Rennie Scaysbrook | August 7, 2023
Thirty years ago, Metzeler revolutionized the tire game when it bought out the 0° steel belted radial. Tires have never been the same since.
Yet another set of Metzelers rolls off the production line in the factory just outside of Frankfurt in Germany.
As a young lad, my dad would play golf each Sunday with his close friends at a course at the end of our street. The summer months were always better for me because it was then a special mate of dad’s would come and play after the 500cc Grand Prix season had finished.
The late Warren Willing, one of Australia’s finest ever racers and one of the driving forces behind Kenny Roberts’ feared Marlboro Yamaha team of the early 1990s, was a plethora of information. As an annoying pre-teen, I’d drill him at any given opportunity about GP bikes, about racing, about what Wayne Rainey was doing in the off-season, anything I could think of.
A man of few words, Warren would occasionally say something that would really hit home. Two of those quips have stuck with me in every form of my riding since, be it racing, street, motocross, adventure, whatever.
The first and coolest line was, “A motorcycle is not like a car. It’s much closer to a fighter jet in the way in moves and reacts to the rider’s physical input.”
Pirelli/Metzeler’s Executive Vice President of Research and Development and Cyber, Pierangelo Misani (left) with Pirelli/Metzeler’s Head of Global Testing and Technical Relation, Salvatore Pennisi—two men that are largely responsible for Metzeler’s ascent over the last 30 years.
And the second was, “Tires are the single most important thing on your motorcycle. Tires are the thing that allow your engine to deliver the power, for the chassis to work as it should, and for your brakes to slow you down.”
I’ve carried that quote with me wherever I’ve gone in this motorcycling life, so when Metzeler, a company I’ve worked closely with over the years, asked me to come to their factory in Hesse, located about an hour’s drive northeast of Frankfurt to commemorate a very special anniversary, the answer was obvious.
You Gotta Have Steel
2023 marks 30 years since Metzeler debuted zero-degree steel belt technology in motorcycle tires. And while it hasn’t been plain sailing, the introduction of the first commercially available zero-degree steel belted tire in 1993 signaled the beginning of the next generation in tire advancement and the end of cross-ply radial tires.
I think it’s fair to say we take tires very much for granted these days. Tires are now so good across the board from all the manufacturers, be they Dunlop, Michelin, Pirelli or Metzeler, but this wasn’t always the case.
Legendary German rider Helmut Dähne on his way to breaking the Nürburgring Nordschleife lap record in 1991 on pre-production 0° belt Metzeler radials.
The 1980s heralded the start of the horsepower race from Japan. The Suzuki GSX-R750 arrived on the scene, a few years later it was Yamaha with the FZR750R (OW01), and as the engines got faster with each passing year, the chassis needed to be stiffer to harness the extra performance and thus tire technology was being left behind.
“After the 1970s in Europe, motorcycling really took off and there was a huge development of the big displacement bikes,” says Pirelli/Metzeler’s Executive Vice President of Research and Development and Cyber, Pierangelo Misani. “The speed was starting to be more important. The world of motorcycling in terms of tires had always been based in the past on cross-ply construction. However, the automotive segment had already switched to steel radials some 20 years prior, but the motorcycle world had not yet adapted.”
This was an optimistic time at Pirelli, which had earlier in 1979 completed the purchase of Metzeler and bought everything in house. The first innovation came in the form of the Metzeler Belted System (MBS), developed for the diagonal Kevlar belt on cross-ply tires of the 1980s, but it was only the beginning.
The processes in constructing tires are becoming ever more mechanized, resulting in a degree of accuracy not possible with just humans alone.
A tire is nothing but a spring, or, rather, a spring and a damper.
“The spring is made by the construction, by the carcass. The damper is all the rubber that is inside,” says Misani. “Bikes are inherently unstable. The only way to make them stable is the tire, but the tire also creates a character to the bike. As a tire wears down, many assume it just loses grip. That is true to some extent, but what really happens is the wearing down of rubber means you lose the damping effect the tire was designed to give. Less rubber, less damping of the forces.”
Where steel showed its real benefit was in compression resistance—again, learned from the automotive side that required high sidewall strength to avoid deformation. For a bike, it allowed the tread to stay uniformly connected to the road while the motorcycle was leaned over without caving in on itself and you crashing to the ground.
Over time, Kevlar tire belts had moved from 90° to the direction of travel, to alternating 35-40° patterns with the MBS. Now, the option of a 0° belt became a possibility, but using steel.
“Our French competitors [Michelin] were the first to explore this construction,” admits Misani. “They could go in the direction of having a good tire that lasted a long time on the motorway, but not a good tire when you go to a racetrack. It was either one or the other.”
