When is a pedal-bike so electronically-assisted and fast that it's no longer a pedal-bike? It's the subject of debate in the world's leading cycling countries Denmark and Holland, where many of the new bikes sold are now 'pedal electric cycles' or 'pedelecs' for short. The Dutch have decided to be strict with pedelecs. But the Danes have gone the other way. In Copenhagen, John Laurenson reports.