There could be nothing less offensive as a mode of transport than a man on a push bike - or could there?

He causes no pollution and produces no noise. He takes up little road space. He breathes in fresh air (if there are not too many cars) and keeps fit.

Yet cyclists are often vilified by motorists as the biggest menace on the roads. People walking on pavements tend not to like them much either.

Why is this? It's partly the changing nature of Cycling.

Fifty years ago it was an accepted mode of transportation, used by millions of people to get to work or to nip round to the shops.

The growth in car ownership made many people switch to something that required no physical effort and which was faster.

This in turn made biking more dangerous, pushing cyclists off the roads - sometimes literally.

It was mountain biking that caused a new surge of interest and a more aggressive attitude as riders tried to reclaim the streets.

A new breed of aggressive young cyclists, in stark contrast to the old law-abiding variety, began to ignore traffic regulations such as one-way street and red lights.

Mountain bikes made it easier for cyclists to mount the pavements, which they did with increasing frequency.

Police, who used to tick off and even prosecute cyclists if they so much as failed to display the obligatory rear reflector, stopped taking much of an interest as they had more important things to do.

I hold no brief for Lycra louts who cycle through shopping centres, scattering pedestrians and shouting obscenities at them. Nor do I, for the most part, break the law by ignoring signs and lights.

But the road rage directed against cyclists is out of all proportion to crimes they commit.

I have never seen a rider knock anyone over and most years no one is killed by cyclists. By contrast, more than 1,000 pedestrians are killed by cars and hundreds of bike riders.

People correctly complain when cyclists break the law and ride along the seafront at Hove, yet they take no notice of the increasing number of cars using it as a highway.

The trouble is that bikes do not fit in anywhere. They are too narrow to take up a full lane in the road. They are silent so they make pedestrians jump when passing close to them.

Yet, officially, cycling is a good thing. We're all exhorted by councils and the Government to get out of cars and on to bikes. Every time we do, we contribute a bit to making overall travel easier and more peaceful.

There are more bikes than cars in this country yet they are used far less. Whether through fear or laziness, most people leave their machines in lofts and garages rather than ride them regularly.

This doesn't apply in many other countries. Everyone knows how keen the Dutch are on cycling in their small flat country.

So are the Danes and the Germans. They own more cars than we do but use them less and get on their bikes more.

All these countries have a network of bike lanes that puts Britain's to shame. Improvements are being made here - but slowly.

It took years for the seafront cycle lane in Brighton and Hove to be approved and it is the most popular one in Sussex, despite being bumpy and built in the wrong place.

Sustrans, the cycle track-building charity, was given a £42 million millennium grant by the National Lottery to build a countrywide network of paths.

The Cuckoo Trail at Polegate and the Centurion Way at Chichester are among its proudest achievements.

Yet Sustrans has had immense difficulties getting approval in other areas, such as Seaford, because for some strange reason people do not want cyclists passing their homes.

When I carried out research recently for a book on bikes (Cycling Sussex, Pomegranate Press £9.99), it became clear how patchy the current network of paths and tracks is in Sussex.

You can ride all the way from Lewes to Brighton along special lanes but as soon as you reach the difficult Vogue Gyratory the tracks abruptly disappear.

A cycle path has been built alongside the A23 from Brighton to Crawley. Yet it is so close to the canyon of cars in some places, and takes such unnecessary deviations in others, that few people ever use it.

It will take time and major investment to create a cycle network that will encourage people back on to their bikes.

The alternative is to do little or nothing and witness a slow but steady decline in two-wheeled transport. It's called a vicious cycle.