In the labyrinth of tunnels

Henri Lesewitz

 · 04.03.2017

In the labyrinth of tunnelsPhoto: Henri Lesewitz
In the labyrinth of tunnels
Germany's only production facility for bicycle tyres is located in the middle of the Hessian province. Reporter Henri Lesewitz was allowed to take an exclusive look inside the "hallowed halls" of Continental.

Science creates knowledge - and some of it is astonishing. The largest tyre manufacturer in the world is not Goodyear or Michelin, but Lego. The assembly lines of the Swedish building block manufacturer churn out 675 million tyres for toy cars every year. With such quantities Continental cannot come up with. But the company has another superlative to offer. It is the only producer of bicycle tyres in Germany. The factory in Korbach, Hesse, has been in operation since 1907. In order to withstand the brutal cost pressure in the original equipment manufacturer market, a factory was opened in Asia a few years ago. However, around 50 employees in Korbach continue to manufacture the high-quality product lines - almost 50 per cent of the Conti range - by hand.

Anyone passing through the barrier at the company entrance is first of all amazed by the extensive labyrinth of hall complexes that has grown over the course of more than 100 years from the legendary "Conti chimney" to the green hills that surround the small town of Korbach. More than 3000 people work here, most of them in car tyre production. The bicycle department, which is located in the older, front part of the company, is tiny compared to the rest of the site. BIKE reporter Henri Lesewitz was allowed an exclusive look inside the "hallowed halls", as Conti employees call the bicycle tyre area with a mixture of pride and respect. Product Manager Sebastian Moos was discreetly guiding our reporter past the mythical rubber compound kitchen "Building 18" ("Secret!") when he spontaneously suggested: "Hey, want to build a tyre?" What do you mean? A real mountain bike tyre? Build it yourself? Here in the hallowed halls of Korbach? Of course!

Competition: We raffled off the hand-built set of Conti tyres by Henri Lesewitz (until 28.03.2017)!


You can read the complete Continental report - the second part of our Made in Germany series - in BIKE 4/2017 - on newsstands from 7 March. You can also read the complete issue in the BIKE app (iTunes and Google Play) or in the DK shop order:

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How an MTB tyre is made at Continental

