Lewis Hamilton was clearly in pain as he parked his Mercedes F1 car after the Azerbaijan Grand Prix and gingerly lifted himself out. For the past 95 minutes, his body had taken a beating within the cockpit, with his back subjected to the full brunt of the car smashing into the track around Baku's bumpy streets.
At more than 200 mph, the car was bouncing so hard on its suspension that Hamilton could barely spot his braking point for the first corner. Later in the lap, as he rounded Turns 18 and 19 at 180 mph, he had to second guess the movement of the car underneath him as it bottomed out and skated across the track surface.
A Mercedes engineer later revealed the compressions from the bouncing were registering at 6G (six times the force of gravity) through the car. As an isolated impact it wouldn't be an issue -- drivers regularly pull longitudinal forces of 5G under braking -- but Hamilton was experiencing 6G in vertical loads at an extremely high frequency as he went down the pit straight on every lap during a 51-lap race.
"There were a lot of moments where I didn't know if I was going to make it [to the end of the race]," Hamilton said. "One, whether I was going to keep the car on track, as on the high speed I nearly lost it several times. The battle with the car was intense.
"The thing was bouncing so much there were so many times I was nearly going into the wall, that was a concern safety wise, 180mph smashing into the wall. I don't think I've ever really had to think about that as a racing driver, keeping it out of the wall at that high speed, very strange experience.
"That was the most painful race I've experienced, the toughest race I've experienced."
The grand prix left Hamilton with bruising on his back, although he reassured followers on his social media the next day that it was "a little sore ... but nothing serious." He's now preparing for more of the same at this weekend's Canadian Grand Prix.
Hamilton wasn't alone in experiencing the bouncing in Baku, but he seemed to suffer more than any other driver. As a result of changes to the regulations over the winter that have made the latest generation of F1 cars stiffer and more susceptible to an aerodynamic phenomenon known as porpoising, every driver has experienced some level of bouncing in the cockpit this season.
Ferrari's Carlos Sainz was the first driver to publicly suggest something should be done about the issue, raising concerns about the long-term health impacts of the bouncing over the next four years.
"We need to consider how much of a toll a driver should be paying for his back and his health in a Formula One career," the Ferrari driver said in May. "With this kind of car's philosophy we need to open a debate more than anything."
In Baku, Mercedes driver George Russell, who is also the president of the Grand Prix Drivers Association (GPDA), suggested the FIA should consider a rethink of the rules to combat the worst of the issues.
"It is just unnecessary with the technology we have in today's environment, it just seems unnecessary that we are running a Formula One car at over 200 mph millimetres from the ground and it's a recipe for disaster," Russell said. "I don't really know what the future holds but I don't think we can sustain this for three years or however long these regulations are in force for."
Regulatory change this season seems very unlikely, especially as teams can ease the bouncing by running higher ride heights and different suspension settings. But with the current regulations set to remain in place until 2026, there are concerns about letting teams sacrifice driver health in the pursuit of performance.
Why was the bouncing so bad in Baku?
It should be said that not all teams had issues. Red Bull, which took a one-two victory in Baku, looked like it had a much more stable platform than its rivals and analysis by Sky Sport's Karun Chandhok showed how easily the Red Bull rode the bumps in corners compared to Mercedes, while, to the naked eye, appearing to run a higher ride height.
So, at the most extreme end of the bouncing spectrum, what is going wrong for Mercedes?
After struggling with porpoising at the first five rounds of the year, Mercedes was hopeful it had found a solution with an upgrade at the Spanish Grand Prix. At that race the porpoising was greatly reduced, especially on the pit straight, meaning the team could start to run the car closer to its intended ride height and extract more performance from the underfloor aerodynamics, which are so crucial to lap time under F1's new regulations this year.
While the team enjoyed performance gains on the smooth track surface at the Circuit de Catalunya, running the car low to the ground threw up new challenges at the next round in Monaco. Over the bumpy streets of F1's oldest street circuit, the car's floor regularly bottomed out on the track surface, making for an uncomfortable ride for the drivers and difficulties maintaining the tyre's contact patch with the asphalt.
Again, an easy solution to the ride issues would be to raise the ride height and soften the suspension but that would have a direct impact on the aerodynamic performance of the car -- to the point that Mercedes believes it would drop down the order. Running a low ride height accelerates the airflow under the car, creating low pressure that sucks it to the track. In theory, the lower you run the car the more downforce it creates, although as we've seen this year, it also increases the risk of exposing any flaws in the underfloor aerodynamics.
