2011

Pirelli

A Fairy Book Ending

Pirelli Diablo Rosso II
Miller Motorsports Park, Utah
May 31, 2011

By Sam Q. Fleming

Stefania Mascuillo, Pirelli Street Platform Manager – Photo by SPQF

Once upon a time there was a little girl from Lecce, Italy, named Stefania Masciullo. Italy is shaped like a high-heeled boot, and Lecce sits in the heel of the boot, just a short boat ride across the Ionian Sea from Greece. Lecce is a very old city, founded over 2,200 years ago. At one time it was the most powerful city in the deep south of Italy. In the modern age, the charms of Lecce have given way to the modern industrial power of northern Italy.

Stefania lived amidst the engineering and artistic marvels left in Lecce by its previous occupants. Some of the buildings and sculptures are so beautiful that Lecce is known as “The Florence of the South.” Florence rescued all of Europe from the Dark Ages in the late 14th century as the center of learning, philosophy and science in the Western world, even though much of what they did was just to copy Roman work from 1,000 years before.

Stefania knew all this because her mother was a teacher and taught her history, literature and even Latin. Her father was a train engineer who was terribly proud of his first-born daughter. He watched the way she could absorb knowledge and knew that eventually she would need to leave the small but beautiful city of Lecce and move to one of the big cities of the north.

Stefania, for her part, wanted to grow up to be a housewife like her mother. She didn't always do what her father wanted and, as a teenager, she used to sneak out of the house to go for rides on the back of motorcycles. However, when she was at the top of her class at the Lecce University studying biology, architecture and engineering, her father encouraged her to continue with her studies at a more challenging university. At age 20, Stefania packed her bags and made her way to Polytechnic in Milan.

Milan is much bigger than Lecce. Instead of 100,000 people, Milan has 4 million residents. Stefania had never seen so many people and had to learn new skills just to survive in the city. She had never ridden on a subway nor had to compete against so many other students. She realized that she needed to concentrate on just one subject, and so she relinquished architecture and combined her love of biochemistry with engineering to specialize in chemical engineering.

Even in the big city of Milan, Stefania stood out as a bright and industrious student, and she received an internship at Pirelli, one of Italy's most well known global companies. Although Pirelli is best known for its tires, the company has made all sorts of rubber products since it was founded in 1872. They have made everything from SCUBA equipment to specialized electrical and telecommunication cables. Pirelli manufactured the undersea telecom cable that linked North America to Europe for the first time in the early 1900s.

So it was with the cable division, not the tire division, where Stefania began to apply all that she had learned in university. In the laboratories of Pirelli she studied how the chemical compositions of various additives impacted the performance of the base polymers for coating fiber optic cables – the fiber optic cables that will replace the original Pirelli copper undersea cables that had been laid a decade ago.

Stefania particularly enjoyed learning how to use Pirelli's computer simulation software to model chemical compounds, which quickly showed how the performance of various mixtures would be affected by changing various parameters.

Eventually Stefania decided that she wanted to switch to the tire division. She knew she wanted to work with the motorcycle tires because the researchers working on cables rarely had any interaction with the customers. She had a good reputation for her work at Pirelli but absolutely no experience with tires or tire compounds. Nevertheless, she was selected to work in the motorcycle sport tire division. It was a lucky switch because in 2005 Pirelli sold its cable division to Goldman Sachs, the same douche-bag bankers that would cause the global financial crisis in 2008 and cost tens of millions of people their jobs and unrecoverable economic losses.

It was an honor for Stefania to be selected for the sport tire division because sport street tires are one of the hardest products to develop. Race tires only have to work in a relatively small range of operating conditions, but street tires are going to be over-inflated, under-inflated and have widely different loads. Street tires have to work with a wide range of machines, all of which have different weights and handling characteristics. Plus they have to work in both wet and dry conditions.

Stefania had to learn all sort of new things. She had to learn about material sciences, study carcasses designs and learn how polymer characteristics change with temperature. And, of course, no one ever talks about the "feel" or "feedback" of a fiber optic cable, so there’s no way to quantify such things in her software.

