Bicycle tires
Pneumatic tires , which consist of the tire , also called a jacket or cover , and the tube are usually used today as bicycle tires . Together with the bicycle rim , it forms the outer part of the wheel .
The jacket is the outer, robust part of the bicycle tire, it keeps the tire stable against the internal pressure and transfers acceleration, braking and cornering forces to the ground. Usually it is provided with a profile . The inner tube is airtight and has a valve , it maintains the tire pressure. In racing, tubular tires are used in which the jacket completely encloses the tube. The bicycle tires have a significant influence on the smooth running, ride comfort and traction of a bicycle .
history
The first bicycles ( Boneshaker , German: bone shaker) had wooden wheels with iron straps; High bikes from 1870 on were equipped with solid rubber tires on steel rims. With the spread of pneumatic tires from 1888, the mass-produced safety wheels with drive chain, frame geometry and pneumatic tires that are common today, prevailed over high-speed bikes.
Pneumatic tires were first applied for a patent in 1845 by the Scotsman Robert William Thomson , but found little use in four-wheeled vehicles. The pneumatic tire only became popular for bicycles after the Scottish veterinarian John Boyd Dunlop (1888) and the Frenchman Édouard Michelin (1889) patented it for the bicycle at almost the same time . Pneumatic tires for automobiles were later developed on the basis of air-filled two-wheeled tires . The invention of pneumatic tires meant that the high wheels , which were still predominant at the time , were replaced within a few years by the so-called safety low wheel. With this in particular - and with the introduction of the chain or cardan drive on the rear wheel - the bicycles took on their basic design that is common today.
Flaps were still used in Central Europe until around 1995 . The bead sits on the inner edge of the two tire flanks and has the shape of an acute triangle in cross section. When inflated, its flat outer lip slides under the rolled-in sheet metal edge of the rim, anchoring the tire. The bead is much more distinctive than a clincher tire. Bead strips can often be replaced by modern clincher tires if the inner diameter does not exceed the nominal dimension and care is taken that the tire is evenly inserted into the rim all around. When inflating, make sure that the jacket does not slip out of the rim at any point.
Clincher and folding tires
All air-filled tires have a carcass made of fibers that hold the rubber jacket in shape by limiting its elasticity. The density of the carcass fabric is specified with the unit EPI or TPI (Ends / Threads per Inch - "threads per inch").
Clincher tires are the most commonly used. In each of the inner edges of the tire resting against the rim, a single wire ring or a rope made of finer individual strands is incorporated, which forms a bead with the surrounding rubber material. The inside of the rim flange is profiled to accommodate the bead of the shell and hold it in position. These rims are called drop center, clincher or hook rims (English "clincher" ).
Folding tire
Folding tires are a special type of clincher in which the bead wires are replaced by bundles of more flexible aramid threads . This allows the tire to be folded up and stowed away more easily. Folded versions are often 50 to 100 g lighter than the wire versions of the same tire. The rims are the same as for clincher tires. Folding tires can be a bit more difficult to assemble because the tires do not form a ring by themselves.
Balloon tires
Balloon tires are about 50 to 65 mm (2 to 2.5 inches) wide and can be driven with a relatively lower pressure of about 2 bar. The advantage lies in increased driving comfort and good traction on soft surfaces. Wide tires are also less likely to get caught in tram rails. On uneven or soft ground, rolling resistance may be less than narrower tires of balloon tires, since it impacts swallow rather than pass them on frames and drivers or as they sink less deep in snow and sand. On paved roads, on the other hand, the rolling resistance is primarily dependent on the tire pressure.
The company Ralf Bohle (brand Schwalbe ) has registered the term balloon bike for everyday and touring bikes with bulky tires as a word mark and produces balloon tires with a rolling resistance of 2 bar that is no greater than that of conventional 37 mm touring tires inflated at 4 bar. According to a joint study with the Sport University Cologne , the tire air suspension alone achieves almost the same level of comfort as a full-suspension bicycle and even surpasses it in the case of smaller bumps due to the fine response behavior and the suppression of vibration effects.
Balloon tires were already used on cruiser wheels in the 1930s. In the 1960s they reappeared as small 16 ″ tires on compact city bikes from Raleigh and some English folding bikes. On mountain bikes today, tires with widths of around 50 mm (2 inches) are often used as standard tires, but in this case they are rarely referred to as balloon tires.
Fat bike tires
Fat bike tires are around 70 to 150 mm wide and are used on rims with a width of 30 to 100 mm.
Since the 1980s, extra wide tires have been experimented with to reduce ground pressure on snow, sand and other soft surfaces. Tires around 100 mm (3.8 inches) wide on rims with an internal width of 66 mm (2.6 inches) are typical.
Fatbike tires can be used with very low air pressures down to 0.3 to 0.7 bar.