The problem at the start of the year for a number of teams was that the immense levels of downforce being generated by the underside of the car was creating so much downward pressure that the car's floor would start to flex and bottom out. That had the potential to stall the airflow underneath the car, resulting in a momentary loss in downforce that resulted in the car rising back up on its suspension until the airflow underneath started doing its job again, sucking it back down. Repeated over and over again, the upwards and downwards motion would continue until the driver hit the brakes for the next corner. This is known in F1 as porpoising.
Once Mercedes made progress with solving its porpoising issues in Spain, it could suddenly run its car at lower ride heights without inducing the bouncing, leading to more cornering performance. All well and good, but when it came to racing at Monaco the lower ride height meant the car was simply slamming into the track surface over bumps, making for an uncomfortable ride that exposed a whole new layer of issues.
Like Monaco, Baku has a bumpy track surface but on top of that it also has several high-speed sections. It was in these high-speed parts of the track where the bottoming out was at its worst and triggered a bouncing motion that, from the outside, looked similar to the porpoising earlier in the year. However, unlike the issues prior to Spain, Mercedes does not believe the bouncing in Baku had an aerodynamic trigger and was instead related to the car's ride over the bumps.
The big problem Mercedes faced in Baku, which ultimately led to Hamilton's visible pain, was that there was a direct correlation between improved performance and driver discomfort. The lower the car runs, the more downforce it generates and the faster the lap times, but in doing so the driver is exposed to more of a beating in the cockpit. Ask an F1 driver if they are willing to experience discomfort in exchange for performance and there will almost always be one answer -- no matter how savage the implications are.
What's more, the uncovering of new issues in Baku meant the team was running extreme setup experiments with both cars in an effort to find solutions, adding to driver discomfort. To be fair to Mercedes' engineers, they will never be able to get rid of the issues if they can't push the limit to understand them, and so, if Hamilton and Russell want to return to the front of the grid, they will both have to take some pain along the way.
"I think we know what the root cause of our problem is, but we don't have the answers yet of what the best solution will be," Mercedes team boss Toto Wolff said. "And this is what we are experimenting with at the moment.
"I still think there is a short-term fix which is making us much more competitive, but it might not explain everything. I'd like to get the car in the right position for the second half of the year and also for next year."
The two drivers ran slightly different setups in Sunday's race, but the ride height was the same across both cars. Hamilton's setup was more of a deviation from the team's original plan and resulted in a harsher ride, although in terms of driver discomfort it should also be noted that Hamilton is 13 years older than Russell and may be feeling the continued strain on his back more than his younger teammate.
"Honestly, George didn't have the same bounce I had, he had a lot less bouncing, yesterday I lost 3.5 tenths to him on the straights," Hamilton said after the race. "I had an experimental part on my car, and the different rear suspension. Ultimately it is the wrong one."
Mercedes is confident that when it returns to a smooth track surface (the next one will be Silverstone for the British Grand Prix in July) it will help the bouncing, but that won't mean the Baku issues have gone away. In order to engineer a way out of the problems, Mercedes will need to continue to experiment and that could mean more driver discomfort.
What will happen next?
Some of the drivers raised their concerns about the ride of this year's cars at the FIA driver's briefing in Baku, but it's clear not all drivers or teams consider it a safety concern. In order for the rules to change either during this season or for the start of next season, at least eight teams would need to agree along with F1 and the FIA that something should be done. That seems unlikely given that several teams have either solved or successfully managed their bouncing and are gaining a competitive advantage as a result.
Red Bull, which leads the drivers' and the constructors' championship, has no incentive to agree to a rule change that could have a negative impact on its own advantage over the rest of the field. After Sunday's race, team boss Christian Horner said it was up to the teams struggling with the issues to find a solution or implement the known fix of rising their ride height if the situation is considered dangerous.
"I mean, look, you can see it's uncomfortable, but there are remedies to that," he said. "It's to the detriment of the car performance. What's the easiest thing to do is to complain from a safety point of view, but each team has a choice.
"I think if it was a genuine safety concern across the whole grid, then it's something that should be looked at. But if it's only affecting isolated people or teams then that's something that that team should potentially deal with."
The FIA could make unilateral changes to the regulations on safety grounds, but the counter argument is that the onus is on the teams to run their cars in a safe manner and there is clearly the potential to do that without a regulation change.
It seems, therefore, that the bouncing problems are here to stay until the teams suffering the most get on top of them. On smoother track surfaces it will likely be less of an issue, however, and the run of purpose-built race tracks after this weekend's race in Montreal of Silverstone, the Red Bull Ring, Paul Ricard, Hungaroring, Spa-Francorchamps, Zandvoort and Monza may be enough to ease drivers concerns over the coming months.