Technical information FITTING ORDER: Check the rim for sharp edges or damaged areas. Centre the rim tape correctly. Hold one side of the tyre against the rim. Place the inner tube in position, slightly inflated, make sure if not twisted. Starting at the valve, push the tyre by hand, correctly on the rim. Press valve in the tyre, inflate the tube and fasten by hand the under valve nut. Keep the tyre well mounted in the rim. Keep the tyre at correct pressure, this reduce wear and will make pedalling easier. ROLLING RESISTANCE AND BREAK THROUGH STRENGTH. a hard metal or synthetic wheel has the lowest rolling resistance on a flat surface. but, as soon as any unevenness occurs in or on the flat surface, hard wheels face a lot of hindrance. there is as it were a conflict between the edges and/or ridges that cause this unevenness. for example cobbles and concrete tiles never lie completely flat. this also applies to asphalt and concrete to a lesser extent. concrete is available in different grades of coarseness: think of inside and outside floors. the rolling resistance increases quickly on an uneven surface as a result. a soft rubber or synthetic wheel and a rubber inner tube have a larger rolling resistance on a flat surface, but will easily take any small unevenness, whilst the rolling resistance only increases to a little extent. ROLLING RESISTANCE OF CYCLE TYRES. here it is of utmost importance that the tyre flexes well and easily at both the surface and the working surface. after all the tyre must constantly change shape. the tyre is round and the small area that makes contact with the road is flattened. the lower the tyre pressure, the larger this area and thus a higher rolling resistance results. the rougher the road you are riding on, the more the tyre must bend and more often too. on a tyre where the working surface bends, the rolling resistance will increase more than with a working surface that bends easily. you can make the tyres very thin and thus make them run lightly, but then they always get punctured. then again, if you solve this with a breaker layer, then you must aim for a synthetic layer of 3mm at least. thus the first tyres were made with a breaker layer. now most brands have brought this layer down to 0.5 to 1.5mm so that the tyres are hardly more punture-proof than a normal tyre. we have succeeded in combining an extremely puncture-proof tyre with a low rolling resistance through the new and very special build of this tyre and the use of new materials. this applies to different surfaces such as roads, paths, asphalt, cobbles, tiles, shells and slag. we have based this on averages, although this can of course differ between cyclists. asphalt 70%, cobbles 15%, tiles 5%, shells and slag combined 10%. now how does one determine the rolling resistance? if we consider asphalt as a flat surface, then we can measure this on a flat or a smooth roll. with cobbles and tiles the normal unevenness lies between 3 and 7mm if we measure this on a roll with 5mm high strips. the average rolling resistance of the flat roll x 60 and the average rolling resistance of the roll with strips x 30, add these up and divide by 100, then we have the real average rolling resistance. using this measurement method we determined the following rolling resistance.coefficient. DUTCH PERFECT NO FLAT TYRE 0.00590 - 0.00600 VREDESTEIN PERFECT OLD 0.00610 - 0.00620 (THICK BREAKER LAYER) SAWHNEY PPS LONG-LIFE 0.00690 - 0.00710 (THICK BREAKER LAYER) this measurement gives some indication, but is not fine enough to measure the exact rolling resistance. we have therefore chosen another measuring method. measurement using a small three-wheeled cart that rolls down a slope. always using the same slope, the same weight and the same wheels, gives reliable data. see the rolling resistance measurements below: measured by a.p.j. hoge (civil engineer) measurement conditions measured by s.t.c. measurement conditions roll out measuring apparatus 3-wheeled measuring cart roll out measuring apparatus 3-wheeled measuring cart measurement p/tyre repeated 3x: difference 2% measurement p/tyre repeated 3x: difference 3.5% load per wheel: 500n or 50kg. load per wheel: 500n or 50kg. road surface measured section: smooth concrete road surface measured section: rough concrete measured inside measured inside hubs measuring wheels: type ideale bitex hubs measuring wheels: type ideale bitex. inner tube: butyl dutch perfect inner tube: butyl dutch perfect tyre pressure: 4 bar tyre pressure: 4 bar. tyre and temperature of surroundings12 C tyre and temperature of surroundings 15 C the same wheels and tyres were used for both measurements. rolling resistance coefficient rolling resistance coefficient vredestein perfect prs 28" 0.00514 vredestein perfect prs 28" 0.00556 schwalbe marathon comfort 28" 0.00595 schwalbe marathoncomfort28" 0.00599 michelin altika 28" 0.00538 michelin altika 28" 0.00558 continental top touring 2000 28" 0.00561 continental top touring2000 0.00579 dutch perfect no flat tyre nr.99/86 28" 0.00592 dutch perfect no flat tyre nr 99/86 28" 0.00595 as you can see the difference in rolling resistance of the well-known brands are very small and there is sometimes a tiny difference per tyre of the same brand. this is around 5%. there is also a tiny difference per measurement: the reproducibility lies between 2 and 3.5%, the tolerancy is about 8%. note: keep the tyre pressure right: 3.5 tot 4.0 bar. this produces a low rolling resistance and increases durability. break through strengh: all the brands with a breaker layer can meet the standards set. the standards are set so low that tyres without a breaker layer can meet the set standards as well. a needle is placed against the tyre at a pressure of 80n or 8 kg, and this needle must not go through it. this is the statistic test or stationary test. in the dynamic or moving test the needle is applied at 40n or 4 kg with pulses or blows (1 per second) and may not go through before 30 pulses or blows. but if you're on your bicycle then the pressure on the tyre is not 4 or 8kg but 10 times as much. just work it out. if you weigh 80 kg then your weight, including that of the bicycle, produces about 40kg on the front wheel and about 50 kg on the rear wheel. with luggage this can easily reach up to 80 kg a breaker layer is by no means able to withstand sharp objects such as glass, chippings, thorns or drawing pins on the other hand the no flat tyre is able to resist such sharp objects. placing the 5mm flexigum layer directly under the working surface does this. this very tough layer absorbs small sharp objects and then rejects them. thorns can penetrate here however, but come against the underlying breaker layer and break off. a drawing pin does not penetrate because of the thick layer. that is why this is the first bicycle tyre with a no-puncture guarantee. measurement results: see table note: the necessary bicycle power 1) is described well in the following formula: p=(m*g*rw*v+0.5*sml*a*cw*v^3)r where: p is in watts m= each cyclist's weight in kg. g= 9.81 m/s^2 rw= rolling resistance coefficient v= speed of cyclist in m/s. sml= specific air mass in kg/m^3 is 1.2. a= wind capture cyclist's area plus bicycle in m^2. cw= air resistance coefficient r= efficiency chain transmission for a hybrid bicycle (sitting upright) for example the average values are: m=100 kg rw=0.006 v=5.5m/s^2 sml=1.2 a=0.9m^2 cw=0.8 r=0.9 then: p = 116 watt. with a change in the rolling resistance coefficient from 0.006 to 0.005 for example then p=110 watt. the air resistance dominates the rolling resistance strongly, as one can see, even at low bicycle speeds.