F1 Tech | How Baku highlighted the SF-25's still narrow working window

11:34, 25 Sep

byFrancesco Bianchi

The weekend in Baku was quite a disappointing one for Ferrari, as the team struggled in qualifying, eventually compromising the race as well, with Hamilton and Leclerc finishing only in P8 and P9, respectively. The weekend showed some of the big limits in the SF-25, including the tyre warm-up struggles and the poor mechanical grip generated by the suspension system. Let’s try to deep dive into these problems.

Lewis Hamilton during the Azerbaijan GP | Photo: Race Pictures

The Scuderia arrived in Baku with a clear goal for the weekend: to show a good level of performance and potentially fight McLaren and Red Bull Racing for the victory. As a consequence, since FP1, they made a lot of comparison runs between Hamilton and Leclerc to test different rear wing and beam wing solutions, to gather data on which version best suited the Baku City Circuit layout.

In FP1, Hamilton and Leclerc used two different rear wing and beam wing solutions: as highlighted in the drawing below, Hamilton tested a high downforce rear wing, characterised by a spoon mainplane, which has a curved leading edge to maximise the downforce generated across the whole profile. The DRS flap has a relatively long chord, but shows off a slightly trimmed trailing edge and an oval cut in the central portion (yellow arrow).

This cut, in fact, serves to reduce the surface area exposed to the air and, consequently, to reduce the drag produced by the airfoil itself. Above all, it also reduces the turbulence generated by the DRS support, favouring the interaction between the high and low pressure areas, maximising the efficiency of the flap. For what concerns the beam wing used by the Briton, it was the same low downforce spec already used in Monza, characterised by a very short chord to minimise drag.

On the other side, Leclerc used a much more unloaded rear wing matched with a slightly higher downforce beam wing: the rear wing spec was the same one used by Hamilton, but the DRS flap featured a much more trimmed trailing edge, mainly to reduce drag (yellow arrow). This solution inevitably produced way less downforce on the rear axle and, to slightly compensate, the team used a drop-shaped beam wing, which has a long chord at the connection to the rear impact structure and a shorter chord as it gets closer to the endplate (green arrow). This overall solution, however, generated less downforce than the one used by Hamilton, and also suited Leclerc’s driving style, as he usually prefers a car that’s more ‘on the nose’.

SF-25's rear wing and beam wing comparison between Hamilton and Leclerc in Baku

This wasn’t the only change the team made to adapt the car to the stop-and-go nature of the track: as shown in the drawing below, the top flap of the front wing was specifically trimmed in different portions to guarantee the best balance between efficiency and downforce generated.

The orange arrows, in fact, show how, compared to the maximum-load version used in the Netherlands, the last flap has been cut right next to the flap height adjuster, to maximise the outwash effect at high speeds, reducing the mass of air hitting the front wheel. At the same time, at the connection to the internal metal support, the flap chord has been trimmed (pink arrow) compared to the version used in Zandvoort, to further maximise the efficiency of the profile.

SF-25's front wing spec Baku vs. Zandvoort

All these technical choices made the SF-25 quite balanced during the first session, showing a very good level of performance, especially on the straights and in some of the slow-speed corners in the second sector, despite the dirty track and the conditions far from ideal, especially from the wind point of view. However, the car was still struggling a lot in terms of tyre warm-up, losing a lot of time in the first sector compared to McLaren, proof that the front tyres were still not ready in the first part of the lap.

The team also took advantage of the long red flag halfway through the session to change the rear wing on Hamilton’s car and switch to the lower downforce spec used by Leclerc as well. In the final minutes of the session, however, the Britain never seemed to find the right feeling, both with this set-up and with the brakes, as he was unable to set a competitive time and finished the session only in P13, with Leclerc up to third.

For FP2, the team mainly worked on fine-tuning the set-up and giving more confidence to their drivers: Hamilton’s car was fitted with the higher downforce rear wing he tested in the morning, and additional changes were made to the front brakes, in order to give him a more stable car under braking, a fundamental aspect to gain time on such a difficult circuit. On Leclerc’s side, he kept using the same set-up of the morning, proof a good level of confidence.

