Paris - Along the winding roads through green countryside, up the steep mountain climbs and through the scenic villages, they are the one constant in the Tour de France - the fans cheering on riders from the side of the track.

While most fans watch enviously from home as the stunning French scenery rolls by on their television, some lucky or local spectators get to watch the world's greatest cycling race firsthand.

The Tour is the world's only major sporting event free for spectators and it brings out all sorts.

There are the die-hard cycling fans desperate for a brief glimpse of their heroes, the families turning a trackside day into a picnic, the older enthusiasts back for another year, the tourists, the drinkers, the exhibitionists dressed up in French flags or dressed down in swimsuits.

With 21 stages over 3 480 kilometres, there is plenty of space to stretch out in - except for the packed daily finish lines.

And with the riders whizzing past in a brief blur, there's also plenty of time to kill, and many fans use it to try and make sure they are seen - by both the riders and maybe the television cameras.

This year some made signs to wave at the riders, others let off colourful flares and many dressed up in all manner of costumes, with one bold group of men even urging on the cyclists while wearing "mankini" swimsuits popularised by the movie "Borat".

Slovakian rider Peter Sagan even found time to autograph his autobiography for a fan as he rode during a stage.

As a heatwave descended over the Tour this week, spectators have used umbrellas to avoid sunburn while others employed inflatable pools to beat the heat.

Drinking lots of water is recommended to keep hydrated under the beating sun, but many seem to prefer beer or wine.

Unlike most sports, Tour spectators can choose their preferred terrain.

Some pick the long flat stretches through farmlands, lounging on haybales.

Others prefer mountains, where normally isolated cliffs are briefly overrun with festivities.

And of course city-dwellers don't miss out - this year the Tour started in Brussels and will come to an end with much fanfare in Paris on Sunday.

However there is one rule that applies to all Tour spectators: "Don't run alongside the riders."