US GP: Bridgestone debrief

Bridgestone slick compounds used: Front: Medium, Hard Rear: Medium, Hard The eighth round of the championship saw Dani Pedrosa take his and Repsol Honda's first victory on Bridgestone tyres, and their first win of the season. Valentino Rossi ...

Bridgestone slick compounds used:
Front: Medium, Hard
Rear: Medium, Hard

The eighth round of the championship saw Dani Pedrosa take his and Repsol Honda's first victory on Bridgestone tyres, and their first win of the season. Valentino Rossi finished second to extend his lead in the overall standings, ahead of polesitter Jorge Lorenzo and Casey Stoner. The shortest circuit on the calendar is a tricky one for bikes, riders and tyres, as became apparent during the frantic closing minutes of Saturday's hour-long qualifying session, when traditionally the riders are pushing hardest and the fastest times are set.

Q&A with Tohru Ubukata - Bridgestone Motorsport - Manager, Motorcycle Race Tyre Development

What were the challenges faced at the United States GP?

Laguna Seca has some unique challenges. It is a short circuit with only 11 corners which means that the Bridgestone slicks covered less distance in a lap and therefore relatively more laps were needed for them to reach optimum temperature. This was an especially important factor during the qualifying session.

The landform of the circuit was also a challenge as some corners are uphill and others downhill which produces variations in the weight transfer of the bikes. Tyres naturally generate peak grip when they are properly loaded, but in turns three and ten in particular it was harder for the riders to load their rear tyres because the corners are downhill, meaning the weight transfer is towards the front of the bike and away from the rear tyre, giving less rear grip.

There are fewer right-handed corners at Laguna which meant that the right shoulder of each tyre was not used as much throughout the lap. The right shoulder also cooled between right-handers, especially as the ambient temperature was relatively low, so ensuring the tyres were properly up to temperature was crucial for the riders.

Jorge and Casey crashed during the qualifying session on their first quick laps out of the pits on new rear slicks. They didn't get enough temperature in their tyres before their attacking laps, as they explained in the post-qualifying press conference. This meant that their tyres were operating at a lower temperature, especially on the right side, and this was a major contributor to their falls.

There were some calls for asymmetric tyres during the weekend. What can you say about this?

The temperature data we collected from last year's race allowed us to predict that the temperature differential between the left and right shoulders would be only a few degrees Celsius, and we based our tyre compound selection for the weekend on this data. This year's tyres are designed with a much wider temperature operating range than last year's so we chose to bring the single compound to Laguna because we believed they would be suitable for the conditions.

Our temperature prediction was correct, and the difference between the shoulders of the rear tyres was very similar to that experienced in Mugello and Assen, where we also used single compound tyres. I support our tyre choice this weekend, but of course as part of our continual development process we will carefully analyse all our data from the weekend and consider asymmetric tyres for Laguna next year.

-credit: bridgestone

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About this article
Series MotoGP
Drivers Valentino Rossi , Jorge Lorenzo , Casey Stoner , Dani Pedrosa