In 2003, a Pirelli test rider would use her first prototype tires at a test track in Sicily. She was so nervous that she couldn't sleep the night before. The tires had been tested extensively on a giant rolling drum so she knew that they would be safe for the rider, but she didn't know how the rider would feel about the three prototypes he would be testing.

Late in the afternoon she got a phone call from her test rider.

Tire One: “Che cazzo!?!?" This was not a very polite review of Stefania's work, and she was very concerned.

Tire Two: “It's okay.” This was better, but Stefania was used to doing exemplary work. If that was the best review she could get, then she had a lot of work ahead of her.

Tire Three: “Perfecto.” And Stefania allowed herself a little smile.

Soon Stefania was promoted to lead a team developing a new tire range for motorcycles. This range would replace the best selling Diablo Rosso (Red Devil) tire.

The Diablo Rosso was a very good tire, and Stefania knew that it would be hard to improve upon it, but she identified two areas for improvement: more grip and longer life. Although usually these two tire characteristics are mutually exclusive, Stefania and her team figured out that the best way to achieve both ends was to put more rubber in contact with the road but have a slightly more durable compound.

Modern tires have two main active ingredients embedded in the underlying rubber or polymer matrix: silica and carbon. Silica is a white powder that is durable and grips well at low temperatures and on wet surfaces, but it lacks the all out grip of carbon. Carbon is black and provides sheer grip on hot, dry surfaces. The trick, as many urban planners have found, is to get the silica and carbon to mix together and deliver results that are better than either compound can deliver on its own. The more carbon added, the better a performance tire will perform on warm sunny track days; the more silica, the better the tire will work on cold rainy commuter rides.

Like other tire designers, Stefania chose a high silica compound for the center of the rear tires, with a band of high traction carbon compound without grooves at the very edges for all-out cornering. To increase the amount of rubber in contact with the asphalt, she and her team further optimized the drainage pattern of the tread to increase the rubber and decrease the voids. This increased the amount of tire on the road at any time by 10% to 20%, depending on where the rider was on the tire profile. Decreasing the sea-to-land ratio of the tire increases both tire life and grip.

But Stefania had not studied chemistry for years just to change a tread pattern. She dug deep into the molecules of silica and carbon and developed new materials and blending techniques to achieve a much more uniform dispersion of the two elements into a new polymer substrate. The better blending allowed for a compound that was more durable and provided better grip in a wider range of operating conditions.

The last trick was to specifically increase the durability and grip of the acceleration zone of the rear tire. This is the section of the rear tire that takes all the abuse when the rider applies power and the bike is still leaned over but not on the sticky edge anymore. The combined tire profile and carcass deflection gives the Rosso II a 17% larger contact patch at half lean than it does straight up or at full lean. By combining the new tread with the new compound, the Rosso II improved upon the Rosso I in dry performance, wet behavior, mileage and wear regularity without adversely impacting stability or comfort.

Stefania had to make the tire work for bikes that were light or heavy, had narrow or ultra-wide (240!) tires, had a skinny or plump rider, and would still work with whatever tire pressure the various bike manufacturers recommended and in all temperatures.

After three cycles of development on the computer, and three cycles of development with real prototype tires, she knew she had a winner when test riders reported that her tires had tamed the recalcitrant nature of the evil-handling FJ1300. Pirelli embraced her work and set about building thousands of the new tires.

In order to sell these tires in America, Pirelli wanted to ingratiate itself with the largest dealer and distributors in the land by inviting them to a party at Miller Motorsports Park. They also invited some professional motorcycle journalists to try the new tires. Best of all, Stefania was invited to attend the event. She was very excited because she had only been to the U.S. once before, and it was a state filled with foreclosed houses and aging New Yorkers called “Flowers.” This time she would be going to Utah, a state filled with natural beauty and a reputation for hospitality, as long as you are not from Arkansas.

Pirelli North America (Pirelli has about 30,000 employees worldwide) had begged, borrowed and rented a wide variety of motorcycles to show how the tires worked on all sorts of bikes. Pirelli had planned to offer a street ride and a track ride, but the street ride was complicated by snow in the mountain passes and conflicting priorities of riding versus taking pictures with pretty backdrops. Eager to learn in any situation, Stefania noticed that the journalists:

     •  Did not seem to care about pretty background pictures;
     •  Wanted to ride as much as possible;
     •  Only seemed interested in the most comfortable bikes for the street ride; and
     •  Only seemed interested in the sport bike at the track.

