Traditionally the first part of the final stage is treated like a celebration. At some point during a three week grand tour, everyone is going to suffer or struggle at some point. They've dragged their bodies over the Pyrenees and the Alps, through the heat and the rain, come back from mechanicals and flat tires, dealt with crazed fans and road hazards, some of the riders have battled through illness, dehydration, or bonking... After kicking the ***** out of each other for three weeks, it's a chance for them to celebrate that they have finally made it. While some riders focus on the general classification standings, stage wins, or winning a jersey, many of the riders just struggle to finish within the time cut and keep going another day. This is a chance to enjoy the Tour, rather than surviving it.
That all changes once the Eiffel Tower is within sight. There's still a final stage to be won, and many years the green jersey is still to be decided. Traditionally the competition resumes once the Tower is in sight, and then the engines get fired up for one final showdown in to Paris.
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The rider in my avatar is David Etxebarria, not me.