Slicks
Slicks are tires with a smooth tread, the rolling resistance of which is generally lower than that of treaded tires. There is no risk of aquaplaning when cycling and treaded tires do not offer better traction than smooth tires in most riding situations . Since slicks run easier and last longer, they are well suited for use on everyday bikes that are mostly ridden on firm surfaces. Even on damp, smooth surfaces such as asphalt, cobblestones and tram rails, slicks generally do not have any worse grip. In general, profiled tires and knobby tires only have better traction off-road, on sand, gravel and gravel as well as on soft surfaces.
Semi-slicks and studded tires with a center bar
Semi-slicks are a hybrid of slicks and off-road tires. They have a slightly profiled tread or are as smooth as slicks and have a profile on both sides of the tread like everyday tires or even pronounced shoulder lugs like mountain bike tires. While the tread ensures high traction on hard, level ground, the shoulder studs ensure increased traction when the jacket sinks in on soft ground or the air pressure is reduced. According to Sheldon Brown , studded tires with a center bar have a lower rolling resistance than normal studded tires, but they are still noticeably higher than non-profiled tires. The lateral profiling can be useful, especially on the front wheel, in order to improve lateral grip when cornering in the terrain.
Tubeless tires
As with cars and motor cycles there on bicycles and tires that are used without hose - so-called tubeless wheels, even under the English name tubeless known (tubeless). These are usually wire or folding tires that, together with the rim, form a tight air chamber.
The tire bead often has a special shape to better hold the air. To prevent the air from escaping through the spoke holes, a sealing rim tape is stuck to the rim base and the valve is screwed directly into the valve hole. Since conventional jackets are not completely airtight, the tire is filled with a latex emulsion ("sealing milk"), which seals leaks automatically.
Tubeless tires are mainly used by ambitious drivers. Depending on the system, a conventional hose may have to be carried along in the event of a breakdown. After unscrewing the special valve, a commercially available hose can usually be used.
Advantages of the tubeless system:
- Weight reduction as no hose is required
- the tires can be driven with lower air pressure without having to fear hose punctures ("snakebites"); this improves the suspension properties and traction, as well as the rolling resistance on very uneven surfaces,
- A generally slightly reduced rolling resistance is reported, as there is no flexing between the jacket and the hose,
- Reduced risk of breakdowns if a latex emulsion is used, as this can seal small perforations.
Disadvantages of the tubeless system:
- filling with latex emulsion is time-consuming, repairs and changing the tire are often cumbersome;
- the latex emulsion dries over time and loses its sealing effect;
- while when driving with low air pressure can strike through obstacles the rim flange damage;
- tubeless systems require special rims and tires;
- Inflating a deflated tire that has slipped off the rim flange is often only possible with the help of the large air volume flow of a stationary air compressor or a special hand pump with a pressure reservoir. ETRTO recommends deflating the air again after inflating a newly fitted tire in order to be able to determine whether the tire bead sits evenly on the rim in the intended position near the edge.
Winter tires
Many manufacturers offer special winter tires for use in winter road conditions. In some cases, these are tires with a modified tire compound and a changed profile, but winter tires with studs are now becoming increasingly popular . The spikes mostly consist of a thin pin made of hard metal such as tungsten carbide, which is inserted into the tire in an aluminum sleeve. Commercially available clincher tires can also be studded from the inside with pins , screws or blind rivets . Studded tires generally offer good grip even on icy surfaces. The disadvantage is the running noise on dry roads, and weight and rolling resistance are slightly higher than with standard tires.
Other types
Tubular tires
(English: at tubulars "Tubular" ) of the band-shaped sheath is placed around the tube and back sutured. It is glued to the outward-facing hollow of the rim with tire cement or double-sided adhesive tape. With this design, the weight of the wire inserted into the tire bead and the rim flank can be saved. The tires can be inflated with a very high air pressure, which results in a low rolling resistance. However, repairs are time-consuming and time-consuming, which is why tubular tires are usually replaced in the event of a breakdown. The costs for this are mostly only afforded by athletes who take part in competitions. In track cycling tubulars are prescribed clincher can not take the usual there tire pressure of about 10 bar reliable. Tubular tires with almost no profile are used for the bike ball in order to achieve better adhesion to the gym floor.
Tubular tire rims have a rim base that is concave in the rim cross-section without rim flanges and can therefore not be fitted with conventional tires. The mounting bed for the tire consists of a rounded channel with sufficient area for gluing. The tangential tensile stresses ( boiler formula ) of the heavily inflated tire are completely absorbed by the jacket sewn on the rim side, while a normal clincher tire exerts expansion and bending forces on the rim flanges. Light carbon rims are generally only manufactured for use with tubular tires. The rims can also be made from wood.
A disadvantage of tubular tires is that the tire adhesive can heat up during long downhill runs due to the friction of the brake pads on the rim and become soft, so that the tire slips off the rim (for example in the accident of Joseba Beloki at the Tour de France 2003).
In cyclocross tubulars are used almost exclusively. These tires with a slight to medium profile typically have a width of 28 to a maximum of 35 mm. In cross-country races, the traction and suspension properties are driven with very low tire pressure, depending on the nature of the track and the weather, between 1.8 and 3 bar. Since part of the tire cross-section of clincher tires is hidden behind the rim flange , these have a lower free flank height than tubular tires with the same width, so that punctures occur more frequently than with tubular tires with the same air pressure . In addition, the rim flange, which is sharper-edged than tubular rims, is more likely to damage the hose ("snakebite") or will itself be damaged if punctured.
