We've seen it many times before: it starts to rain on the track, the white flag is raised, and the riders head to the pit lane to change their bike. As we know, each rider has two bikes for the race. If rain has been forecast it's likely that the second bike is set up for these conditions. How is the setup different for dry and wet conditions?
The Repsol Honda Team mechanics can make the changes necessary to adapt the motorbike to wet or dry conditions in just 3 – 5 minutes. They works simultaneously on different parts of the bike to save time, as mother nature might have an unexpected surprise in store.
The most important element to take into account are obviously the tyres. Slicks are used in normal conditions in MotoGP, but these are changed for wet tyres that offer better grip if it rains. Taking advantage of the fact that the rims are off the motorbike, the break disks are also changed if the team considers it necessary. Steel brakes have been traditionally preferred over carbon ones when it rains. However the latter are increasingly used in all conditions, along with a cover that keeps the discs within an acceptable temperature range. The brake pads always need to be changed for ones that are more suited to wet conditions. If the team ultimately decided to install steel discs, the whole system would need to be changed, including the calipers and the pads, and the hydraulic system would have to be drained.
The suspension setup may also be changed depending on whether the race is taking place on a wet or dry track. Softer springs are used on the front wheel, which can be installed on the upper part of the fork. Any changes to suspension on the back wheel are a bit more complicated seeing as the entire system needs to be removed, but a well-prepared team can change it with another system that is already entirely set up.
If we use softer springs, the weight will be better transferred to the front of the motorbike, increasing the temperature and traction of the front section. This means we must also change the compression and extension of the shock absorber. This is a very delicate process as an incorrect setup could impact the bike's back section. Here, the key is to find an elusive balance, which is even more difficult in the changing conditions of a wet track.
While the mechanics are working flat out, the team's electronic engineer changes the bike's control systems in the ECU. The programs will work differently in wet and dry conditions, being more conservative when the track is wet and making for smoother riding.
Lastly comes a simple and small step that we mustn't forget: taking the caps off the the lower part of the fairing. These caps prevent any spills in case of a failure, but they would fill up with water in the rain! To avoid this, the motorbikes have draining caps.
Once the bike is ready, the rider can enter the pit box to make the change, get onto their new motorbike that is perfectly adapted to the new conditions, put their foot down, and get back on the track.