Considering their incidence in the population, cyclists crop up an awful lot in traffic proposals. Ken Livingstone is considering mandatory numberplates for bikes in London. There were noises not so long ago about obliging cyclists to use cycle paths. The most recent and most absurd proposal is for cyclists to sound a little bell, continually, to warn pedestrians of their approach. Cyclists found not using a bell under this scheme would be liable for a fine between £30 and £2,500, or - for persistent, unrepentant non-bell-ringers - two years in prison.