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On a regular basis, we all encounter breakneck moments when we’re pushing our bikes and ourselves to the limit. Then, a sudden twist in the road, an off-camber turn or an oil slick could leave us in a pool of blood at the roadside. Usually, we trust our gut reactions and time-acquired skills to deal with such situations, but they can still leave us feeling shaky or shattered.
Words and Images by Steve Thomas
No matter how good a bike handler you are, or how expensive your bike, the fact is that the only thing separating you from disaster in these situations is that skinny 20-plus millimeters of rubber that holds you to the road. Yes, your tires are what determine the outcome of every ride. But, strangely enough, we often pay scant regard to them. Perhaps we’ll ride cheaper- grade tires to save winter bucks or push paper-thin treads to the threads, holding on to a bulge—which is absolutely crazy when you consider just how crucial those tires and the right choice of rubber are to your ride…and your life.
Recently, multiple research outlets have come to the conclusion that wider tires are actually faster, which is slowly turning on many a seasoned rider to the delights of the “over an inch” club. So we don’t have to sacrifice comfort, safety and durability for a faster and easier ride. Wider tires can boost all of these factors and, who knows, maybe the bike industry will eventually realize that a little more clearance needs to be factored into frames.
Tire design and production is a lengthy process. Treads, compounds and sizes are planned anywhere between one and three years ahead of completion. Market demand and production trends are key in determining what’s manufactured, although there is always room for innovation and new technology.
Kenda and other tire companies can make just about any type of product, whether it’s an ultra-durable tire, a super-grippy wet-weather tire or an ultra-fast-rolling strip of rubber. However, it’s budget and demand that determine what we eventually use. There are not many of us who would buy a tire that rolls super-fast but lasts for just one long race, or something purely for slippery and wet roads. So it’s a game of compromise, with the aim of making the best possible tire for all-around use at a certain price point.
Many bike (and car) tires come from a select number of factories and are then re-branded. The differences in quality can be hard to decipher, and if all brands are similarly placed their success might depend on savvy marketing—which is not Kenda’s primary strength.
FROM TREE TO TREAD
The whole process starts just after dawn in remote areas of Thailand where rubber trees are tapped by hand to slowly extract the raw latex. The latex is dried and chemicals are added before it’s shipped in block form to the Kenda factories in Taiwan and around Asia. The initial “black magic” comes from the chemicals added when the rubber reaches the factory. These vary a little, depending on the desired compounds for the final product, which in turn determines the characteristics.
The prime additives are sulfur, carbon black, antioxidants and zinc oxide, which are mixed with the natural latex and synthetic rubber during the initial blending and mixing stage. Carbon black is what gives the majority of tires their coloring, and consequently their durability. For colored tires, a white carbon additive is used, but it does lessen their longevity. The make-up of this blended rubber is what gives a tire its basic properties. For fast-rolling race tires such as the Kenda RC3 a single soft compound is used to lessen rolling resistance, while for longevity the LR3 has a harder “pro” compound. Dual compounds are also used to strike a balance between these direct characteristics—harder compound in the center of the tread, and softer side compounds, as used in the RC2 tires.
When it comes to the choice of wired or folding tires, it’s mostly a weight issue. Folders are lighter and also have a higher tensile strength due to the Aramid fiber used in the foldable beading—which also costs more and takes longer to produce.
Threads per inch (TPI) is something we all hear about but probably don’t really know what it means to a tire and its characteristics. Basically, the lower the TPI the wider the denier of the tire casing, meaning that more rubber is used, which makes the tire more durable—and heavier. Higher TPIs give a faster and smoother ride, and make for a lighter tire because less rubber is used. The TPI is determined by the denier of the casing, to which the rubber is applied. At this stage, Kevlar sheeting can also be used to increase the casing’s puncture resistance.
Another rubbery word, vulcanization (nothing to do with “Star Trek”!), is a process in which a tire is put into a mold, has a tube placed inside and is then heated to 175 degrees Celsius. It becomes partly liquidized and has its tread formed by the mold—it’s fascinating to watch. The tread patterns determine the tire’s ultimate ride sensation and grip, with deeper tread patterns offering more side-water dispersion and being favored for wet grip. When they finally resemble the tires we know, they all go through a curing process to seal and treat the finished article, ready for the open road. Well, almost.
Kenda has been making tires for just over half a century, and it all started in the factory I visited in Taiwan. Still the headquarters of this family-run business, it’s a huge and surprising place. Naturally enough, it’s hot and odorous; such is the nature of rubber. But what really hits home is the factory’s hands-on element—from start to finish.
Small farmers work in the Thai rubber plantations to supply latex to commercial giants such as Kenda—where you would imagine that robots and the likes take over. But, no. There’s a whole lot of machinery involved in the numerous processes of making tires, but each one of these machines is hand operated, checked and observed. On an average day of production some 20,000 bike tires and 70,000 inner tubes emerge from this single factory. As a group, the total daily tally runs to 258,000 bike tires and 395,000 inner tunes— both Kenda and other familiar brands.
That’s a whole lot of rubber and, what’s more, every single tire and tube is hand checked. Every inner tube is inflated, checked and then left pumped up for 24 hours. This heavy hands-on element is apparently commonplace within the tire business—meaning that every single tube you trash and every tire you procrastinate over buying is actually hand made. It gives a whole new appreciation for those black strips of rubber that help to hold you and your bike to the road.