Bike Anti-Porn - When Things Go Wrong

but if the opposite is true like the article says, why don't they ride fat tyres in the Tour?

Bollocks article.

Not bollocks, but they have ignored the dominance of aerodynamics at high speeds. Total resistance to forward motion is the sum of rolling resistance and aerodynamic drag (+some minor bits and pieces), and the ideal balance depends on the target speed, since drag rises as the square of speed while rolling resistance is essentially constant. In fact, there is a move towards slightly wider tyres in pro road racing, but only a couple of millimetres.

Part of the reason for the origin and persistence of the fallacy that narrow tyres roll faster is that casing stress rises with tyre pressure and sectional radius, so for a given stress one must either reduce pressure (and thus raise rolling resistance) or increase casing thickness (again raising rolling resistance) if the casing section is increased. Also, historically, only narrow 'racing' tyres were made with the thin treads and casings which give low rolling resistance. The key phrase in the article is " All other factors being equal" - the fact is, they are seldom equal since people who want wide tyres usually also want long lasting treads and highly resistant casings. If you cut tyres of different sections from the same cloth, and apply the same tread band, wider tyres will have lower rolling resistance, even if you lower the pressure in the bigger tyres to maintain constant casing stress.