Olympic champions and modern tire technology
Jens Fiedler, Rene Wolf, and Stefan Nimke have fond memories of the Athens Olympics four years ago, when the three of them were the golden boys of the German cycling sprint team. “Not least thanks to cutting-edge tire technology”, confirms Detlef Uibel of the German Cycling Federation (BDR) and German national coach for sprint track cycling. He’s confident that whoever has the advantage here will also be standing on the winners’ podium at the Beijing Olympics. Which is why it is necessary to continually reinvent the bicycle tire, so to speak.
More speed for less effort
And now there’s been another revolutionary development in bicycle tires. German tire giant Continental, based in Hanover, has succeeded in reducing rolling resistance by 26 percent, thanks to a novel tire technology. This means that the rider has to spend far less energy. Anyone who’s ever cycled up a steep incline, and especially professional cyclists, will appreciate what an advantage this can be. As Wolfgang Arenz, a Continental applications technician, explains, this advance has been made possible by “expertise and high-tech raw materials.” And the decisive contribution here comes from the fillers specialists of Evonik Industries.
Multilayered: Modern bicycle tires consist of a triple layered carcass structure and a Vectran breaker, topped by a tread.
Continental has succeeded, by optimal combination of the properties of carbon black, silica, and silane, in developing tires of considerably lower rolling resistance. This allows higher speeds to be achieved for the same energy input, and also improves the grip of the tire to the surface, which is particularly important when the track is wet. For this, silica as well as carbon black must be bonded to the rubber. “Our organosilanes, such as Evergreen Si 69®, make this possible,” says Bernhard Schwaiger, an Evonik technical service specialist. “This is yet another result of our decades of experience as a leading producer of tire fillers.”
Focus on weight
The cyclist’s heart beats faster when he thinks of the weight of his tires. Reducing tire weight is high on his wish list, but for tire producers and suppliers of raw materials this is a major challenge. “As for materials,” says Continental’s Arenz, “we’re pushing the envelope.” The treads alone, which are mainly responsible for the increase in speed, weigh about 100 grams. The fillers, consisting of 15 grams of carbon black, 15 grams of silica, and 1.5 grams of the organosilane that binds the silica to the rubber, account for about a third of this weight. Top-notch tires weigh no more than 160 grams; every gram in excess of this puts professional cyclists at a tangible disadvantage to their competitors. Rolling resistance and wet grip are also important. But for indoor track cycling, the Olympic category with the greatest promise of medals, these factors play a rather minor role. “The less energy my riders expend, the greater their chances of a medal,” says Uibel.
The three Evonik products for the tire industry: (from left) ULTRASIL® silica, CORAX® carbon black, and the organosilane Si 69®.
Cutting-edge system
What all high-end tires from Continental have in common is the cutting-edge “Black Chili” compound system based on the Evonik products CORAX® carbon black, ULTRASIL® silica, and the above mentioned Evergreen Si 69®. Continental tunes tires, as it were, with Black Chili, which contains carbon black particles whose form and surface properties have been optimized for use in cycling. These high-tech tires already have the edge over their competitors: Black Chili tires offer 26 percent less rolling resistance, a 30 percent higher tire-to-road friction coefficient for maximum roadholding and a good “feel”, and 5 percent higher mileage, regardless of the type of bike. For Beijing, this is the stuff that makes Olympic champions. And what does the future hold? Schwaiger and Arenz both agree on one thing: “The goals will stay pretty much the same: keeping weight low, while achieving even less rolling resistance and therefore higher speed.”
