The bicycle. It's the model of green transport and sales of folding ones that fit on trains are stepping up a gear. But as they multiply, so does rush-hour resentment, as commuters and cyclists come to blows.

Dawn is breaking over one commuter-town train station as the daily grind of travelling to work begins. A City type is easy to pick out at the far end of the London-bound platform - he has forgone formal pinstripes for Lycra shorts and a luminous top.