Solid rubber tires
Solid rubber tires are mounted on the same rims that are made for clincher tires. The advantage is the high level of puncture resistance, but this comes at the cost of lower comfort and higher weight. Like tubular tires with high air pressure, hard solid rubber tires partially convert the kinetic energy on uneven ground into impacts directed against the driver, which counteracts their basically good rolling resistance. The assembly of solid rubber tires is often difficult. Since they are not pressed against the rim flank and stabilized by the air pressure, they have to be very tight. Solid rubber tires were the forerunners of today's pneumatic tires, they were in use between 1880 and 1890. The idea of solid rubber tires kept coming up, but it did not catch on because of the predominant disadvantages.
PU foam tires
A newer alternative to solid rubber tires are tires made of PU foam , which are offered by several manufacturers. Manufacturers are e.g. B. Tannus, Britek and Hutchinson and Lenco with the Primo brand.
Early airless tires and emergency tires
Due to the need for rubber for military vehicles, during the world wars in Germany and the shortages shortly after the end of the war, emergency tires that managed entirely without rubber were widespread. Among other things, there was "Felgenbesätze" of helically wound steel sheet, coil spring tires, cork disc pad and beaten rope.
In contrast, airless tires consist of a tire casing that sits on the rim or similar spacers via resilient elements. John Boyd Dunlop had the first patent on such tires as early as 1886, two years before the pneumatic tire was patented.
material
The rubber compound from which the tire is made should combine different, sometimes competing properties: low rolling resistance, high grip, low abrasion, long durability, stable studs.
Special attention is always paid to the trade-off between low rolling resistance and good wet grip. Good adhesion results from a soft rubber compound, which, however, also increases rolling resistance due to its increased internal friction. A good compromise is achieved, for example, with the filler silica . By using several rubber compounds (dual and triple compound technology), high-quality tires attempt to combine good cornering grip with low rolling resistance when driving straight ahead. Winter tires are made with softer rubber compounds in order to achieve the best possible grip at low temperatures. Tires for use on ice and hard snow are offered with incorporated spikes .
In the past, the inside of the tire was sprinkled with talc (a finely ground, natural magnesium silicate containing crystal water ) to prevent the tire and tube from sticking together . Today the hoses are equipped with a thin layer of talc at the factory.
Tire and rim sizes
To use a speedometer and distance meter on the bike, the circumference of the tire must be taken into account.
Size information
The previously common size specifications on bicycle tires were made inconsistent. Some sizes do not correspond to the usual pattern and cannot be converted to one another.
The general rule:
- Bicycle tires are traditionally named after the outer diameter and width of the tire . The outside diameter is specified in inches. The width is given in inches or in millimeters. One inch is 2.54 cm.
- In contrast, moped, motorcycle and car tires are usually named after the outer diameter of the rim shoulder (the rim base) on which the inner diameter of the tire rests.
- Since it was not always easy to identify the ability to combine bicycle tires and rims according to previous usage , both are now uniformly designated according to the outer diameter of the rim shoulder according to the new ETRTO guidelines . This corresponds to the inner diameter of the tire that sits on the rim shoulder. For the rim, the internal width is also mentioned, for the tire, the width.
Mountain bike rims typically have an internal width of 17 mm. As with touring bikes, 19, 21 and 23 mm wide rims are also available. The tire width should be between one and a half and three times the inner width. Wide tires tend to break on narrow rims. The durability of the tire can increase significantly if the tire width is limited to two to two and a half times the inner width.
| Tire dimensions | ETRTO | Inch as a decimal number | Inches as a fraction | French indication |
|---|---|---|---|---|
| exemplary size specifications for tires with a similar width that each fit on a 622 rim | 37 - 622 width - inside ∅ |
28 × 1.40 outer ∅ × width |
28 × 1 5 / 8 x 1 3 / 8 outdoor ∅ × height * x width |
700 × 35C outer ∅ × width / height |
| Outside diameter tire | - | approx 28 inches | approx 28 inches | approx. 700 mm |
| Inner diameter tire = nominal rim diameter | 622 mm | - | - | - |
| Tire height | - | - | about 1 5 / 8 inches | C ≈ 39 mm |
| Tire width | approx. 37 mm | approx 1.4 inches | about 1 3 / 8 inches | approx. 35 mm |
|
* In contrast, the FUB defines the customs information on its side in the order outside∅ × width × height
In rare cases the diameter was given in millimeters and the width in inches. That was not taken into account here. |
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Size information for moped tires
Bicycle trailers and cargo bikes are occasionally equipped with particularly resilient moped tires. The size specification of these tires and tubes is misleading, as it is inconsistent either according to the outer diameter of the tire (corresponding to the # inch specification for bicycles) or the nominal rim diameter in inches (as for motorcycles and motor vehicles ).
