Design stories: Specialized S-Works Turbo tyre

When Etixx-QuickStep rolled out for the Tour of Flanders in April, the Belgian super team knew exactly what to expect, from their tyres, at least.
Rain can reduce the Flandrian Monument to a lottery and for Patrick Lefevre’s outfit, a performance for De Ronde is more important than for any other, hence the importance to the team of men like mechanic Kurt Roose, pictured above.
EQS had begun work with Specialized to develop a new compound for the flagship S-Works Turbo tyre in 2012, and 1 subscribers will be familiar with the story of the final pre-Ronde test on the Steenbeekdries in January (issue 57).
The tyre compound on which EQS (and its Omega Pharma-QucikStep predecessor) have raced for the last two seasons is the brain child of Wolfgang Arenz, a specialist in the field.

New variants of synthetic rubbers from which tyre compounds are created come to market continually. For this reason, Arenz explains, the compound used by Specialized in its Turbo tyre, dubbed Gripton, is continually evolving.
Feedback from riders such as Zdenek Stybar and Nicolas Maes is gathered for every iteration of the compound during the development phase and is the factor that decides whether the tyre goes into production, or whether Arenz returns to his laboratory for further development.
In which areas is feedback most valuable?
“We are looking for feedback on road feel and grip,” Arenz explains. “These characteristics cannot be lab tested. Road feel is the sensation that comes through the handlebars.
“By adjusting damping and hardness, we control vibrations and achieve stable direct steering input to the road at the same time. With EQS’ emphasis on high speed sprinting and time trials, rolling resistance is an important performance measure, too.”
Additional testing and development work is completed for what Aertz describes as “special applications”: the Spring Classics, time trials, and high mountain stages.
Work centres on the precise mix of fillers, oils, and polymers. “How can we use those to further reduce rolling resistance, increase drag or minimise wear?” Arenz asks, rhetorically.

He places equal emphasis on each quality. The tyre technician’s greatest challenge is to balance often conflicting targets. A compound must be fully developed in every aspect to be successful.
“What good is a fast, but slippery time-trial tyre?” Arenz asks. “What good is a tyre that is grippy on wet mountain descents, but leaves you wasting energy defending the lead on the valley floor?”
The Gripton compound is used in both tubular and clincher incarnations of the S-Works Turbo tyre.
Even if the performance gap between tubular and clincher is narrowing, the traditionally conservative road market might be slow to recognise it; witness the slow adoption of disc brakes, a technology de rigueur in mountain biking for a decade.
The peloton, and the consumer market it influences, has been quicker to adapt the new mantra that wider tyres are faster. Arenz says Etixx-QuickStep was hip to the new groove, adopting 24mm tyres as early as 2012, and now routinely using 26mm Turbos, too.
He can be expected to remain at the forefront of tyre technology, routinely assessing the new influx of chemicals to the synthetic rubber market and testing his prototypes with Lefevre’s riders. Specialized has made little secret of its satifcation in gaining Aertz’s signature. In the matter of tyre development, the technican’s input is every bit as important as the rider’s.

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