F1 2021 rule changes: what teams aren’t showing us on their new cars

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Stability in uncertain times: that was the idea behind the 2021 Formula 1 season following the havoc wreaked last year by Covid.

But despite pushing the large-scale car design regulation changes back to 2022, there are plenty of changes that could alter the running order this year.

Bringing the creative minds of F1 designers to a standstill isn’t possible, so measures have been introduced to cut downforce by 10 per cent and curb the ever-increasing speed of the cars.  The series’ first cost cap has been brought in, along with tokens that restrict development and rules that reduce the ability of teams to copy rival designs.

It all added up to a busy winter for designers and the potential for teams to steal a march on rivals. Which is why all of the 2021 cars launched so far are expected to look significantly different when they line up in Bahrain for the first race of the year.

One feature that can’t be disguised is the reduced floor area required this year to cut the downforce it can generate.

Rule makers decided that change couldn’t wait another season, given the increasing stress being placed on the Pirelli tyres from higher cornering speeds. This was violently demonstrated at the 2020 British Grand Prix, when Carlos Sainz, Valtteri Bottas, and most notoriously Lewis Hamilton, all suffered major tyre failures, the latter limping round the final lap on three wheels to only just beat Max Verstappen to the line.

We spoke to former Mercedes F1 Design Engineer Gabriel Elias and former Mercedes aerodynamicist Miles Jackson, winners of six constructor titles with the team, to talk us through the changes which are coming in this year, how they will affect the cars and the teams, and why some areas are so sensitive for teams.

As Elias says, the alterations will be significant: “If you look at an overhead shots of 2021 cars, the combination of all those those features in the rear floor do a pretty damning job at ripping performance off the car,” he says. “All those things work together.”


2021 F1 Cost Cap

The greatest challenge facing F1 teams this year will in adjusting to the new cost cap, set at $145m (£103m).

It will reduce to $140m (£100m) in 2022 and $130m (£92m) in 2023.

All costs of running the teams are covered in this budget cap with the exception of: marketing costs, driver salaries, the salaries of the three highest earners at each team. The costs of employees’ maternity, paternity and sick leave are also excluded, in addition to the cost of medical benefits and redundancy packages.

In between now and 2024, teams are also allowed to incur up to $45m in ‘capital expenditure’ for things such as factory machinery.

The immediate dilemma is how much of the budget to allocate to next year’s car. Getting ahead for the start of a new set of regulations could offer an advantage for several years but teams won’t want to completely sacrifice the 2021 season.

As explained by the James Allison, Mercedes’ Technical Director, in his own take on the 2021 rules, the cost cap has made the jobs of teams that much harder.


How much can F1 teams use their wind tunnels in 2021?

In another bid to level the playing field, teams are now only allowed to use their wind tunnels for a certain amount of time. Last year’s bottom-placed team in the standings – Williams will be getting the most and Mercedes the least. The amount permitted for others moving on a sliding scale depending on championship position in five per cent increments.

It’s been calculated that Williams will be able to use their wind tunnel roughly 20 per cent more than Mercedes in 2021. Teams are adapting their R&D design processes to offset this as much as possible so that they make the most of every minute their cars are in the wind tunnel.


2021 F1 wind tunnel allowance

Teams’ previous season’s championship position Percentage of current aero testing allowed for 2021 Percentage of current aero testing allowed for 2022-25
1 90% 70%
2 92.5% 75%
3 95% 80%
4 97.5% 85%
5 100% 90%
6 102.5% 95%
7 105% 100%
8 107.5% 105%
9 110% 110%
10+ 112.5% 115%


What is the 2021 F1 development token system?

As of 2021, teams will be limited by what they can develop on the cars. This has been done in yet another bid to curb costs, and will be regulated by a token system. Teams will only have a certain number of tokens they can use throughout the season.

Whilst the teams are free to develop surface area dynamics throughout 2021, tokens will have to be used to evolve other areas of the car.

The FIA has issued a list of 40 F1 car components that will to have to be ‘frozen’ in their development at a particular point in the season, with teams barred from developing those parts from then onwards. A certain number of components will be frozen from R1 in Bahrain, whilst others will be frozen from R8, currently scheduled to be the French Grand Prix in June.

If a team wants to change any of those parts from that point onwards, it will have to use one of its allocated development tokens.

Different areas of the cars have been given differing development values. For example, bigger parts, such as front and rear suspension, have a value of two tokens.

If a piece only has a value of one token, it can be updated twice throughout the season.