Motorcycle tires were traditionally referred to as the tire width (in inches and often written as a fraction ) and the nominal rim diameter in inches (usually in this order; e.g. 2 1/4 - 16).
Both moped tires and the associated tubes are alternatively named according to the traditional designation in the bicycle sector , namely according to the outer diameter of the tire in inches and the tire width in inches as a decimal number (usually in this order; e.g. 20 × 2.25).
If the ETRTO designation cannot be found out, compliance can often only be properly ensured if the size is specified in exactly the same notation on the tire and tube. This means that the diameter is either in front of or after, the width is given either as a fraction or as a decimal number and there is either a hyphen or an "x" between the two. Some manufacturers also give both names. Sometimes the specification of the tire outer diameter is marked as "new" and that of the nominal rim diameter as "old".
| Abbreviation (according to the outer tire diameter ) in inches |
French short name |
Nominal rim diameter / inner tire diameter according to ETRTO in mm 1 |
|---|---|---|
| 10 " | - | 152 |
| 12 " 12.5" |
- | 203 |
| 14 " | 350 350A |
288 298 |
| 16 " | - 400 400A |
305 330 340 |
| 18 " | - - - 450A |
349 355 357 2 390 |
| 20 " | - 500A - 500 - |
406 438 440 451 460 |
| 24 " | - - 600 / 600A |
507 540 541 |
| 26 " | 650 650C 650B (27.5 ") |
559 571 3 584 |
| 27 " | - | 630 |
| 28 " | 700D 700 / 700C 700B 700A |
587 2 622 4 635 642 2 |
| 29 " | - | 622 4 |
|
1Popular sizes are fat represented
2 hardly widespread in Germany
3less common; z. T. with GDR bikes
4th 622 mm rims are used for both 28 "and 29" tires.
|
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Inches
Variants:
-
Tire outer diameter × tire width
Example: 28 × 1.40
The first number indicates the approximate tire outer diameter, the second indicates the approximate tire width. In common parlance, mostly only the tire outer diameter is given; one speaks for example of a "26er wheel".
-
Tire outer diameter × height × tire tire width
Example: 28 × 1 5 / 8 x 1 3 / 8
An indication of the width takes place in a fractional or decimal notation.
The actual outer diameter of the tire can differ significantly from the inch specification.
The 29-inch mountain bike tires introduced around 2012 can be used on the same rims as the popular 28-inch tires. The size specification “29 inches” is intended to express that the voluminous mountain bike tires of this size have a larger outer diameter than the 28-inch tires that have been common up to now.
| indicated on tires | 24 ″ | 26 ″ | 27 ″ (tubular) | 27.5 ″ | 28 ″ | 29 ″ | |
| Rim size colloquially | 24er | 26er | 27er | 27-5er | 28er | 29er | |
| Rim size according to ETRTO | mostly 507 | often 559 or 571 | 630 | 584 | 622 | 622 | |
| actual outer ∅ of the tire (the size printed on the tire is given in brackets; however , the tire width may vary, it is only given here as an example) |
from | 23.9 ″ (47-507 or 24 × 1.75 × 2) |
24.7 ″ (23-571 or 26 × 1) |
26.5 " (18-630) |
26.0 ″ (35-584 or 27.5 × 1.35) |
27.2 ″ (32-622 or 28 × 1.25) |
28.6 ″ (50-622 or 29 × 2.00) |
| to | 24.4 " (37 to 540 or 24 x 1 3 / 8 ) |
26.6 ″ (57-559 or 26 × 2.125) |
27.8 " (32 to 630 or 27 x 1 1 / 4 ) |
29.0 ″ (75-584 or 27.5 × 3.00) |
28.5 ″ (47-622 or 28 × 1.75) |
29.5 ″ (60-622 or 29 × 2.35) |
|
French name
Variants:
-
Tire outer diameter and abbreviation for tire height
Example: 650A
The so-called French designation consists of a three-digit number and usually an appended letter. The number indicates the approximate outer diameter of the tire in millimeters. The letter names the matching nominal rim diameter and thus indirectly indicates the height of the tire:
A ≈ 30 mm
B ≈ 33 mm
C ≈ 39 mm
For the example, the tire inner diameter / rim diameter is 650 mm - 30 mm - 30 mm = 590 mm. A 650C tire then fits, for example, on a rim with a 571 mm diameter (650 mm - 39 mm - 39 mm = 572 mm). All 650s are 26-inch tires (650 mm / 25.4 ≈ 26 inches). -
Tire outer diameter, tire width and abbreviation for tire height
Example: 650 × 35A
The additional two-digit number indicates the tire width in mm. The letter indicates the nominal rim diameter that matches the tire.
ETRTO
According to ETRTO (European tire and rim expert organization), the tire width followed by the inner diameter of the tire are given in millimeters. The latter corresponds to the nominal diameter of the rim at the point where the tire rests on the rim base.
Example: 47 - 622 stands for:
- Tire width: 47 mm
- Inner tire diameter or nominal rim diameter: 622 mm
A 47-622 tire only fits on a 622 rim. Recommendations are also given as to which inner width of the rim should be combined with the tire width of 47 mm (see table below).
