![]() ![]() Wilson and Papodopoulos argue that mechanical trail may be a more important and informative variable, although both expressions describe very nearly the same thing. Trail is often cited as an important determinant of bicycle handling characteristics, and is sometimes listed in bicycle manufacturers' geometry data. Most bikes have positive trail, though a few, such as the two-mass-skate bicycle and the Python Lowracer, have negative trail. ![]() The measurement is considered positive if the front wheel ground contact point is behind (towards the rear of the bike) the steering axis intersection with the ground. Trail is the horizontal distance from where the front wheel touches the ground to where the steering axis intersects the ground. See also: Caster angle § Trail or trailing The length of a fork is measured parallel to the steer tube from the lower fork crown bearing to the axle center. Other, less-common motorcycle forks, such as trailing link or leading link forks, can implement offset by the length of link arms. In motorcycles with telescopic fork tubes, fork offset can be implemented by either an offset in the triple tree, adding a triple tree rake (usually measured in degrees from 0) to the fork tubes as they mount into the triple tree, or a combination of the two. The development of forks with curves is attributed to George Singer. The offset may be implemented by curving the forks, adding a perpendicular tab at their lower ends, offsetting the fork blade sockets of the fork crown ahead of the steerer, or by mounting the forks into the crown at an angle to the steer tube. Road racing bicycle forks have an offset of 40–50 mm (1.6–2.0 in). In bicycles, fork offset is also called fork rake. The fork offset is the perpendicular distance from the steering axis to the center of the front wheel. a 2007 Nevada Classic 750 with a rake of 27.5°.In motorcycles, the steering axis angle is measured from the vertical and called the caster angle, rake angle, or just rake a 0° rake is therefore vertical. Īt least one manufacturer, Cane Creek, offers an after-market threadless headset that enables changing the head angle. a 2006 Tete de Course, designed for road racing, with a head angle that varies from 71.25° to 74°, depending on frame size.ĭue to front fork suspension, modern mountain bikes-as opposed to road bikes-tend to have slacker head tube angles, generally around 70°, although they can be as low as 62° (depending on frame geometry setting).a 2007 Filmore, designed for the track, with a head angle that varies from 72.5° to 74° depending on frame size.In bicycles, the steering axis angle is measured from the horizontal and called the head angle a 90° head angle would be vertical. The steering axis angle usually matches the angle of the head tube. The steering axis is the axis about which the steering mechanism (fork, handlebars, front wheel, etc.) pivots. The steering axis angle is called caster angle when measured from vertical axis or head angle when measured from horizontal axis. Lankensperger, I rather glad we don’t call this system Lankensperger steering! The assumption was made that a carriage would rotate in a turn by a center somewhere along the line of the rear axle, that the outer front wheel had to turn faster and at a greater angle than inner front wheel and that the plane of front wheels would perpendicular to the radial axis to center of the turn.Example of a chopper with an unusually large rake angle In 1818, Rudolf Ackerman patented a design of Georg Lankensperger that provided a steering system for carriages that eliminated the angle scrub and subsequent wear of the wheels on the front axle. In order to do this I will start with a description of Ackerman steering which forms the basis for Anti-Ackermann steering. Let me qualitative describe anti-Ackermann steering. ![]()
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