Änderungen

Aus Fahrradmonteur
Zur Navigation springenZur Suche springen

Vorlage:Reifenbreite und Rollwiderstand/Physik (bearbeiten)

Version vom 29. November 2012, 14:25 Uhr

1.799 Bytes hinzugefügt ,  vor 12 Jahren
keine Bearbeitungszusammenfassung
;Abrollwiderstand:
Auch vor dem Reifen bildet sich ein Wulst [...], der den Aufstandspunkt des Reifens leicht nach vorne verlagert. Das Rad muß also ständig über seinen Wulst abrollen, der eine kleine Kippkante darstellt. [...] Der "Rollwiderstandsbeiwert" [...] hat für normale Fahrradbereifung bei 28-Zoll-Laufrädern und 4 bar Luftdruck einen Wert von etwa 0,01, der sich bei guten Rennreifen (Continental "Olympic) und 8-9 bar Luftdruck auf etwa 0.002 reduziert.
===Sheldon Brown<small><ref>[http://sheldonbrown.com/tires.html#rolling Bicycle Tires and Tubes], Rolling Resistance </ref></small>===
There are four ways to reduce this friction, each subject to trade-offs:
 
The thinner and softer the rubber/fabric of the tire are, the more flexible they become.
 
The trade-off with this is that the thinner the tire gets, the more fragile it is, and the sooner it will wear out.
The higher the air pressure, the less the tire will deflect.
 
The trade-off with this is that if you pump the tire up too hard, you lose the benefits of pneumatic tires: the ride becomes excessively harsh, and traction will be reduced. In addition, extremely high pressures require a stronger (heavier) fabric and stronger (heavier) rim flanges.
 
When riding on a smooth surface, rolling resistance does decrease theoretically with any increase in pressure, but with modern, high-quality tires the rolling resistance at correct inflation pressure is already so low that the infinitesimal reductions gained are more than outweighed by the trade-offs.
 
In practice, riding surfaces aren't perfectly smooth, and overinflation actually increases rolling resistance, due to vibration.
Radial plies let the tread lie down flat without scrubbing. This is why radial-ply car tires wear longer. As already described, though, radial-ply tires have less lateral stability than bias-ply tires. Also, as Jobst Brandt has pointed out, a large-diameter, small cross-section bicycle tire has much less scrub than a car tire.
A belt under the tread also helps the tread to lie down flat without scrubbing, and increases lateral stability by distributing lateral forces lengthwise along the tread -- but is not applicable to narrow tires which must lean when cornering.
<div class="editbutton">
Abgerufen von „https://www.fahrradmonteur.de/Spezial:Mobiler_Unterschied/5159“

Navigationsmenü