Modern bicycle tubes are flexible enough to be used with different sized coats. The manufacturers specify the range of tires that match the tube by specifying the smallest and largest recommended dimensions - separated by a slash.
Example: 32/47 - 609/642 stands for:
- Minimum tire width: 32 mm
- Maximum tire width: 47 mm
- Minimum inner tire diameter or nominal rim diameter: 609 mm
- Maximum inner tire diameter or nominal rim diameter: 642 mm
The outside diameter of the entire impeller cannot be read from the ETRTO specification. Since clincher tires are generally only slightly taller than they are wide, the minimum dimension of the outer diameter can be estimated by adding twice the tire width to the inner diameter. The ETRTO has only defined tire sizes with a certain degree of distribution; The ETRTO does not give any comparative values for some rare tire sizes.
| Inner width of the rim [mm] |
recommended by the ETRTO
Tire widths [mm] |
|---|---|
| 13 | 18-25 |
| 15th | 23 - 32 |
| 17th | 25 - (37) * 50 (52) ** |
| 19th | 28 - (47) * 57 (62) ** |
| 21st | 35 - (50) * 62 |
| 23 | 37 - (50) * 64 |
| 25th | (42) ** 44 - (60) * 64 |
| 27 | 47-64 |
| 29 | (52) ** 54-64 |
| Wide balloon & fat bike tires *** | |
| 30th | 65-75 |
| 35 | 65-75 |
| 40 | 65-75 |
| 45 | 70 - 75 |
| 50 | 70 - 75 |
| 65 | 100 |
| 70 | 100 |
| 75 | 100-110 |
| 80 | 100-120 |
| 85 | 110-120 |
| 90 | 110-120 |
| 100 | 120 |
|
*The information in brackets corresponds to the former
ETRTO recommendation until 2006.
**The information in brackets comes from Schwalbe and
Mavic and may differ from the ETRTO information.
*** The information comes from Schwalbe
|
|
Ratio of tire to rim width
The table opposite names the pairings of tire width to rim width recommended in the ETRTO standard.
Depending on the internal width of the rim, a range of tires of different widths can be fitted. However, not every width ratio makes sense. Tires that barely wider or even narrower than the rim, have little resilience and tend at low air pressure to breakdowns . Particularly wide tires can overload the rim flanks when the air pressure is high. With low air pressure, wide tires can cause spongy driving behavior and in extreme cases even break out.
The heavily loaded tires on tandems , cargo bikes or touring bikes should be selected according to the more restrictive ETRTO recommendations, which were valid until 2006. Otherwise, the tires tend to wear out prematurely on the tire sidewall, as this is bent directly on the rim edge and stressed by flexing. In case of doubt, the tire width should be limited to twice the inner rim dimension (nominal dimension) .
A wide (mountain bike) tire on a rim that is too narrow can lead to characteristic short cracks on the inside of the tube in the area of the spoke nipples. The reason is probably that the tube first fills the large, concentric cross-section of the tire when it is inflated and is only then pushed down into the narrow rim base. The area of the tube facing the rim is overstretched and prone to any unevenness in the rim base. The slight bulging of the rim tape over the spoke nipples then leads to the formation of cracks due to overstretching. After removing the defective hose, the curvature of the spoke nipple can be seen on the inside, with the damaged area in the form of a fine slit in the center.
When combining large-volume casings with narrow rims, brand-new tubes that have been approved by the manufacturer for the widest possible tires should be used. Lightweight hoses as well as hoses that have been stored for a long time should be avoided, as the rubber loses its elasticity over time.
Occasionally, it is recommended to use a particularly stiff rim tape made of hard plastic or to apply talcum powder to the inside of the tire sidewalls to make it easier for the tube to slide and spread evenly towards the rim. The effectiveness of these measures is controversial.
Air pressure
The permissible internal pressure is usually indicated on the tire sidewalls in different units, e.g. B. in bar , PSI or kPa . In principle, narrower tires require higher tire pressure.
The correct tire pressure can be determined as follows:
- Inflate the tire until it can only be pushed in a little with your thumb.
- Then load the tire with the normal weight of the driver and luggage. The sidewalls of the tire should only bulge slightly.
- If the front wheel is slowly driven over the edge of a curb without the driver shifting his weight or making the climb easier by pulling on the handlebars, the rim must not sit on the curb. The tire must be able to absorb the impact without bottoming out .
- Comparison of the reading on a manometer with the maximum pressure indicated on the tire. A slight excess of the maximum pressure is usually harmless with a new tire. If the tire is aged, too high pressure can shorten its service life. Stretch cracks form in the rubber and the tire can bulge. In rare cases the tire can slide off the rim. The hose then often pushes its way through the gap and bursts. Even under high loads, as occurs with cargo bikes, tandems and touring bikes, the maximum pressure should, if possible, not be exceeded in order to increase the service life. Too low a pressure, on the other hand, increases the risk of bottoming out and breaking away when cornering.
