[kropotkin thinks...] - 2017 Barcelona MotoGP Saturday Notes: A Primer On Asphalt, An

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Sunday at Barcelona is going to be a war of attrition. Everything is conspiring against the riders, and most especially the tires. Temperatures are expected to rise even higher than they were on Saturday, when air temperatures hit over 32°C, and track temperatures climbed to 55°C and above. Those are punishing temperatures in which to race a MotoGP bike, especially at Montmelo, where the heat gets trapped in the bowl of hills which holds the circuit.

Then there's the tires. There is much complaining about the lack of grip and the fact that grip drops off a cliff after seven or eight laps. It would be more accurate to blame that on the track, though: the Circuit de Barcelona-Catalunya has not been resurfaced in twelve or thirteen years, and is very heavily used, both by bikes and by cars. That has created a surface which is both too smooth to provide grip, while simultaneously being incredibly abrasive.

That sounds contradictory, so when Michelin boss Nicolas Goubert spoke to a group of journalists on Friday night, I asked him to explain. The Frenchman explained that grip and abrasiveness came from two different parts of the surface. Asphalt (or rather, a road or racing surface) consists two parts: binder and aggregate. Aggregate is basically small stones, specially selected for size and shape. Binder is usually a special formulation of bitumen, often containing other ingredients.