Bicycle tire

The bicycle tires has significant influence on light running, driving comfort and traction of a bicycle. It is usually made of the tire, also called jacket or blanket, and the hose. The mantle is the outer, tough part of the bicycle tire, it holds the tire against the internal pressure stable and transmits acceleration, braking and cornering forces on the ground. In general, it is provided with a profile. The inner tube is provided with an airtight valve, he keeps the tire pressure. In racing tubulars are used in which the sheath encloses completely the hose.

• 4.1 Size information
• 4.2 ratio of tire to rim width

History

Pneumatic tires were invented almost simultaneously by the Scottish veterinarian John Boyd Dunlop ( 1888) and the Frenchman Édouard Michelin (1889 ). Initial developments were two-wheeler tires which were soon developed for pneumatic tires of automobiles.

Until about 1995 there was in Central Europe clincher: The beads of the tire and its rim were about three times wider than with clinchers, and the beads of the tire ( which did not contain wire ) were hooked behind the beads of the rim in full length.

Types

All tires have a carcass of fibers, which limits the extensibility of the tire and keeps the mold. The density of the carcass is with the unit EPI or TPI - specify (Ends / threads per inch " threads per inch ").

Clincher

Wire tires are by far the most commonly used. At the lower end of the two tire flanks, a solid core or thin strands of existing metal wire is incorporated in each case forming a bead of the surrounding material. The rim has sections, which receives the two beads ( right and left), thus keeping the tire securely. The rim is called deep bed, wire tire or rim hook.

Tubular

In the tubular casing is sewn around the tube. He is stuck with Rim or rim tape. The advantage of this design is the low weight and usually a very low rolling resistance. Repairs are costly and tedious, which is why tubular tires are usually replaced in case of breakdown. The correspondingly high costs mean that tubular tires are mostly used in professional sports. In track cycling tubulars are prescribed clincher can not accommodate the required high pressures above 10 bar.

A disadvantage of tubular tires is that the tire glue can heat up so much on long downhill that it becomes soft and the tire from the rim slips ( for example, in the accident of Joseba Beloki in the Tour de France 2003 ). Lightweight carbon wheels are only suitable for tubular tires.

In cyclocross tubular tires are used almost exclusively. This mild to moderate profiled tires typically have a width of 28 to a maximum of 35 mm. As is operated at cross-country race with very low tire pressure - depending on the road surface and weather from 1.8 to 3 bar - come here the clincher significantly behind: You have through the rim at the same width a lower overall height, so that it is more common to breakdowns comes. That compared with Tubular rims relatively sharp-edged rim is slightly damaged on the one hand, it also leads to a faster damage to the tire and thus to a plate. To avoid this, the driver would have to operate with higher air pressure, which in turn will cost traction and comfort.

Even when Radball tubular tires are used. These are to better grip to have almost no profile on the floors of gyms.

Solid rubber tires

Solid rubber tires are mounted on the same rims that are made for clinchers. The advantage of solid rubber tires is the high puncture resistance, which is paid for with high rolling resistance and extremely high weight. The installation of solid rubber tires is often difficult. Solid rubber tires were the forerunners of today's pneumatic tires, they were 1880-1890 in use. Again and again, the idea of ​​solid rubber tires came on, she sits down, however, because of the overwhelming disadvantages not.

The material mixture

The rubber compound of the tire is manufactured, is to unite different, sometimes competing properties: low rolling resistance, high adhesion, low abrasion, durability, sturdy lugs.

Special attention always is on the trade-off between low rolling resistance and good wet grip. Good adhesion means that the tire is to absorb a lot of energy, while the rubber mixture is to use as little energy for low rolling resistance. A good compromise is achieved for example by the silica filler. Another possibility is to use multiple rubber compounds in a tire ( dual and triple compound technology). Especially for everyday bikes that are used all year round, there are special winter tires. These tires are rubber compounds are used that are designed to operate at low temperatures and the best possible adhesion in wintry road conditions. Partial spikes are incorporated into these tires.

