When the round four of 2015 MotoGP began at Jerez, track temperatures were a toasty 122 degrees (F), causing slick conditions.
These high temps challenged the riders and Bridgestone spec tires throughout free practice and qualifying, but things cooled considerably for the 27-lap race at the 2.75-mile Spanish circuit, the track temps hovering around 100 degrees (F).
These cooler temperatures assisted Movistar Yamaha MotoGP YZR-M1 pilot Jorge Lorenzo as he claimed his first win of 2015 MotoGP. En route to the flag-to-flag victory, the two-time MotoGP Champion Lorenzo also set a new Circuit Record, Best Lap Record and also completed the race in record time, beating the previous mark by 20 seconds.
Joining Lorenzo on the podium was the reigning MotoGP Champion Marc Marquez, the Repsol Honda RC213V pilot who battled through pain due to breaking his finger the week before while dirt-track training, and the current points leader, Lorenzo’s teammate Valentino Rossi, respectively.
Following is some Jerez MotoGP analysis through a Q&A with Bridgestone’s Manager of Tire Development, Shinji Aoki.
Q. The hard compound front tire was used extensively at Jerez, with 23 riders selecting this option for the race. What was it about this specification of tire that made it such a popular race choice?
Shinji Aoki says; “Jerez is a circuit that requires high levels of stability and feel from the front of the bike. At the same time, the grip level of the tarmac diminishes significantly in hot temperatures so finding the optimal combination of grip and stability is really important for the riders.
“Our latest specification of hard front slick was designed to offer the same level of stability as the previous spec, but with better grip and this year was the first time riders had access to this new hard front slick at Jerez as we only introduced it into our allocation late last year.
“I am very happy with how it performed as the riders were able to lap consistently at a very fast pace using this new hard compound front slick, and even in very high temperatures they felt they had good grip and stability from the front-end of the bike.”
Q. Temperatures were considerably cooler in the race than they were for FP4 and qualifying. What effect did this have on tire performance, and did it cause any riders to reconsider their race tire choice?
Shinji Aoki says: “The lower temperatures on race day meant that there was more grip on offer from the tarmac, allowing the riders to get maximum performance out of their tires. As a result the pace shown during the race was really impressive. We were confident that we would beat the qualifying and race lap records, as well as the overall race time record this year, but to beat the records with the margins that we did was astounding.
“With temperatures for the race not as high as they were the day before, it meant the track wasn’t as greasy, so the riders could lap at a strong pace throughout the race. In terms of how the cooler temperatures influenced tire choice for the race, it didn’t have a great effect at all. The majority of riders still used the same tire combinations that they would’ve used in hotter conditions as they were able to assess the performance of the different tyre combinations in the cooler morning sessions on Friday and Saturday.”
Q. So, even if track temperatures were just as hot for the race on as they were on Saturday, you don’t think many factory Honda and Yamaha riders would have selected the hard compound rear slick? Why is that?
Shinji Aoki says: “The asymmetric hard rear slick we offered this year used the same compounds as 2014, yet it wasn’t as popular as last year, which we believe is mainly due to the deteriorating grip level of the Jerez tarmac. The grip is quite poor in hot conditions, but even in cooler temperatures, the riders felt the grip was worse than last year.
“Although the hard rear slick was very consistent, the riders needed the rear tyre option that offered the highest amount of grip to compensate for the poor track surface to reduce the amount of spinning from the rear. This is what made the medium compound rear the preferred choice for the factory riders, regardless of track temperature. The fact that this option also provided good durability made its appeal even greater at Jerez.”