Rear wing flexing: graphic explanation of new F1 tests expected in China. The goal of the new deformation tests expected in China differs from those of previous years.

Technical checks are changing starting from the Chinese Grand Prix, with stricter deformation criteria for the rear wing. In recent months, the FIA has worked intensively to curb the flexing of aerodynamic components, tightening regulations for both the front wing and the beam wing. The new rear wing tests focus on a different approach than what has been addressed in the past, requiring a procedure tailored for this purpose.

The opening race in Melbourne certainly helped the Federation build a clearer picture of what was happening. The numerous straights at the Albert Park circuit provided enough data on the deformation of wing profiles at high speeds, monitored through onboard cameras and optical references applied to the wings. In recent years, much attention has been given to the front wings, while less focus has been placed on the rear wings, even though their flexing has been controversial in the past. For example, the 2021 World Championship battle forced the Federation to tighten tests, but at that time the aim was to counter the collapse of the entire rear wing structure.

This time, the focus is on the flexing of the main profile of the rear wing, monitoring its distance from the upper movable flap, the same one that opens when the DRS is activated. McLaren was the first to inadvertently draw attention to this area in 2024, with its low-downforce wing used at the last Grand Prix in Baku. The wing featured a mobile profile whose ends lifted at high speeds. In effect, this was a partial opening of the gap between the two wing profiles, commonly referred to as the mini-DRS effect. However, the test expected this week in China suggests that the new team practice differs. The opening of the ‘mini-DRS’ would not be caused by the lifting of the upper flap, but by the lowering of the main profile.

How the test changes
The FIA had already added a new flexibility test to the first version of the 2025 technical regulations, requiring the application of two equivalent loads of 75 kg each. Both forces are directed downward and are applied to both sides of the main profile. According to the criteria in place in Australia, the distance between the lower profile and the upper movable profile could not vary by more than 2 millimeters. Starting from China, however, the allowed variation will decrease to half a millimeter, with a 0.25-millimeter tolerance for short notice, which will then disappear at the subsequent race in Japan.

The Federation informed the teams on Monday, March 17, with less than four days to adjust before the technical checks scheduled for Thursday in Shanghai. For the teams, it is a race against time, and some quick, possibly makeshift methods are expected to be used to respond rapidly. It is difficult to quantify the effects on track, but in a Formula 1 where 16 drivers were within 7 tenths in Q1 in Australia, even the slightest impact on the clock can make a significant difference in terms of results.