Metzeler could see the possible benefit of the usage of steel and thus pushed the development further.
Metzeler radials have been standard fitment with compatriots BMW for many years.
“When you are leaning into the corner, the tire has a strong pull from the carcass, so the intrinsic stability of steel versus textile or cable could help. And it did help,” Misani says. “What we found is a zero-degree construction reacts with half the force of its predecessor. That means you have half the disturbance, so the tire is lighter and is more stable.
“We called the tire Dr. Jekyll and Mr. Hyde. It would work well when you rode calmly on the motorway, even when worn out, but it would still perform well when reaching lean angles of 45° or more.”
Granted, this is the early 1990s and long before the 60°-plus you can get from today’s street tires.
It was left to Pirelli/Metzeler’s Head of Global Testing and Technical Relation Salvatore Pennisi to conduct the first on-road tests.
“We had a GSX-R750,” Salvo said. “I tested this bike on a motorway in a very fast condition, and with our radial tire the handling, in terms of sporty use and so on, was excellent. But in the motorway, it was a little bit nervous, we could say. With the first prototype of zero-degrees steel belt, the speed you could hold was incredible. Full speed! There was just one problem—this tire was not possible to lean [into the corner]. It was not stable, so we had to completely redesign the tire.”
The instability of the first 0° steel belted radial tire meant a complete rethink on how street tires were conceived and constructed. The old way of thinking was tires needed to be almost triangular shaped, with small radii in the middle. The steel belted construction flipped that thinking on its head, with the first production MEZ1 a much rounder shape with a slightly higher radius in the center than in the shoulder. The compounds also came in for a redesign.
The year 2000 saw the release of the world’s largest motorcycle tire—the 240/40R18 rear tire.
“We went much harder than before,” says Masani. “The compounds to make a zero-degree work had to be harder—not less grippy—because grip is a different story. You have stiffness, and you have hardness.
“The hardness is the capability of the tire to envelop the road surface. The stiffness is the characteristic of the construction. We had to develop tires that are stiffer but not so hard to compromise the grip, of course. This was the challenge.”
Testing was carried out on German autobahns and the Nürburgring Nordschleife using an army of Metzeler hired guns, including then WorldSBK rider and now Ducati MotoGP General Manager Davide Tardozzi, WorldSBK, MotoGP and EWC racer Adrien Morillas, four-time World 250 and 350 Champion Walter Villa, and legendary German racer Helmut Dahne.
Villa’s comments on the new tire were not so welcome, the German telling Salvo and his crew, “After five laps, I was running on steel. There’s lots of sparks. Great for the spectators, not so much for grip.”
After redesigning the 0° steel belted radial tire yet again, Metzeler finally got it right. The first MEZ1 of 1993 saw Dahne break the Nordschleife lap record with a Honda RC30, and Yamaha gave Metzeler the nod to have the MEZ1 as original equipment on the rear of their FZR600.
A year later at the Nardo proving grounds in Italy, Salvo, Suzuki Germany, German magazine Motorrad and a selection of Metzeler riders broke six world records in 24 hours by riding a MEZ1-shod Suzuki RF 900 R 5900.426 km (3666.354 miles) with an average speed of 152.764 km/h (94.448 mph).
Salvo (center, with white helmet) and the Suzuki Germany/Motorrad Magazine team after they broke six world records in 24 hours in 1993.
Some 10 years after Freddie Spencer won the first 500cc Grand Prix using a radial ply tire, Metzeler had delivered and proven the first steel-belted radial tire and delivered it to the public.
Fast forward four years to 1998 and when Suzuki released their great flop, the TL1000R, it came to market with the first front 0° steel-belted radial tire—the MEZ3. Front and rear 0° steel belted radials were now a thing for the buying public.
Over the years, the technology has steadily progressed. In 2002, Metzeler patented the Metzeler Advanced Winding (MAW) technology, a system that optimized the spacing between the steel belts that allowed the engineers to manufacture in certain handling characteristics.
Another six years passed before Metzeler started altering not just the spacing between the chords—each made up of 12 strands of twisted steel—but also the tension of the chords themselves. The process allows for different stiffness levels to be created in different areas of the tire.
The next realms of 0° concept is slated for 2024, one that is likely to focus on ultimate racetrack performance, which we’ll no doubt be front and center to test when it becomes available.
Thirty years on, the inception of the 0° steel belted radial tire remains one of the true milestones in tire production, making riding faster, more enjoyable, but most of all, safer. CN
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Thirty years ago, Metzeler revolutionized the tire game when it bought out the 0° steel belted radial. Tires have never been the same since