Previously, the tire was inside ( a finely ground, natural, hydrated magnesium silicate) sprinkled with talc to prevent sticking of the tire and tube. Today, the hoses are factory-fitted with a thin layer of talc. After patching a tube you should renew the talc layer around the mend.

Tire and rim sizes

Size information

In Europe, three terms are used:

• Specifying, in inches for example, 28 × 1.75 ", the first number indicates the approximate outer diameter and the second is the approximate width. Customs data are particularly common for mountain bikes. From the measurement in inches of the tire can not be closed on the rim diameter. There are, for example, " 26 inch " and four in " 20 inches " even six different rim sizes ( see table). There are also inconsistencies, for example, need 28-inch tire rims smaller than 27 -inch tires. There are also some tire sizes, the conclusive fit into none of the patterns and cause conflicting size information, as some French tire.

• The French term, which consists of a three digit number, often behind with a letter. The number designates the approximate outer diameter of the tire. Similar sizes are marked with the same number but different letters, so 650C corresponds to a rim diameter of 571 mm and 650A tires for 590 mm rim diameter.

• The metric designation in millimeters according to the European ETRTO, for example 47-622, where the first number indicates the approximate ( generously estimated ) indicates width of the tire and the second the exact nominal diameter of the rim. Although the ETRTO specifications are always unique and avoid misunderstandings, they sat down by slowly. They are mainly common in racing bikes. The ETRTO has defined only tire sizes with a certain degree of dissemination; for many rare tire sizes there is no ETRTO information.

• Partial is a mixed term (diameter in mm and width in inches) to be found.

A detailed table with the mappings between the two descriptions is the section links.

Ratio of tire to rim width

There are both tires and rims in different widths. There are for each rim width is no single appropriate tire width, but always a certain range. As a rule of thumb it can be said that the tires do not narrower than the opening width of the rim and should be as wide at most twice. Tires that are narrower than the rim, prone to breakdowns ( high air pressure reduces the risk). At wide tires burden the rims over charge ( lower air pressure reduces the risk ) and, in extreme cases, the coat slip off the rim.

The recommended by the ETRTO standard values ​​can be seen in the table in this section.

Air pressure

The allowable internal pressure is usually indicated in the tire sidewalls in at least two different units, for example, in bar, psi or kPa. In principle, need narrower tires have a higher inflation pressure.

Aspects of the selection of the tire pressure:

• Low pressure means greater rolling resistance on paved roads. When lowering the tire pressure increases the flexing of the tire and thus its rolling resistance. This also reduces the life of the tire, because the side surfaces of the tire be faster brittle. On uneven ground with soft ground, however, decreases the rolling resistance as the tire may be less deeply sink into the ground and bumps are better rolled over.
• Low pressure means off paved roads better traction or power transmission.
• Low pressure reduces the stability in inclined positions thereby deteriorating the performance of the wheel. In curves, the so-called occurs " swimming", i.e. the wheel moves transversely to the direction of travel.
• Depending on the air pressure and the tire thickness of several millimeters of travel may be generated. The higher the pressure, the suspension or less comfort. Bumps are then transmitted directly to the frame.
• Low pressure may result in the wandering of the tire in the longitudinal direction on the rim. Here, when the tube is adhered to the tire, there is the danger of a demolition valve.
• Too little pressure in the risk of a flat tire.
• The correct air pressure also depends on body weight. At higher weight of the air pressure is higher to choose.
• The air pressure depends also ( very slightly ) from the ambient temperature (see also Thermal equation of state of ideal gases, gas laws ). When the temperature drops, you follow the pressure equivalent level down.
• The stress on the rim sidewalls depends on the air pressure and the tire width. The reason is that the force is proportional to the product of tire pressure and tire width of the flanks of the wheel rim and thus at the same tire pressure exerted by wider tires, a higher force on the rim. In some lightweight wheels the manufacturer shall specify the maximum allowable air pressure depending on the tire width. The wider the tire, the lower is the maximum allowable pressure.

