Understeer and oversteer
As an example of understeer , imagine that you are driving a vehicle too fast through a curve and the vehicle “wants” to go straight even though you have turned the steering. The front tires lose traction ( static friction changes to sliding friction ) and no longer dictate the direction of travel . This behavior is often described in layman's terms with the phrase “The vehicle no longer steered”.
The opposite is the case with oversteer : The vehicle takes a tighter curve than it should actually describe after the steering wheel / tire position. Here the rear wheels lose their grip - or to put it colloquially : "The rear breaks out."
Vehicles with front-wheel drive are regularly attributed a tendency to understeer and vehicles with rear-wheel drive a tendency to oversteer. However, due to driving errors, oversteer can also occur with front-wheel drive, just as, conversely, understeer is also possible with rear-wheel drive.
Modern vehicles today are equipped with a vehicle dynamics control (ESC or ESP) in order to counteract this undesirable behavior.
Drift or Sliden ( English to slide for slide ) denotes a driving state, in which a vehicle in a curve moved laterally to its own longitudinal axis and therefore large skew angles are held on both axles. In a broader sense, the mere breaking away of the rear axle is often referred to as drift. A predominant rear wheel drift is also referred to in common parlance as oversteer . This means that after the rear of the vehicle has broken away, the steering has to be straightened or even steered towards the outside of the curve. A predominant front wheel drift is called understeer . This means that you have to steer more strongly than the curve radius would actually require.
The cam track on which the vehicle moves when oversteering is regulated by the throttle position. The driver only counter- steers to keep the vehicle stable. If he does not do this at a constant steering angle, but by moving the steering back and forth, it is called “sawing”.
A distinction is usually made between different drift techniques according to how they are introduced:
- Brake sharply with the front brake shortly before the curve to relieve the rear wheel. Engine speed to 2/3 of the max. Hold the speed and clutch at the grinding point. This is common with Supermoto.
- By accelerating in curves
- Through load changes: speedway, grass track, long track, rally. Vigorous releasing of the accelerator or downshifting when turning into a curve relieves the rear wheel, the result is oversteer. The degree of influence is determined by the engine braking torque and vehicle set-up.
- By rocking the vehicle: With the brake applied, i.e. with a slight rear end, you first steer violently away from the curve, then into the curve and then release the brake again. The result is that the vehicle pulls into the inside of the curve while the rear axle is still controllably sliding.
All drifts have in common that they can be lengthened in vehicles with rear-wheel drive through strong acceleration (the rear tires are overloaded by the drive forces and spin), this is referred to as a powerslide .
If the slide is too strong, your body weight should be shifted to the footrest on the outside of the curve and the knee on the inside of the curve should be gently pressed against the asphalt.
- With the handbrake: In front-wheel drive vehicles that regularly understeer, oversteer can be caused by briefly pulling the handbrake in a curve, causing the rear wheels to slip and causing the rear of the vehicle to break away due to a lack of lateral guidance. To use this technology in rallying, the handbrake was expediently designed as a hydraulic system without automatic locking. It is not enough to start the rotation with the handbrake; you have to be able to limit it again with the right counter-steering and accelerating. The use of the handbrake is often essential for tight turns at low speeds.
Drifting with cars has now grown into a separate motorsport category, especially in Japan and the USA (for example the D1 GP series), which is very popular with fans. Drifting is now finding more and more fans in Europe. See also: Drifting (motorsport) .
Classic cornering technology
In the classic cornering technique, the driver maintains an upright posture parallel to the central axis of the motorcycle in an inclined position. Therefore, he can support himself with both knees on the tank and has a stable connection to the motorcycle. This technology requires classic tire widths so that the tire contact point does not move so much outwards and, in connection with unevenness, leads to handlebar flutter (under gas up to tank slapper / handlebar slap ).
Push the motorcycle into the curve
With this cornering technique, which is used in motocross, enduro, super-moto or in emergency situations for quick evasive action, the driver pushes the machine under him into an inclined position while he remains sitting upright himself.
Lean into the curve ("hanging off")
When hanging off (Engl. To hang off , hang) refers to the sporty cornering technique in motorcycle road racing .
The driver hangs himself on the inside of the curve next to the motorcycle. Most of its weight is borne by the outside (upper) leg of the curve. He can hold the knee slider against the asphalt to control the lean angle, i. H. estimate the distance to the asphalt .
This technology shifts the entire system focus so that the motorcycle itself no longer has to be tilted as much, which would otherwise be necessary due to the strongly offset tire contact point. The reduced lean angle means that you can accelerate out of the curve earlier. In addition, the contact surface of the tires is larger when the lean angle is less (which does not apply to every tire, racing tires have a different contour), and footrests or other components do not touch the ground. In addition , the machine does not rock because the tire contact point that has moved outwards from the center of the machine does not only have to bear one-sided weight. This technology is practically challenged by the modern tire widths for super athletes.
