MotoMatters.com | Kropotkin Thinks

Bridgestone today issued its customary post-race debrief with tire development boss Shinji Aoki. In this edition, Aoki discusses the performance of the asymmetric front tire, and why it was the unanimous choice among the riders this year, and explains how the location of Phillip Island makes selecting the right rear tires a difficult task.

Australian MotoGP™ debrief with Shinji Aoki
Tuesday, October 20 2015

Bridgestone slick compounds: Front: Extra-soft, Asymmetric & Soft; Rear: Soft, Medium & Hard (Asymmetric)
Bridgestone wet tyre compounds: Soft (Main) & Hard (Alternative)

Round sixteen of the 2015 MotoGP™ season was the Australian Grand Prix at Phillip Island Circuit, where Repsol Honda Team’s Marc Marquez won one of the most exciting contests in years ahead of Jorge Lorenzo and Andrea Iannone who claimed the remaining rostrum positions.

The weather at Phillip Island was unusually stable over the race weekend with all sessions being declared dry, including Sunday’s race where the track temperature remained steady in the high thirty-degrees Celsius range. A new overall race time record was set by Marquez, beating the old mark by thirteen seconds and the reigning champion also managed to set the quickest lap time of the race, clocking a 1’29.280 on the very last lap.

Q&A with Shinji Aoki – Manager, Bridgestone Motorcycle Tyre Development Department

For this year’s Australian Grand Prix, Bridgestone developed a brand new asymmetric front slick. How did this new asymmetric front slick differ from the one that made its debut at Phillip Island last year?

“The asymmetric front slick we developed for this year’s Australian Grand Prix used the same rubber compounds as last year’s version, but this year we changed the areas in which the two compound zones were located on the tyre. Last year’s asymmetric front slick had the extra-soft compound rubber located only on the right shoulder of the tyre, while the centre and left shoulders were comprised of the soft compound rubber. For this year, the extra-soft rubber was used on the right and centre section of the tyre, with the soft compound rubber used only on the left shoulder. At the end of last year’s race, the track temperature dropped significantly which resulted in some riders losing control while braking, so we wanted to avoid a repeat of that situation this year. The change we made this year ensured that the asymmetric front slick had better warm-up performance and braking feel than last year, while still maintaining good cornering stability through the fast left-hand turns. This new development was universally praised by the riders and over the whole weekend we only had one crash in MotoGP across all sessions including the race. I believe our new, safer, asymmetric front slick was a major contributor to this reduction in incidents.”

All of the riders selected the asymmetric front slick for the race, were you surprised that no riders selected the soft compound front slick given that conditions were fine for the race?

“The riders liked that the asymmetric front slick quickly got to its optimum operating temperature, had excellent feel under braking and also provided good durability and stability on the left shoulder of the tyre. Basically, the asymmetric front slick provided all of the advantages of the extra-soft and soft compound front slick combined in one tyre. All these factors made it the unanimous choice for the race, but I think that if temperatures were warmer than they were on Sunday, some riders perhaps would have chosen the soft compound front slick to give them more stability in the braking zones and right-hand turns. However, the combination of safety, performance and control the asymmetric front slick offered convinced the riders it was the best option given the conditions we had on Sunday.”

Only two of the three rear slick options; the soft and medium compound slicks were used over the weekend. Why did the hard compound rear slick remain unused by the factory Honda and Yamaha riders?

“The seaside location of the Phillip Island circuit throws up a lot of possibilities in terms of weather conditions. Ambient temperatures ranging from 10-30°C are possible over the race weekend, so our tyre allocation has to work over a wide range of conditions. The reason the hard compound rear slick wasn’t used this year was that although we had generally fine and mild conditions at Phillip Island last weekend, the track temperatures didn’t reach a high enough level for the hard rear slick to be a viable option. However, just the week before the race ambient temperatures in the Phillip Island area were above 30°C, which would have resulted in track temperatures of around 50°C. In this situation the hard compound rear slick would’ve been a worthwhile option for the factory Honda and Yamaha riders, so we had to include it in our allocation. That said I am very happy with how the soft and medium compound rear slicks worked, as they proved to be very consistent during a gruelling twenty-seven laps of the Phillip Island circuit.”