For us mere mortals, the prospect of cycling 124 miles (200km) in one day is challenge enough.
But the Tour de France’s world-class cyclists are forced to cover hundreds of miles of ground – much of it steep and unforgiving alpine terrain – almost every day for three weeks.
The physical fitness and mental toughness required to even attempt such a feat is almost incomprehensible for anyone whose body and mind has not been fortified by years of dedicated training.