The optimum air pressure depends on the above-mentioned aspects, but also on personal taste:

• When mountain bike traction and suspension are in the foreground. The pressure in the terrain moves 2-4 bar, with tubeless 1.8 to 2.5 bar. So little pressure, however, is mobile with tires that are designed for commercial tires are likely to crack in the edge
• When touring bike and trekking bike you put more emphasis on low rolling resistance and puncture resistance, the pressures are 3.5 to 6 bar here.
• Racing bikes, whether by wire or tubular tires, bar be driven on the road with about 7 to 9. When wheel 10 to 13 bar, with record-breaking runs it too. From a pressure of about 14 bar, the tire is considered " totgepumpt ," meaning he loses essential properties of the cushioning and force redirection in collisions, so that the ride comfort decreases.

Puncture resistance

In principle, the puncture resistance of the rubber mixture, the tire thickness, the density and nature of the threads in the fabric is dependent on the base and on the air pressure.

There are tires with a completely vulcanised in the area of the tread band from aramids or comparable materials. This is to prevent the penetration of glass, thorns and other foreign bodies. However, this puncture protection works only for foreign matter entering through the tread, the tire walls do not have strong protection. The disadvantages of this puncture protection are higher weight, higher rolling resistance and reduced ride comfort. Due to the stiffness of the puncture protection such tires are often a bit more difficult to assemble.

Bicycle shops also puncture protection tapes are offered, which are placed between the tire and tube and, unlike the built-in puncture protection belt after a tire change ( for example, due to wear) can still be used. Rolling resistance and ride comfort change in this solution does not, however, the assembly of these stubborn tapes is very time consuming and requires expertise.

Durability

The mileage and tire life varies greatly with the rubber mixture, thickness of the rubber layer, air pressure, load, ambient temperature, road surface, driving style, braking, bike mass etc. Longer service life destroy a tire earlier than frequent driving. In general, a good tire 4000-12000 Kilometer should achieve. Tires where constructive high value was placed on durability and mileage, can also hold up to 20,000 kilometers.

In two-wheeler tires today usually softer materials are used as until the 1980s. This improves the static friction and possibly also the comfort, but at the expense of durability.

The same tire after about 2,500 kilometers mileage ( rear tire )

Tire coding

Similarly, the DOT number can be found in part on bicycle tires, sometimes information on the manufacturing date.

For example, tire manufacturer Continental: In addition to the Vulkanete with the guy lettering is on a tire side a circle. Next to it is a number that gives information about the year of manufacture. The circle itself is divided into four segments in which there are small points. These provide information on the production week, with one point for four weeks stands.

If, for example, of the circle and a 6 ​​in a circle, there are 4 points, then the tire was manufactured in the 16th week of 2006.

Reflective strips

Legislators in some countries (eg in DACH) prescribe light reflectors on the wheels. Here both spoke reflectors ( two per wheel offset by 180 ° ) permissible, as well as through reflective strips that are glued firmly on both tire sidewalls. Due to the high luminosity and the round shape reflective strips are much better than those to detect spoke reflectors, reflective tape but get dirty faster than spoke reflectors and lose over time their first superior reflection intensity. Also spoke clips can attach to fulfill this function.

Admission

In Germany need bicycle tire for road admission, at most they need a possibly applied reflective strips, see § 22a para 1 No. 22 DOT approved. According to Directive R30 of the Economic Commission for Europe, the countries participating in the European Tyre and Rim Technical Organisation ( ETRTO ) are obliged to report that testing organizations test tires and allow. Prerequisite for admission also of bicycle tires is the baked- specifying the metric size designation and the intended air pressure.

Manufacturer

The most common in the German retail manufacturer of bicycle tires are the companies:

• Bontrager (USA), tire manufacturer Trek Bicycle Corporation
• Continental ( Germany )
• Hutchinson ( France)
• Kenda (Taiwan)
• Mavic (France)
• Maxxis (Taiwan)
• Michelin (France)
• Swallow ( Germany )
• Vittoria (Italy )
• Vredestein (Netherlands)

Notbereifung

Due to the demand for rubber for military vehicles Notbereifungen were used as alternatives to air hose tire and solid tire during the world wars in Germany. There were, among others, " Felgenbesätze " from spiral -wound steel sheet, coil spring Tyres, Korkscheibenauflage and beaten rope.