Many aspects affect the choice of suspension used by GP teams: track conditions, tires used, driver feedback and technical calculations. Although the suspension may seem simple at first glance, it is actually particularly complex. The front fork alone is made up of more than 300 parts.
The four most important terms for suspension are: springs, preload, compression and rebound. A perfect balance is necessary between all these concepts and elements so that the motorcycle behaves as we want, adapting to the needs of the rider.
Departments
Springs are components that support the suspended weight of the assembly. They need a certain force to be compressed which depends on its rigidity. So, the selection of a specific spring will depend on the rider's needs for each track. Springs are classified according to the force required to compress them.
Stiffer springs provide better support when braking and compress more slowly. The trade-off is that they make the motorcycle more critical during leaning and tire wear is higher.
Suspension elements ready to be used
On the other hand, softer springs offer lower stability during braking and the spring can reach full compression under hard braking with the dangers that this entails. However, the bike will be easier to control on the angle and they will generally be preferred when it is raining on the circuit.
To perform spring adjustment, simply open the front fork caps to remove the component and insert another. The operation takes less than two minutes and allows the insertion of springs of different stiffness into each tube to obtain a more precise adjustment. In the case of the rear shock, the process is a little longer and it is usually necessary to have a complete module ready for installation.
Oil level and viscosity
Reducing the oil level slightly allows the fork to compress more easily and the rider will feel a smoother, smoother fork. Increasing it will have the opposite effect, because the higher the oil level, the higher the resistance. The viscosity of the oil will also cause the fork to react differently: with a higher viscosity index, it becomes more difficult to depress the fork throughout its travel.
Preload
We call preload the compression exerted on the spring while the assembly is at rest. In other words, it is compressed slightly to prevent it from reaching full extension. By increasing the preload, the system will require more force to compress, as such the suspension will take longer to fully sink. You can also vary the preload to change the height of the vehicle by changing the distance traveled by the shock absorber.
A KTM from the Tech3 team in the box – the technicians take the opportunity to adjust the suspensions
The preload adjustment varies between certain limits, like any other element, so, to avoid reaching them, it is better to change the springs for stiffer or softer springs and aim for greater precision.
During the race weekend we can see technicians making this adjustment in the box, using wrenches in the upper part of the fork and turning one way or another depending on whether they want to increase or decrease the preload.
Compression and relaxation
Once we have chosen the springs that suit us and the preload adjusted to our needs, we can make the compression and rebound adjustments. The suspension reacts by compressing when the trail is bumpy, for the fork when braking or for the rear shock when accelerating. Once the suspension is compressed, the spring will always tend to return to its original position beginning the rebound process. Depending on the adjustment we use, the extension will be faster or slower.
Finding an effective compromise remains complex with all the adjustment possibilities
The shock absorber has internal fluid that passes through certain valves as the assembly compresses. By means of these valves we can determine the adjustment of compression and expansion, if we close them somewhat the fluid will pass more slowly, thus slowing down the process. If we open them we get the opposite result. The adjustment is so precise that different speeds can be established for compression and extension.
The appropriate speed should allow the tire to be in constant contact with the ground, maximizing the motorcycle's grip. It also impacts acceleration and braking.
Even the aerodynamics of the forks are being studied
Ducati used this fork cover towards the end of last year and it was also seen during testing in Qatar this year.
The idea behind this is to reduce turbulence by smoothing the air around the front fork. The goal is to supply air to the radiator as efficiently as possible, and thus maintain the engine temperature within the optimal range!
