Reigning world champion Max Verstappen appears to have reverted to the more conventional rear wing for Saturday while Mercedes has abandoned its heavily-modified floor for the rest of the weekend at Spa. F1Technical's lead journalist Balazs Szabo delivers his latest analysis.

While championship runaway leader Max Verstappen ran a "conventional" rear wing assembly, the Dutchman tried out an even skinnier configuration with in Free Practice 2.

This second, "extreme" version has an identical main plane to the more loaded configuration that was used by Sergio Perez in both practice sessions on Friday. Their flaps are also similar with both featuring the same rectangular, upward swept tip section.

However, the key difference is the upper edge of the flaps with the second assembly featuring two prominent, widely stretched convex cut-outs on both sides of the flap while it also retains the V-shaped cut-out in its middle section.

It was believed that Red Bull might chase an extremely low-downforce configuration for Max Verstappen, who will serve a ten-place grid penalty for exceeding his power unit allocation.

However, the Dutchman reverted to the more loaded rear wing for Free Practice 3 which could be associated with two reason. First, Verstappen felt less comfortable in his RB20 in the second practice with the extreme rear wing with both McLaren drivers managing to beat him. Secondly, the wet weather that is dominated Saturday could have also motivated Red Bull to revert to the more loaded wing to generate more downforce on the wet, slippery surface.

Mercedes ditches heavily-upgraded floor

For this weekend's Belgian Grand Prix, Mercedes brought a total of five upgrades. The most visible update revolves around the floor that has gone through key changes compared to the previous version.

The floor edge has been heavily revised as it now features an additional flap element over the forward section of the edge. The new element “drops the local pressure behind the fence system which in turn increases forward floor load.”

The expansion of the floor that is referred to as diffusor has also been altered, albeit the team called these changes “subtle”. The roof section now features an increased camber compared to the previous assembly which should “increase local flow acceleration which in turn increases local downforce and drag.”

All these changes indicated that Mercedes had been confident that generating more downforce with the floor would not induce bouncing that hindered the car’s behaviour when the sport switched to the ground-effect cars.

However, as Lewis Hamilton and George Russell headed out on to the Circuit de Spa-Francorchamps this morning, it emerged that their W15 was equipped with the older-spec floor. The seven-time world champion complained over the radio that his car was bouncing in practice.

While the team could have mitigated the bouncing by running the car higher, Mercedes might have thought that it would be easier to revert to the older floor that has worked well in recent rounds. The team will perform a thorough analysis after the Spa weekend to figure out how they need to alter the new floor or tweak the setup to solve the unintended side-effect for the future races.