Aspects when choosing tire pressure:
- The suspension comfort of otherwise unsprung bikes depends crucially on the air pressure and the tire thickness. The higher the pressure, the more directly impacts are transmitted to the frame and driver.
- As the tire pressure falls, the flexing work of the tire increases and thus its rolling resistance . If the pressure is too low, the service life of the tire is also reduced because the sidewalls of the tire are more stressed and brittle more quickly. On the other hand, on very uneven ground and gravelly roads, the rolling resistance can even decrease, since a weakly inflated tire can roll over bumps better. The fewer shocks transmitted to the frame and must be from the back of the driver, the less kinetic energy is expended for accelerating the bicycle and rider vertically. If the bike is equipped with a suspension, the impact energy is absorbed by the suspension damper. The rolling resistance can also be reduced on a very flexible surface, as a weakly inflated tire flattens more and sinks less deeply into the surface due to the enlarged surface.
- Low pressure leads to better traction (power transmission) away from paved roads , as a flexible tire has a larger contact area with the ground, especially on loose material such as sand, gravel, gravel and snow.
- If the pressure falls below a certain level, the stability is reduced in inclined positions. The bike “floats” in bends, i. H. it moves to some extent transverse to the direction of travel; Driving behavior and driving safety deteriorate. The thin flanks of voluminous mountain bike tires can fold in when the air pressure is too low when cornering, causing the tire to suddenly give way and control of the wheel can be lost. The buckling and creasing of the tire sidewalls leads to premature breakage of the rubber compound and ultimately the carcass .
- Low pressure can cause the tire to wander lengthways on the rim. Since the tube usually moves with the tire, it slides over the fixed valve from behind when braking and wrinkles itself. There is also the risk of the valve tearing off.
- The correct air pressure depends on the body weight and possibly the load on the bike. In order to reduce the risk of a breakdown when driving over sharp-edged obstacles, the air pressure should also be increased if the weight is higher. (See also the section above.)
- The air pressure depends to a small extent on the ambient temperature (see thermal equation of state of ideal gases , gas laws ).
- The load on the rim flanks depends on the air pressure and the tire width. The force acting on the flanks of the rim is proportional to the product of tire pressure and tire width. If the tire pressure remains the same, wider tires exert a higher force on the rim. By adhering to the ETRTO recommendation for the combination of rim width and tire width , overloading of the rim flange is avoided. For some lightweight rims, the manufacturer specifies the maximum permissible air pressure depending on the tire width.
Tire pressure according to bike type:
- When it comes to mountain bikes , the focus is on traction and suspension. The pressure in the area is between 2 and 4 bar; for tubeless tires 1.8 to 2.5 bar. The flanks of large-volume mountain bike tires (from around 2 ″ or 50 mm wide) are often made thin and flexible. As a result, the tires can be driven with low air pressure without the tire flanks wearing out due to the stronger flexing movement. To improve traction on steep descents, the air pressure should be selected so low that bottoming out is just avoided.
- For touring and trekking bikes , rolling resistance and puncture resistance are particularly important. The pressures here are between 3.5 and 6 bar.
- Racing bikes with clincher or tubular tires are usually ridden with 7 to 9 bar on the road. On track bikes , pressures between 10 and 13 bar are common, and higher pressures are also common on record runs. From a pressure of around 14 bar, the tire is considered “pumped to death”, which means that it hardly cushions shocks, while the rolling resistance no longer significantly decreases.
- Two-wheeled bicycle trailers and tricycles do not lean to one side when cornering. The air pressure should not be too high, otherwise the middle of the tread will wear out a lot, as it is always in contact with the ground. The tires are never completely parallel to each other. Thanks to the slight toe-in, hard-inflated tires rub against the road surface with every revolution. Tires with lower air pressure are more flexible and therefore wear more slowly if they are not precisely parallel to each other. After all, inflated tires that are too hard make the bicycle trailer jump in an uncontrolled manner on uneven surfaces if it is not fully loaded. It is therefore advisable to always have a pump with you so that the tire pressure can be adjusted to the weight of the load at any time.
handling
It makes the assembly of the tire and tube easier if the tube is initially inflated slightly. This also reduces the risk that the hose will get damaged between the assembly tool and the rim when tightly fitting jackets are pulled on.
Before fully inflating, the valve should be pushed back through the rim hole towards the tire to ensure that the tube is not pinched between the tire wall and rim at this point. In addition, it should always be checked during inflation whether the tire bead is evenly deep in the rim all around. Otherwise there is a risk that the tire wall will slip off the rim flange when inflating. In this case, the tube can form a bubble and burst.
ETRTO recommends that the tire beads be coated with a small amount of soap solution or another oil- and grease-free lubricant before assembly. This practice is more common for car and motorcycle tires than for bicycles, but it can facilitate the assembly of the tires (without damaging the beads or the tube) and possibly improves the even fit of the beads in the rim flange. However, not too much lubricant should be used to prevent the tire from slipping on the rim.