What are the 2021 F1 aerodynamic and floor rule changes?

“The top of the diffuser surface, the inner flicks on the cake tins (brake disc enclosure) on the rear wheels, the floor’s volume, the rearward floor slots, and then the front ones too, have all been reduced or removed,” Elias says. “All those things combined make an absolutely huge difference. The question is how would you recover it?”

Rear Floor

The first significant area addressed is the car’s floor in front of the rear wing and down the side of the car. This baking tray-like structure previously featured various lateral and longitudinal slots.

McLaren 2021 comparison overhead

2021 McLaren floor is tapered and without the slots of last year’s car

The slots/inlets helped to generate downforce and, as a result, none are now not permitted in the entire rear section of the floor or down the side of the car.

The floor itself has additionally been pared back also, with two triangular cutouts on each side. This will reduce performance by roughly 1sec per lap.

Jackson details the previous function of the floor and what teams will try do to try and recover performance lost.

“Pre-2021 regulations, different cars would have different rake each creating their own kind of vortex [along the air] along the edge of the floor,” he says.

“The way that you form that vortex – you could break it up by having differentiating edges and things like that – you could change its behaviour and its strength.

“Now that there’s vortices off that, there’s vortices off the edge of the diffuser, when you’re next to the tyre, and also all those details around the tyre strakes in the lower deflector – which is on the wheel. All those vortices interact – all the details that we’ve had on there before were to basically control the vortex.”

Elias is in no doubt about the significant this rule change surrounding the floor is.

“The floor itself adds 60 per cent of the car’s total downforce,” he explains. “It’s the largest contributor and that’s why the rules have taken away floor area, as a way to really hit the teams hard and slow the cars down.”

How can teams recover this lost downforce?

“To recoup that, you got to come up with new ideas,” Jackson says.

“What will start to sprout up at the first races and throughout the year like that will be details, trims and flicks – there’s 50mm above the floor that you can play with.

“Where the floor has been cut away [to reduce downforce], you can do different things – you can notch it, you can kind of put a gurney on the edge, or you could flick it up so it becomes a sharp edge.

2021 Alfa Romeo C41

Diffuser strake height will trimmed in 2020, but no team has thus far revealed its full design


“Top floor detail as well as the edge will change a lot through the season – there’s lots of development potential in that area.”

McLaren’s first 2021 car images showed an undetailed, flat floor in front of the rear-wheels, but Jackson says few in the F1 design world have been fooled by this.

“Initially seeing these launches, like with the McLaren reveal, they had a floor and it was flat back there,” he comments. “That’s not what they’re going to drive, you’re not going show up and race with that floor.

“What they’ve shown in their launch videos is basically a dummy floor, because they don’t want to show their hand before the season starts and allow people to copy.”

Mercedes’s Allison admitted in the W12 launch video that its ‘2021’ car also didn’t reveal the full floor detail.

“Down there, there’s a bunch of aerodynamic detail that we’re not quite ready to release to the world – not because it’s not there, but because we don’t want our competitors to see it,” he said.

“We know they’ll be looking, we don’t want them starting to put similar things in their wind tunnels.

“We don’t have to show it yet, so we’re not! It just buys a couple of weeks extra.”


Rear floor load/flex rules

The rules on the amount of load the rear of the floor can take has been tightened up, as has the amount of flex which is allowed. Previously the rear floor was permitted a maximum flex of 10mm. This has now been reduced to 8mm when 500NM of load is applied.

Elias says that for a design engineer such as himself, the reduction of the floor space is a big headache.

“It would present some challenges from a design standpoint, as you’re trying to add structure into the floor but you now have less volume,” he notes. “So that can be very difficult.

“When I was at Mercedes, the questions I would ask would be: ‘How is the floor mounted? What kind of flicks, strakes and little features are there at the ends of the floor, and how are they manufactured?’

“Those kinds of little things actually end up affecting how you know the floor structurally, which is what I cared about.”

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The diffuser has also been reined in to lessen its potential to generate downforce. The strakes which create the ‘tunnels’ running down the back of the diffuser are now required to be 50mm shorter than they were last year.

Elias says the continuation of cars from last season could cause headaches in this area.

“If, for instance, your gearbox is carried over, which I’m pretty sure they have to be, then you’re essentially limited by it,” Elias explains.

“It limits the diffuser area in width as you approach the centre of the vehicle, and could potentially limit the height of the diffuser in certain areas.

“As far as how to make up the downforce, they’ll probably try to make it up elsewhere, maybe through a more aggressive tunnel shape on the floor.