Ride on the rear wheel
A wheelie is the driving of a multi-axle vehicle on the rear axle. When the front wheel is in the air, no unrest can be introduced into the chassis even on very uneven roads. When driving off-road with the two-wheeler, it may be necessary to lift the front wheel over obstacles.
Motorcycle acrobats can easily cover thousands of meters in this vehicle position.
Unicyclists generally ride on only one bike and sometimes travel around the world. Even foot - and stilt walkers , even more runners balance at times on a single point of support. Also, inline skaters balance and roll on unchecked wheels.
In the years around 2001-2018, single-axle electric vehicles (devices, Austrian StVO up to 2018: "vehicle-like children's toys") (two- and one-wheeled) Segway , balance boards and unicycles, which automatically balance on an axis with computer support and use weight shifting and exercising Torque along the vertical axis can be controlled by the driver.
On the one hand there is the so-called power wheelie, which is often seen in racing. When accelerating out of bends, the front wheel of the motorcycle often rises slightly. The front axle rises even when driving quickly over ridges. In races such as the MotoGP class with over 200 hp, full power cannot always be used, especially when accelerating out of corners. Even on the straight, only those who just keep the front wheel on the ground can accelerate optimally.
A gas wheelie is the setting up of the vehicle by suddenly opening the throttle grip. If the power is sufficient, the front wheel will lift off. At higher speeds , too little power or too low a center of gravity, the process can be made easier by tearing the handlebars. The suspension can also be used: if the throttle grip is suddenly closed, the machine springs forward; if it rocks back again, you open the twist grip and the front wheel goes up. With light machines, this is even possible without releasing the accelerator with just your body weight and a little tearing on the handlebars.
There are two ways to prevent tipping backwards: With four-stroke engines, the engine braking is often sufficient and the front wheel is lowered by slightly throttling the gas supply. The much safer technique, however, is to use the rear brake to stabilize the wheelie angle. If you want to drive a longer distance at the tipping point, you have to carefully combine the rear brake and the accelerator.
With the clutch wheelie, you disengage the clutch , increase the speed and then engage again very quickly. With weak, heavy, long or low-lying motorcycles such as choppers or heavy tourers, this can also occur when starting off, for example with a pillion passenger and luggage. Mostly, however, due to the design, instead of wheelie, the rear wheel spins ( burnout ), which can also be caused willfully by the driver. The cavalier start is also called the traffic light start. Due to the loss of static friction between the tire and the asphalt, tires often squeal when starting or rubber abrasion on the road.
The center of gravity of the vehicle is of crucial importance for wheeling: the lower it is, the more force is required for a wheelie. With various models such as choppers or heavy tourers, this simply means that they do not go on the rear wheel without having been technically modified. If the required power can no longer be transmitted through the drive tire, the rear tire will spin (burn-out). If the wheelie is to be prevented structurally, a wheelie bar is installed .
Ride on the front wheel
Under Endo understand motorcyclists putting up the motorcycle on the front wheel.
This is achieved through the dynamic wheel load distribution when braking hard with the front brake. It is important that you do not brake immediately with full force, but that the pressure on the brake is continuously increased - otherwise the front wheel will slip and lock.
A distinction is made between two stoppies :
Stop on the front wheel
The standing stoppie, which occurs immediately before the motorcycle stops or when the motorcycle is already stationary.
Ride on the front wheel
The rolling stoppie, where you ride on the front wheel.
Upon burn-out ( burning out ) lets the driver by turning the wheels of one axis (for solid brake for the other axis). This is mainly used for dragster races ( acceleration races ); as the tires spin, they heat up, which ensures better grip on the track. Furthermore, burnouts are often shown as a show insert at car meetings, stunt shows and races.
Burn-out is not prohibited on public roads in Germany, only the noise and smell that is often associated with it. Burn-out not only consumes a lot of fuel, but the entire drive train of a vehicle is subject to enormous stress: The tires wear out very quickly and are usually unusable after a burn-out. Gearboxes and drive shafts as well as all torsion-loaded components (in particular Hardy disks, clutches) experience considerable wear, and failure of individual or entire assemblies cannot be ruled out. During a burn-out, however, not only is the drive train put to the test (similar to the stress of a bang-out start ), the engine must also withstand this stress (usually high speeds and the associated high temperatures without adequate cooling).
In Switzerland, burnouts can be reported if you do not control the vehicle .
With standing burn-out, the drive wheel or wheels spin while standing ( standing burn-out ).
If the rear wheel or wheels spin while driving, this is known as rolling burn-out ( wheelspin ).
The spinning and thus freely controllable rear wheels make it possible to paint lines or circles (donuts) on the asphalt through the rubber abrasion.