FIA Closes the Floor Stay Loophole: Red Bull and Audi Must Redesign Their Sidepod Undercuts for 2027

On the RB22 at the 2026 Austrian Grand Prix there was a detail the naked eye struggled to catch: a structural cable running down the lower ridge of the sidepod, where only a smooth aerodynamic surface should have been. Craig Scarborough — the technical analyst I have followed for many seasons — pointed out that Red Bull had exploited a tiny carve-out in the wording of the regulations governing the “floor body stay.” The rulebook permits bodywork sitting near that stay to be rounded with a radius of 20mm. Just twenty millimetres. And those twenty millimetres allowed the technical department in Milton Keynes to mould an undercut far sharper than any rival running standard bodywork.

A few rounds later, in Baku, Audi copied it almost verbatim.

Then the FIA stepped in. According to a scoop from Rosario Giuliana at AutoRacer.it, the governing body is amending the 2027 technical regulations to reduce the permitted radius of the floor body stay from 20mm to 5mm. Those fifteen millimetres being cut away amount to a quiet prohibition: the configuration disappears, and both Red Bull and Audi are forced to redesign the entire lower section of their sidepods.

The floor stay: a safety tolerance that became a doorway

To understand why fifteen millimetres is worth an article, you have to picture what a floor stay is. It is a structural component that holds the floor bodywork, carries load and keeps the floor from oscillating at high speed. Because it is a load-bearing part, the rulemakers allow the bodywork surrounding it to be rounded a little — 20mm — to avoid creating a sharp edge. The original intent was purely structural and safety-driven.

But in a sport where every millimetre of geometry is weighed in the wind tunnel, a structural tolerance becomes a doorway. Red Bull did nothing wrong. They simply read the rule more closely.

The FIA chose to amend the 2027 regulations rather than issue an immediate technical directive. That approach leaves the current season undisturbed, but it also shows the governing body understands this is a wording loophole, not cheating. History has repeated itself several times: Brawn GP's double diffuser in 2026, Mercedes' DAS in 2026, then the flexible wings tightened by technical directive in 2026. The cycle is always the same — a team finds a gap, the paddock copies it, and the rule is patched.

I began following Formula 1 in 2026 and have not missed a Grand Prix since. Based on my experience covering races across more than three decades, this cycle has never changed shape, only speed. It once took half a season for a design to spread across the paddock. Now it takes a few rounds.

The geometry of an undercut

Every race is a network; I only look for the choke point. This time the choke point is not on the track. It sits inside a sentence of the technical regulations.

Picture a cross-section of the sidepod. Its lowest section tapers inward — that is the undercut, the path that guides airflow along the flank and down into the floor edge. The floor is where most of the downforce is generated in the ground-effect era. The stronger and cleaner the airflow into the floor edge, the larger the low-pressure zone beneath, and the more grip the car has.

In a standard design, the undercut is a large-radius arc — soft, gentle, with the airflow separating early. With a 20mm tolerance, Red Bull turned that arc into a wedge. A smaller radius means the lower edge of the sidepod is sharper, and the airflow is pressed against the flank for longer before being released down to the floor. Fifteen millimetres of difference on paper is trivial. At the geometric scale of a Formula 1 car, it changes the gradient of an entire surface tens of centimetres wide.

The whole technical rulebook is a spider's web. The diagram does not lie, but the people reading it do. From the same regulatory drawing, ten teams read ten different interpretations, and only one thought to run a structural cable down the lower ridge of the sidepod to justify that shape.

The trade-off deserves clarity. This is a design change, not a new component, so it barely touches the cost cap. But time is a scarcer resource than money. Every week an engineer has to return to the sidepod floor drawing is a week not spent on another development direction. For Audi — a new team building its structure from scratch — that price is far heavier than for a team with an established baseline.

Audi copying the solution just a few rounds after the RB22 appeared in Austria reveals something about the whole network: the gap between inventor and imitator is now measured in weeks, not months. In the wind tunnel, every secret has a very short shelf life.

The contrarian angle: we are trusting an unverified diagram

The place I want to pause is here. Nobody in this story offers a single performance number. There is no lap-time data, no downforce comparison, nothing proving that a sharper undercut actually delivers an advantage on track. All we have is a geometric analysis and a regulator's response.

Physically, a sharper undercut does not automatically mean a faster car. Forcing more air into the floor edge can unbalance the rear pressure field, making the rear unstable in low-speed corners. An advantage in one place can be paid for in another. Data is a shelter, but story is home — and this story is told by Motorsport Bulls Watch, a newsletter for Red Bull fans. The labels “cheeky” and “clever” reflect the teller's vantage point, not the track's. I still want to cross-reference Scarborough's original analysis and the AutoRacer.it source before believing those fifteen millimetres ever made a real difference.

But one thing I believe more firmly. Red Bull's real advantage is not those twenty millimetres. It is the ability to read wording. A group of people who read regulations down to the last comma is an asset that cannot be patched by a single rule change. The FIA can close this loophole, but it cannot close the capability that created it.

And ask the reverse: if the FIA did nothing, what would happen? By mid-2027 every team would have copied it and the advantage would evaporate on its own. The rule change merely accelerates an unavoidable outcome.

On the tactical map, emotion is the coordinate people forget to plot. For Red Bull fans, this is a governing body punishing creativity. For rival teams, it is technical justice arriving late. Both emotions are real, and no dataset reconciles them.

What to watch

The next race I am waiting for is not a Grand Prix, but 2027 pre-season testing. When the new cars roll out, we will see what the sidepod floors of Red Bull and Audi look like, and whether Red Bull's aerodynamic department can find its next trick before the season begins. History gives them until spring.

Audi faces a harder question: learning to think for itself instead of waiting to copy. And the FIA has a recurring lesson: every time it plugs one hole, it teaches the whole paddock exactly where to read more carefully next time.