Leclerc during FP2 in Baku | Photo: Race Pictures

The results seemed promising: Hamilton and Leclerc topped the second session, almost half a second faster than Russell in P3, while the McLaren drivers didn’t complete a clean lap on the soft rubber. The SF-25 behaved way better under braking than in FP1, allowing Hamilton to push more from that point of view, as he also performed quite well in the race pace simulations, despite completing only 3 laps.

After the session, interviewed by Sky Sport F1, Vasseur commented on the set-up tests done in the two sessions as follows: "On high-load circuits, you know the setup perfectly. When exploring at low load, we have to correct the data, and we did a cross-test to understand which setup is best, and then we'll make a decision this evening.”

Hamilton, instead, felt quite positive about the confidence with the brakes: “We made some changes for FP2, and finally the brakes were working perfectly, and I was able to really make a lot of gains in braking. I'm very happy to see the progress, and it shows the direction we're taking as a team.”

A difficult qualifying due to warm-up issues

After such a positive Friday, the team fitted the same set-up on both cars, the same set-up used by Leclerc on Friday, hoping that the track evolution and the additional grip exploited by the soft tyre would help the drivers in qualifying, allowing them to fight for pole. As shown in the drawing below, however, Hamilton and Leclerc still kept small differences in their set-ups: the Britain chose the drop-shaped beam wing (pink arrow, right-hand side), which provided slightly more downforce on the rear axle, making the car more stable and balanced under braking and traction, which is exactly where Lewis was struggling more than Charles during the first half of the season. Leclerc, instead, used the lower downforce beam wing used in Monza, to maximise the top speed on the straights (pink arrow, left-hand side).

Moreover, the team also adopted the typical asymmetrical cooling louvres on the car, with one big exit on the right-hand side and two additional smaller fins on the left-hand side (light blue arrow), conscious of the temperature drop expected for the remainder of the weekend.

SF-25's beam wing comparison used in the Azerbaijan GP

Despite these changes before qualifying, the performance expressed on Saturday was less than optimal for the team: due to the cool temperatures and the very low level of grip provided by the asphalt, both drivers massively struggled in warming up the medium tyres, with Leclerc ending up in the wall at turn 15 in Q3 and Hamilton out of Q2. The Monegasque commented on his result as follows: “All the laps on the soft felt much better. Then we went on medium, which we had kept because we thought it was the best tyre and today with these temperatures it was just impossible for me to switch them on.”

The very disastrous performance in qualifying highlighted some big weaknesses of the SF-25:

The lack of mechanical grip, which appeared quite evident already during FP3, but was masked by the additional grip provided by the soft tyre. Despite the changes on both the front and rear suspension, the SF-25 still struggles a lot compared to McLaren and Red Bull in slow-speed corners and in tyre warm-up, as heat is generated by the friction between the tyre and the road.
The still very narrow working window: despite the very good performance on Friday, as soon as the conditions became cooler on Saturday and the track provided less grip due to the rain that fell during the night, the SF-25 massively struggled in warming up the tyres, losing tons of performance as a consequence.
The lack of a particular ‘strength’: compared to 2024, when the SF-24 was very strong in slow speed corners and tyre management, the SF-25 doesn’t have a particular strength, nor in corners or straights. This means that the car does not have a 'favourite' circuit, but rather expresses a mediocre performance on almost all layouts, making it harder for drivers to fight for poles and wins.

These limitations compromised the qualifying result, which, as a consequence, enormously affected the race on Sunday: due to the very cold temperatures, the tyre wear almost disappeared, preventing Ferrari from having an advantage in terms of tyre management over the midfield cars ahead of them, such as Williams or Racing Bulls. Moreover, the very low downforce rear wings adopted around this track made it very difficult to overtake if you’re stuck in a DRS train. That’s exactly what happened to Leclerc and Hamilton, who found themselves blocked behind Lawson in P5, unable to progress.

This aspect was underlined by Team Principal Fredric Vasseur as well after the race: “Baku is not the easiest place to attack, because when you have the small wings, the DRS effect is much smaller and so on.”

The result of all these factors was a disastrous weekend for Ferrari, who scored only 6 points on Sunday, compared to the 11 of Racing Bulls, 15 of Williams and 30 of Mercedes that also overtook the Scuderia for the 2nd place in the Constructors’ Championship. For them, it’ll be particularly important to progress in the remaining 7 races of the season, to take back the second position in the standings, which, however, should not act as bait to save the disappointing 2025 season.