One journalist, who was also the most handsome, the most articulate, the most erudite and the most insightful, asked Stefania many questions about compounds, chemistry, inflation pressures and operating temperatures. Some of the questions were really hard, but Stefania answered all of them and impressed the writer.

"The aggregate morphology is more homogenous
and the tread has less discontinuity" –Stefania

Later, she saw the writer riding on the track. Not only did he speak the best Italian of the guests (although it was still very poor Italian), he also had the coolest leathers and was leaning the bike over really far in the turns to ride on the sticky carbon compound portion of the tire she had provided for just that purpose!

She found the journalist later and asked him what he thought of the tires she had designed. He described the performance and feel of the tires Stefania knew as compounds and computer models: "I had to keep reminding myself that these are not race track tires but are street tires we are using on the track,” the journalist began. “As I was learning the track, there were some spots where I was using the tire hard but I wasn't leaned over far enough to get into the carbon compound. Riding hard on the silica portion I could get some movement out of the rear, but as I cleaned up my lines I was able to start using more lean angle. Once I started apexing with the carbon compound edge all that vagueness went away.”

Front wear.

Rear wear. A couple hundred miles of street ride,
five hours of track time, and still looking good.

"Miller has a really long straight, and on the RSV4 I could hit a pretty high top speed, even giving up the 15% of horsepower due to the 4,000-foot altitude." (Stefania had to quickly convert his anachronistic measurements into proper metric calculations, but she was a scientist so this was not difficult for her.) "Even at those speeds, and with the gusting crosswinds, the bike was stable and planted. Some of the older Pirellis seemed to feel a little mushy, but these had none of that softness.”

"Being a street tire, they had knee-dragging grip pretty much straight out of the pits. There is a little uphill-downhill-corkscrew section where I was pretty much just putting the bike from one extreme side to the other, and I never felt the front step, slide or push. This wasn't at full-tilt race pace, but it was at a pace that matched, say, the fastest track day rider."

"They let me double stint one of the riding sessions, so I stayed out for 40 minutes straight to see if I could overheat the rear or start getting some tread distortion. Granted, I was on an R6 that was pretty much gutted from the altitude, but even after hours of track time and my 40 minutes of straight abuse the tires looked and felt great."

"Tires feel good on the edge." –Sam

"Maybe they would overheat and get greasy in 100-degree sunny temperatures with full-powered liter bikes?" Stefania knew that the tires had been tested in the very hot climate of Sicily and, therefore, would not "overheat and get greasy," but she didn't feel the need to point that out to this American.

"Stefania" he said, butchering the pronunciation of her name, "Pirelli hired the Yamaha Champion School guys to lead around the dealers and distributors. Dale Kieffer is a great guy and a friend of mine. Would you like me to ask him if he can get you out on the track so you can see how good your tires are for yourself?"

This was very unexpected for Stefania. She had ridden on the back of motorcycles for 24 years but not for a while and only twice on a racetrack. Dale was very nice and got her dressed up in school leathers and a helmet and introduced her to Ken Hill for the ride. Ken took her for four laps around the racetrack on the back of a Yamaha FZ1.

She took to the track at 8:00 p.m. It was still light, but the late hour meant the snow-capped mountains were glowing gold. It was like nothing she had ever seen before. Ken took the first lap a little slow to let her get used to the bike, but he could tell she was comfortable and so he went really fast for the next three laps.

She knew that she had designed the tire for two-up riding, for all sorts of bikes, and for all sorts of conditions, but she was not expecting the speed Ken used to pilot the motorcycle through the turns. He was going 250 k.p.h. and could slow down very quickly and even turn when he was still braking. She could hear the footrest grinding on the ground, and the asphalt looked so close she felt she could touch it. She knew she should be scared, or at least nervous, but it was exhilarating to do something so exciting knowing that her design was the key to the entire experience!

She felt connected to the bike, the track and the line around the circuit. And on the fourth lap, when Ken put the bike on its side at 140 k.p.h., she forgot about chemistry and finally understood "feel.”