journey, lasting 20 minutes, would result in a total energy expenditure of 90 kilojoules.

Every time a cyclist or pedestrian stops, they lose kinetic energy and have to work harder on starting off to accelerate and restore that kinetic energy. Now — and this is the maths bit — kinetic energy is proportional to mass multiplied by speed squared. This means to reach a steady cycling speed four times that of walking, requires a 16-fold increase in energy (plus about 25% more for the added mass of the bike).

So here it is: the cyclist has to expend about 20 times as much energy as a pedestrian to reach his normal journey speed again. This energy could have carried the cyclist a great deal further had no stop been made. In fact one stop-start is the equivalent to cycling an extra 100 metres while a pedestrian can stop-start and expend no more energy than it takes to walk a couple of steps.

And if you've ever wondered why children riding bikes have a natural disregard for road markings, this might be part of the answer. They also know that bikes are harder to control at low speed and so will keep going at all costs.

"This is not a peculiar cussedness of cyclists," says Juden. "Let anyone ride a bike and they immediately discover that stopping is a grievous waste of hard-earned momentum."

For more information on the Cyclists' Touring Club, go to http://www.ctc.org.uk