  Other towns have a castle in their coat of arms, or an eagle. Korbach's emblem is said to be the old Conti chimney. The antique furnace is part of the old boiler house, where the heat for the vulcanising presses was produced for decades. The yellow "chimney belly" is a water tank. Today, Continental operates a waste incineration plant together with the city of Korbach. In order to utilise the heat as effectively as possible, work is carried out in a three-shift system.Photo: Henri Lesewitz Other towns have a castle in their coat of arms, or an eagle. Korbach's emblem is said to be the old Conti chimney. The antique furnace is part of the old boiler house, where the heat for the vulcanising presses was produced for decades. The yellow "chimney belly" is a water tank. Today, Continental operates a waste incineration plant together with the city of Korbach. In order to utilise the heat as effectively as possible, work is carried out in a three-shift system.  Sebastian Moos is one of three product managers in Continental's bicycle division. He is responsible for the mountain bike models. It takes just under a year to develop a new tread. The great art is to find the optimum compromise between grip, rolling properties and mileage. Every type of MTB has its own special requirements. The structure of a tyre is roughly the same for every model: at the bottom is a rubber mat interspersed with ultra-thin, stable nylon threads - the carcass. On top of this is the significantly thicker tread. And the aramid threads on the sides to ensure that the tyre sits firmly on the rim.Photo: Henri Lesewitz Sebastian Moos is one of three product managers in Continental's bicycle division. He is responsible for the mountain bike models. It takes just under a year to develop a new tread. The great art is to find the optimum compromise between grip, rolling properties and mileage. Every type of MTB has its own special requirements. The structure of a tyre is roughly the same for every model: at the bottom is a rubber mat interspersed with ultra-thin, stable nylon threads - the carcass. On top of this is the significantly thicker tread. And the aramid threads on the sides to ensure that the tyre sits firmly on the rim.  Ever since the long-bearded Ulf from the vulcanising department modelled for one of the company's advertising campaigns, he has enjoyed cult status among employees. He now works in quality assurance. Everyone knows him. Motifs from the former "Made in Germany" campaign can be found everywhere.Photo: Henri Lesewitz Ever since the long-bearded Ulf from the vulcanising department modelled for one of the company's advertising campaigns, he has enjoyed cult status among employees. He now works in quality assurance. Everyone knows him. Motifs from the former "Made in Germany" campaign can be found everywhere.  Before we set off, we first make a detour to the shoe department. Work shoes are a must. Which is why they are available in all sizes.Photo: Henri Lesewitz Before we set off, we first make a detour to the shoe department. Work shoes are a must. Which is why they are available in all sizes.
  Like carpeting in a carpet wholesaler, the raw rubber mats are stored on the heavy-duty shelves of the so-called calender hall. It is station number two after the unfortunately secret building 18. If you are ever confronted with the question (quiz!) of what tyre rubber is made of, then watch out! It's rubber, carbon black, sulphur, oils and a few other little things. "Conti tyres are vegan, by the way," informs Product Manager Moos. And yes, some customers would actually ask about this. Also a nice bit of trivia knowledge.Photo: Henri Lesewitz Like carpeting in a carpet wholesaler, the raw rubber mats are stored on the heavy-duty shelves of the so-called calender hall. It is station number two after the unfortunately secret building 18. If you are ever confronted with the question (quiz!) of what tyre rubber is made of, then watch out! It's rubber, carbon black, sulphur, oils and a few other little things. "Conti tyres are vegan, by the way," informs Product Manager Moos. And yes, some customers would actually ask about this. Also a nice bit of trivia knowledge.  The calendering machine, which is the size of a detached house, cuts the rubber to the perfect thickness and weaves in the nylon threads at the same time, making the carcasses three times as strong as Coke cans, but leaving them as flexible as possible. It's hot. And loud. A huge spectacle.Photo: Henri Lesewitz The calendering machine, which is the size of a detached house, cuts the rubber to the perfect thickness and weaves in the nylon threads at the same time, making the carcasses three times as strong as Coke cans, but leaving them as flexible as possible. It's hot. And loud. A huge spectacle.  Several employees monitor the work process with eagle eyes. The quality must be 1a. The "Made in Germany" seal of quality is an obligation. Reporter Lesewitz has to be patient. There's nothing for him to do here yet.Photo: Henri Lesewitz Several employees monitor the work process with eagle eyes. The quality must be 1a. The "Made in Germany" seal of quality is an obligation. Reporter Lesewitz has to be patient. There's nothing for him to do here yet.  Yummy, yummy! The company canteen's lunch menu is broadcast on a flat screen in the production hall, bilingually in German and English. Turkey breast with rice noodles, neck steak, fish or something vegetarian? This increases the workers' anticipation of their well-earned break.Photo: Henri Lesewitz Yummy, yummy! The company canteen's lunch menu is broadcast on a flat screen in the production hall, bilingually in German and English. Turkey breast with rice noodles, neck steak, fish or something vegetarian? This increases the workers' anticipation of their well-earned break.  The tyre material is ready. So roll it up meticulously into bales, label it and take it up to the cutting room on the floor above.Photo: Henri Lesewitz The tyre material is ready. So roll it up meticulously into bales, label it and take it up to the cutting room on the floor above.  Spools, conveyor belts, winding machines: The metre-wide rubber sheets from the calender machine are portioned to the required widths and rolled up again.Photo: Henri Lesewitz Spools, conveyor belts, winding machines: The metre-wide rubber sheets from the calender machine are portioned to the required widths and rolled up again.
