Tyre compound selection featured heavily during the 80th edition of the Dutch TT at Assen. Throughout the weekend riders were lapping competitively on each specification, and the race provided a direct comparison between the extra edge grip of the...
Tyre compound selection featured heavily during the 80th edition of the Dutch TT at Assen. Throughout the weekend riders were lapping competitively on each specification, and the race provided a direct comparison between the extra edge grip of the softer rear slick option and the additional traction of the harder option. Jorge Lorenzo took his fourth win of the season using the hard option, after coming under pressure in the early stages from Dani Pedrosa and Casey Stoner, both of whom were using the softer rear tyre. The circuit was slightly modified this season in the Ruskenhoek corner, and whilst the circuit length was shortened by only 13 metres, the new lap record set by Dani Pedrosa was two seconds faster. The track temperature was high, reaching 47 degrees Celsius, and the weather was fine throughout the weekend maximising the riders' dry running time.
Q&A with Tohru Ubukata - Manager, Bridgestone Motorcycle Tyre Development Department
The riders' rear tyre choices were mixed in the race; why was this?
"Last year we brought soft and medium tyres to Assen, and almost all riders used the medium compound for its extra durability on the right side. This year we brought asymmetric tyres to Assen, and also went one compound step harder as part of our process of continual development and improvement. This means that this year the riders could choose the medium or the hard compound rears for added durability in the right shoulder, whilst the soft compound rubber in the left shoulders retained warm-up performance and edge grip on the left side.
"Our objective for tyre development in the single tyre era has always been to increase their temperature operating range; that is the range of conditions and track temperatures in which each specification can perform well. Indeed, we were doing this even before our appointment as the single supplier. Our achievements in this area mean that we now have a good overlap of performance between our different tyre compounds, and as we saw in particular this weekend both the medium and the hard asymmetric rear tyres offered similar levels of performance.
"Tyre choice for the race therefore came down to rider preference and machine setup. Jorge was able to extract maximum performance from the hard rear and benefit from its increased durability, whereas Dani and Casey were able to use the softer option and benefit from its increased edge grip and initial performance in the early stages of the race. Some riders and bikes use the tyres harder than others and generate higher tyre temperatures so we recommend either one of our tyre options based upon attaining the optimum tyre temperature for each rider, machine and tyre package."
There was no difference in front tyre choice however; what can you say about this?
"Firstly, the front tyre options we brought to Assen were softer than the rear: we selected the soft and medium fronts whereas the rears were our medium and hard compounds. If the temperature was cooler, some riders may have used the soft front for its extra edge grip, but as it was with a track temperature in the race of 47 degrees Celsius, the harder front tyre provided greater braking stability and more consistent front-end feeling for the riders."
The modification to the circuit at the Ruskenhoek corner improved laptimes by two seconds: did it have any impact from a tyre perspective?
"The change to the circuit layout didn't impact upon tyre shoulder performance as although corner speed was higher through Ruskenhoek as a result, loads were not excessive and tyre temperatures were still well within operating range. I can say though that the affect it did have was under braking into the right hander after, Stekkenwal. Carrying more speed through Ruskenhoek meant heavier braking into Stekkenwal which created more load on the centre of the front tyre, which was another contributing factor to all riders using the harder front for the race."