Heatwaves have long been part of the Tour but temperatures now are pushing the riders to limit of human endurance The Tour de France and the heat of the midday sun are old bedfellows, going back long before an era when the biggest catastrophe of the Tour’s opening week was a major fault in the Visma team bus’s air conditioning. Flip back 50 years to my favourite Tour read, the late Geoffrey Nicholson’s The Great Bike Race, and we find the doyen of cycling writers discussing a Tour that began in