  At last! Mission for colleague Lesewitz. The tyres are glued together on a complicated-looking machine. One turn of the roller and the carcass is ready. Another turn and the tread is on. Now the labels and the aramid threads on the sides. The raw tyre is finished. Well, a few intermediate steps are still necessary. Tyre builder Steffen Krüger patiently lends Lesewitz a hand and reveals a few secret tricks in the slang of his native Brandenburg. For example, the trick of how to properly tear the rubber from the roll. "Here, put your foot on the switch - then just pull the end off in one go and pull it straight off."Photo: Henri Lesewitz At last! Mission for colleague Lesewitz. The tyres are glued together on a complicated-looking machine. One turn of the roller and the carcass is ready. Another turn and the tread is on. Now the labels and the aramid threads on the sides. The raw tyre is finished. Well, a few intermediate steps are still necessary. Tyre builder Steffen Krüger patiently lends Lesewitz a hand and reveals a few secret tricks in the slang of his native Brandenburg. For example, the trick of how to properly tear the rubber from the roll. "Here, put your foot on the switch - then just pull the end off in one go and pull it straight off."  If you look over Steffen Krüger's shoulder for a while, you will be fascinated by the speed and precision of the work. Fine red laser beams (shown in the picture to the right of the tread) mark where the tyre needs to be fitted with tenths of a millimetre precision. When the tyre blank is ready, Krüger checks everything with the measuring tape. Phew! The Trail King 27.5 x 2.2 tyre from reporter Lesewitz passes the quality control.Photo: Henri Lesewitz If you look over Steffen Krüger's shoulder for a while, you will be fascinated by the speed and precision of the work. Fine red laser beams (shown in the picture to the right of the tread) mark where the tyre needs to be fitted with tenths of a millimetre precision. When the tyre blank is ready, Krüger checks everything with the measuring tape. Phew! The Trail King 27.5 x 2.2 tyre from reporter Lesewitz passes the quality control.  Reporter Lesewitz with his work! Incidentally, every Conti tyre has a number on it that makes it clear who made the tyre. In Lesewitz's case, it's 666, which somehow just popped into his head. Probably because he was listening to the legendary 1982 Iron Maiden album on the train journey to Korbach: "666! The Number of the Beast!" Connoisseurs of the heavy metal music genre know all about it!   Photo: Henri Lesewitz Reporter Lesewitz with his work! Incidentally, every Conti tyre has a number on it that makes it clear who made the tyre. In Lesewitz's case, it's 666, which somehow just popped into his head. Probably because he was listening to the legendary 1982 Iron Maiden album on the train journey to Korbach: "666! The Number of the Beast!" Connoisseurs of the heavy metal music genre know all about it!   "Hah!", we now hear it screeching from the ranks of impatient readers! "There's still no profile on it! Where are the studs now, hmm?" Just a tiny moment of patience! After gluing, the tyres are still as bald as newborn babies. But they're about to start studding!Photo: Henri Lesewitz "Hah!", we now hear it screeching from the ranks of impatient readers! "There's still no profile on it! Where are the studs now, hmm?" Just a tiny moment of patience! After gluing, the tyres are still as bald as newborn babies. But they're about to start studding!  Alexander Abdo meticulously scans every square millimetre for any damage or defects. Only absolutely perfect tyres are allowed onto the transport racks, which are rolled towards the packing department every twenty or thirty minutes.Photo: Henri Lesewitz Alexander Abdo meticulously scans every square millimetre for any damage or defects. Only absolutely perfect tyres are allowed onto the transport racks, which are rolled towards the packing department every twenty or thirty minutes.  Hossa! It's as hot here as in a climate zone near the equator! Vulcanisation is the name of the steaming, hissing department in which the blanks are baked into ready-to-run tyres. 172 degrees, 15 bar pressure, 280 seconds. Blank in, press button, wait, take tyre out, done. Conti specialist Alexander Abdo shows how it works. There are around 60 of these heating presses in total.Photo: Henri Lesewitz Hossa! It's as hot here as in a climate zone near the equator! Vulcanisation is the name of the steaming, hissing department in which the blanks are baked into ready-to-run tyres. 172 degrees, 15 bar pressure, 280 seconds. Blank in, press button, wait, take tyre out, done. Conti specialist Alexander Abdo shows how it works. There are around 60 of these heating presses in total.
  Okay, one more time. It steams, it hisses: just watching it is pure joy.Photo: Henri Lesewitz Okay, one more time. It steams, it hisses: just watching it is pure joy.  A load of freshly baked "Race King". Now it's time for the packaging, then it's off to the shops.Photo: Henri Lesewitz A load of freshly baked "Race King". Now it's time for the packaging, then it's off to the shops.  The tyres are packed by hand. It takes some practice to do this perfectly and quickly. Reporter Lesewitz despaired when trying to get the folding right.Photo: Henri Lesewitz The tyres are packed by hand. It takes some practice to do this perfectly and quickly. Reporter Lesewitz despaired when trying to get the folding right.  Made it! A set of "Trail King 27.5 x 2.2" tyres, built by BIKE reporter Henri Lesewitz.Photo: Henri Lesewitz Made it! A set of "Trail King 27.5 x 2.2" tyres, built by BIKE reporter Henri Lesewitz.

The winner: The hand-built set of Conti tyres from Henri Lesewitz goes to Andreas L. from Riegsee - congratulations!

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