Saturday MotoGP Summary at Catalunya: A Primer on Asphalt, And A War of Attrition

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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.

Asphalt Primer

When new asphalt is laid, the stones which make up the aggregate have a very rough surface, and this roughness is what tire rubber binds to and generates grip. Binder fills the gaps between the aggregate, providing a smooth surface which does not stress the tires too much.

As asphalt ages, the bitumen or binder is gradually washed away, leaving large gaps between the stones in the aggregate. This makes the track extremely abrasive, and causes tires to wear very quickly.

And when a track surface sees a lot of use – especially from larger, heavier vehicles with fat tires such as cars – the surface roughness of the individual stones which make up the aggregate gets worn away, the stones becoming polished and very smooth. There is no microsurface roughness for tires to grab onto.

That’s why an old, well-used surface can be both extremely abrasive, and yet offer very little grip. And that is exactly what has happened at Barcelona. Michelin – or any other tire maker – could build a tire to extract more grip from the polished aggregate, but to do so they would have to use very soft rubber.

If they used soft rubber, the tires would be destroyed in a couple of laps, torn apart by the gaps between the aggregate left by the missing bitumen.

And so we are left with a likely war of attrition on Sunday. The race will be won by the rider who stresses their tires least in the opening laps, and can make them last for as long as possible.

That favors a couple of factors: riders who are light; riders who are smooth in both their throttle control and bike movements; and riders who are experienced.

It’s Race Pace that Counts

A troll through the MotoGP FP4 analysis timesheets suggests a couple of riders are likely to be strong. Dani Pedrosa has race pace half a second or so quicker than anyone else on the grid. Jorge Lorenzo has pretty strong pace too, the best of the rest but no match for Pedrosa.

Behind Lorenzo, Andrea Dovizioso and Valentino Rossi stand out, though Rossi was trying to downplay his chances. “The pace is not fantastic,” he said in his opening statements.

When I pointed out that in terms of race pace in FP4, he was third fastest, he acknowledged things were not that bad. “The pace is nothing fantastic because have a lot of riders similar, except Pedrosa that is faster. But like you said, it’s not so bad.”

One had a strong sense that Rossi was indulging in a spot of sandbagging. His problem, of course, is that he starts from thirteenth, after missing out on Q2 during FP3, then again coming up just short during Q1.

The contrast between Rossi and his teammate Maverick Viñales was striking. Viñales exuded exasperation on Saturday, unable to understand what was happening to his bike.

The front felt pretty good, he explained, but the rear was moving around under acceleration and under braking. From the outside, it looked like he was riding a Honda rather than a Yamaha.

“I have no grip and the bike is jumping,” Viñales said. It was different to Jerez, where he had no grip or feeling at the front. Here, the problems were all at the rear.

Youthful Aggression Versus Maturity and Experience

Andrea Dovizioso offered an interesting insight into the difference between the two Movistar Yamaha teammates.

“Maverick is struggling a little bit more, but I think he doesn’t have the same experience as Valentino, about everything with the Yamaha, and I think that Maverick and Valentino approach the weekend in a different way,” Dovizioso reflected.

“Maverick is in the best situation, he wants to win, he’s really aggressive and when you find difficult conditions like we have at this track, you have a shock, and you can work in a bad way sometimes, you are too aggressive. Valentino works slowly, and in the end, his pace in FP4 is really good. So I think it’s about experience.”

Pol Espargaro also pointed to Rossi’s experience. The rear was spinning up under acceleration, especially when the bike was still leaned over, Espargaro explained, and that was what determined tire wear.

“We need to try to control for tomorrow, because I think it’s going to be a key of the race. For me, the guy who is going to manage better the tires is going to win the race and I think Vale is good on that.”

Dovizioso may have been pointing to Rossi, but he himself was confident of a good result. “Unfortunately we couldn’t make a really fast lap time in FP4, because we started with a used tire and it wasn’t the best decision,” the Italian told us.

“I believe we have a chance to really fight tomorrow for the podium. Unfortunately I didn’t make a perfect lap in the qualifying, but my feeling with the soft tire wasn’t good. Also in the test my feeling with the soft tire wasn’t very good. So regarding that, I’m happy about the lap time that I did at the end. The position is not the best, but with a good start, I think we have for sure a chance to fight for the podium.”

Honda Rampage

All things considered, the race on Sunday looks like Dani Pedrosa’s to lose. In similar conditions at Jerez, the Spaniard dominated, as he did on Saturday in Barcelona. The battle for second behind Pedrosa should get interesting, with Dovizioso, Lorenzo, and Rossi all capable of running a strong pace.

The big question for Rossi starting in thirteenth is how well he can fight his way through to the front. Once the tires drop off on lap six or seven, Rossi should still have enough tire left get through to the podium chase. The big question is just how far away the leaders are by then.

The big unknown is just where Marc Márquez fits into the scheme of things. His race pace is relatively unknown, as he seemed incapable of staying on the bike on Saturday.

After falling off once in Friday, Márquez hit the deck four times on Saturday, including two crashes during qualifying. Was he trying just a little too hard, perhaps?

“Today, especially in the afternoon, the track was critical,” Márquez said. “But I didn’t feel really bad. Okay, I crashed many times, but the qualifying practice crashes I was too aggressive. The track was not ready to be like this and I didn’t understand well, pushed too much. That was the mistake.”

The issue Márquez has, along with many other riders, is how to manage the front end of the bike. Márquez used the hardest of the three options, but it was not enough for him to stay upright. The hard tire is a necessity if a rider is to reach the end of the race. But it brings the risk of crashing with it.

Shake Up Coming

Sunday’s big loser could well be Maverick Viñales. The Spaniard and championship leader has struggled all weekend, illustrated perfectly by his runs in FP4, when he went out on a hard front and medium rear, then a medium front and a hard rear, before reversing that back again at the end of the session.

Viñales is looking for a solution, but at the moment, there simply doesn’t appear to be one.

Should Viñales finish well down the order, that would open the championship up again. The events of Saturday prove once again that MotoGP is nothing if not unpredictable.

You get the distinct feeling that on Sunday, just about anything could happen.

Photo: KTM

This article was originally published on MotoMatters, and is republished here on Asphalt & Rubber with permission by the author.