The repair of tires and inner tubes is described in the article tire defect .
durability
The mileage as well as the service life of the tires vary greatly with the rubber compound, thickness of the rubber layer, air pressure, load, ambient temperature, road surface, driving style, braking behavior, bicycle mass, etc. Longer idle times destroy a tire earlier than frequent driving. As a rule, a good tire should reach between 4,000 and 12,000 kilometers. Tires that are designed with a high level of durability and mileage can last up to 25,000 kilometers under heavy luggage.
Mostly softer materials are used in two-wheeled tires today than they were until the 1980s. This improves the static friction and possibly also the comfort, but at the expense of the durability.
Breakdown security
In principle, the puncture resistance depends on the rubber compound, the tire thickness, the density (TPI) and the type of threads in the fabric of the carcass and the air pressure. With low air pressure foreign objects penetrate more easily, with higher air pressure they are more likely to be displaced when rolling over.
There are tires with a band of aramids , nylon or rubber vulcanized all around the tread area , with rubber increasing the rolling resistance. This prevents the penetration of glass, thorns and other foreign bodies through the running surface. This puncture protection works reliably for foreign bodies that penetrate through the tread, the tire sidewalls have no reinforced protection. The disadvantages of this puncture protection are the higher price and harder structure with the same air pressure.
The profile and rubber compound can also affect breakdown frequency. The type of profiling of the running surface as well as “sticky” rubber compounds can promote the adhesion of small split, gravel or glass fragments (“cullet collectors”). Over time, these foreign objects can damage the carcass. The tires should therefore be freed from such fragments on a regular basis.
See also the ratio of tire to rim width section above and the solutions described in the flat tire article .
Tire coding
Similar to the DOT number on car tires, information on the date of manufacture can sometimes also be found on bicycle tires.
For tires from the manufacturer Continental, for example, the following applies:
next to the Vulkanette with the type lettering, there is a circle on one side of the tire. Next to it is a number that provides information about the year of manufacture. The circle itself is divided into four segments with small dots indicating the month of manufacture. One point stands for one month.
For example, if there is a 6 next to the circle and there are 4 dots in the circle, then the tire was produced in April 2006.
Reflective strips
The legislators of some countries ( e.g. in DACH ) prescribe light reflectors on the wheels. The following are permitted:
- Yellow-orange spoke reflectors (two pieces per wheel offset by 180 °)
- White, continuous reflective stripes on both sides of the tire. Reflective strips are initially much easier to see than spoke reflectors, but they get dirty more quickly
- Reflective spoke clips in sufficient number (according to manufacturer information)
Admission
In Germany, bicycle tires do not need a license for road traffic, see Section 22a Paragraph 1 No. 22 StVZO . According to guideline R30 of the Economic Commission for Europe , the participating countries are obliged to report to the European Tire and Rim Technical Organization (ETRTO) which testing organizations test and approve tires. The prerequisite for the approval of bicycle tires is the baked-in indication of the metric size designation and the intended air pressure.
Manufacturer
The most popular manufacturers of bicycle tires in the German trade are the companies (country information refers to company headquarters, not to production site):
- Bontrager (USA), Trek Bicycle Corporation tire manufacturer
- Continental AG (Germany)
- Hutchinson (France)
- Kenda (Taiwan)
- Mavic (France)
- Maxxis (Taiwan) the
- Michelin (France)
- Nokian (also: Nokia) (Finland), mostly winter tires
- Prophete (Germany)
- Schwalbe ("Ralf Bohle GmbH", Germany)
- Heidenau tire factory , manufactured Pneumant tires from 1969 to 1994 , continuing to specialize in two-wheel and special diagonal tires
- Vittoria (Italy)
- Vredestein (Netherlands)
Individual evidence
- ↑ history of the bicycle , fahrradmonteur.de
- ↑ Ralf Bohle : What does the EPI number mean for the carcasses? Swallow, accessed November 28, 2013.
- ↑ a b Knowing what makes you fast , article in the mountain bike magazine about a thesis by Peter Nilges
- ↑ Tire width and rolling resistance - a persistent rumor , fahrradmonteur.de
- ↑ Ulf Hoffmann: Bicycle repairs. 2nd Edition. Stiftung Warentest, 2016, ISBN 978-3-86851-437-7 , p. 98.
- ↑ Registration of the word mark Balloonbike , In: Register.DPMA.de
- ↑ "Balloonbike": New type of bicycle conquers the market (May 12, 2005)
- ↑ Internet page on Balloonbikes from Ralf Bohle, In: www.Schwalbe.de
- ^ Bicycle Tires and Tubes , Section "Hydroplaning" and "Tread patterns", In: SheldonBrown.com; accessed in March 2020.
- ↑ Hans-Christian Smolik, Stefan Etzel: The large bicycle lexicon: Technology - Material - Practice from A to Z. 1st edition. Bielefelder Verlags-Anstalt, 1997, ISBN 3-87073-127-3 , p. 451, p. 481.
- ^ Bicycle Tires and Tubes , Section "Combination Treads", In: SheldonBrown.com; accessed in March 2020.
- ↑ Ulf Hoffmann: Bicycle repairs. 2nd Edition. Stiftung Warentest, 2016, ISBN 978-3-86851-437-7 , p. 97.
- ↑ "ETRTO RECOMMENDATIONS - EDITION 10 MARCH 2016.docx" or "ETRTO RECOMMENDATIONS - EDITION 10 MARCH 2016.pdf", p. 60f, available on the ETRTO website under the menu item "Recommendations - Free Download" or "Recommendations"
- ↑ Description of winter tires on Fahrradmonteur.de
- ↑ What should you know about studded tires? Retrieved December 27, 2018 .
- ↑ Instructions for making winter tires with blind rivets, in English; Instructables.com
- ↑ Advice on buying and manufacturing winter tires , Icebike.com - When using screws or blind rivets, holes should be drilled beforehand or pricked with an awl . Is recommended u. a. the use of short drywall screws. Before riveting, blind rivets should be provided with washers from the outside to ensure a good hold in the jacket. To protect the hose, the heads of screws or rivets should be covered with adhesive tape.
- ↑ Suggestions to improve traction in winter, in English; Bikehacks.com
- ↑ Solid rubber tires , Fahrradmonteur.de
- ↑ The fascination of bicycles. History - technology - development . Moby Dick, Kiel 1997, ISBN 3-89595-118-8 ; Delius Klasing, Bielefeld 2007, ISBN 978-3-7688-5253-1 .
- ↑ a b c Georg Böger: Technical tips: tires and rims , section "" Standard "with consequential damage", May 2000.
- ↑ a b c Arno Welzel: Permissible combinations of tires and rims according to ETRTO
- ↑ a b extensive tire size table on schwalbe.de
- ↑ a b Tire dimensions on the side of the FUB (Fédération française des usagers de la bicyclette), similar to the ADFC
- ↑ Sometimes the rim size is also printed on, which should then correspond to the tire designation. Instead of 2.25 ", 2 1/4" is sometimes given.
- ↑ Tire sizes of current models ( Memento from November 4, 2014 in the Internet Archive ) on sigmasport.de . In the right red column the tire circumference is given in mm. The actual diameter in inches can be calculated using the formula d (in) = U (mm) / (pi * 25.4).
- ↑ a b Tyler Benedict: Tech Talk: Are your bike tires too wide for your rims? Here's how to get it right , In: BikeRumor.com, August 2016.
- ↑ Table "Which tire fits which rim" , in the internet offer of "Schwalbe", Ralf Bohle GmbH
- ↑ The opinion is rarely held that the tire's adhesion to the rim is significantly reduced if talc gets into the area between the tire flank and the rim, so that the tire and tube shift on the rim when braking and, in the worst case, the valve could tear off .
- ↑ required air pressure depending on the tire width , fahrradmonteur.de
- ↑ a b see forum posts by a chassis engineer with the user name “jolly63” from April 20 and 24, 2019 on the subject of “ front wheel ”; In: Pinoforum.de
- ↑ If the impacts are "swallowed" by the tire, part of the impact energy is translated into flexing work and, as with shock absorbers, is lost in the form of heat, while another part is converted back into kinetic energy by the rebounding tire.
- ↑ Research by T. Senkel, A. Hauschild et al. of the University of Oldenburg: Plea for a good tire , see there the paragraph under Figure 3
- ^ Bicycle Tires and Tubes , Section "Trikes and Tricycles", In: SheldonBrown.com; accessed in March 2020.
- ↑ "ETRTO RECOMMENDATIONS - EDITION 10 MARCH 2016.docx" or "ETRTO RECOMMENDATIONS - EDITION 10 MARCH 2016.pdf", p. 59f, available on the ETRTO website under the menu item "Recommendations - Free Download" or "Recommendations"
- ↑ Peter Smolka on a world tour: Reifer Reifen , tour-de-friends.de
- ↑ Ralf Bohle: Why is the air pressure so important in bicycle tires? schwalbe.com
- ↑ Tire construction. (No longer available online.) Continental Reifen Deutschland GmbH, archived from the original on March 28, 2016 ; accessed on April 4, 2019 .
literature
- Walter Euhus : The history of bicycle tires . Historic bicycles e. V. , Langenhagen 2003, ISBN 3-9807011-2-3 .
- Michael Gressmann, Franz Beck, Rüdiger Bellersheim: specialist knowledge of bicycle technology. Verlag Europa-Lehrmittel, Haan-Gruiten 2006, ISBN 3-8085-2291-7 .
- Fritz Winkler, Siegfried Rauch: Bicycle technology repair, construction, production. 10th edition. BVA Bielefelder Verlag, Bielefeld 1999, ISBN 3-87073-131-1 .
Web links
- Repairing bicycle tires - instructions at pdeleuw.de
- Technical information about bicycle tires on the homepage of the manufacturer Ralf Bohle GmbH ("Schwalbe")
- Tire and wheel sizes on fahrradmonteur.de
- Tire and wheel sizes (French)
- Youtube video about the manufacture of a bicycle tire