“They could maybe add more strakes to help maximise the efficiency of the diffuser itself, which is something we’ve done at Mercedes in the past, change the shape of the strakes or try to recover by increasing the width of the diffuser across the floor.

“A team might also try to make a more aggressive expansion area on the diffuser size, perhaps further forward, or at least as far forward as the regulations allow you to do so.

“Ideally, teams will probably push the actual width of the diffuser tunnel itself as wide as possible within the rules and then probably the expansion area will go as forward as possible too.


Rear brake ducts

Rear view of the 2020 Racing Point RP20 F1 car

Aerodynamic features around the car’s rear wheel and brake ducts have also been modified

Grand Prix Photo

Winglets wider than 80mm, which previously were mounted in the lower half of the rear brake duct, are now banned also.

The width limit for winglets in the upper half of the brake duct now remains 120mm.

Jackson believes team’s might place additional winglets at the end of the floor in front of the rear tyres to compensate for this.

“They’ll be tyre strakes or little flicks in front of the tyre on top of the floor, those would probably be highly developed,” he says.

“The lower deflectors themselves [inside the ‘cake tin’ brake drums, next to the rear tyre], they’ll change shape and perhaps be modified in their purpose.”


How heavy are the 2021 F1 cars?

The minimum weight of the 2021 F1 cars has been increased by 3kg to 749kg. The main reason for this is the increase in weight of the tyres (more on this below).

At the same time, the minimum weight of the power unit has been increased also, going up to 150kg.


2021 F1 Pirelli tyres

F1 tyres underwent the greatest forces ever generated by a grand prix car in 2020.

As mentioned above, the result was a number of significant failures last year. To combat this, the 2021 Pirellis have been made more durable and therefore heavier.

This will affect both the handling of the cars and, of course, make them slower.

Mario Isola, Pirelli’s head of F1 and car racing, said that the company aimed to “improve the current construction in order to have more… integrity” in their tyres.

Elias highlights the constant battle between teams and tyre manufacturer.

“Pirelli’s job every year is almost to fight the teams – fighting us for downforce,” he said,

“Every year, as the downforce increases, their task becomes harder and harder because we’re applying more and more load and speed to these tyres.

Lewis Hamilton's punctured tyre smoiking on the final lap of the 2020 F1 British Grand Prix

Hamilton battles with his deflated left tyre on the final lap of the British GP

Florent Gooden / DPPI

“They probably just increased the tyre carcass thickness. You can imagine that it’s going to be very difficult to get these tyres into their operating temperature and into something that drivers will want to handle.”

Jackson believes that for aerodynamicists, the challenge presented by the new tyres is knock-on effect of their new durability.

“The change in shape of the carcass for us is of bigger magnitude than the weight,” he comments.

“If the outer shape of the tyre carcass changes, that can be huge. Even down the the mould marks, on the shoulder of the tyres, that can alter the aerodynamics.

“We do a lot of stuff with tyre shape stuff, in cornering it changes [shape], all these things.

“If the flex or the shape of it of that changes, that will probably be a bigger thing than the weight for us.”


2021 engine and engine modes

Teams will now only be permitted one engine development token in 2021. This is as opposed to the three they enjoyed in three they enjoyed last year. Teams are now under huge pressure to make sure they get their developments right, as they only get one go.

F1 outfits will also now be permitted to only have a set number of engine modes throughout the season i.e. qualifying – or ‘party mode’ as Lewis Hamilton put it – will now be banned.

For now five modes are permitted but these will be reduced year on year as the table below shows.

Team engine mode allowance

2021 2022 2023 2024 2025
ECU team applications 5 5 5 5 5
ECU PU applications 5 5 5 1 1
ERS & PU-CE applications 3 5 3 1 1


2021 F1 exhaust and tailpipe changes

Previously teams have been required to run at least one tailpipe attached to their wastegate system.

Now though, they are no longer required to run a tailpipe if they produce a system which does not require a wastegate.

More exotic exhausts have also been outlawed. Any cavities must now have a cylindrical shape of a constant diameter.

“Basically, the reason behind that is a lot of the teams actually don’t operate a wastegate,” says Elias.

“Wastegate pipes were introduced in 2016 – you can either have a single pipe or two split ones. These were introduced to help sound.

“However, wastegate is excess boost. If you have excess boost, you’re literally wasting power. Teams have just found a way to make these engines more and more efficient to the point where a wastegate wasn’t necessary.

“That assembly probably weights about 0.75kg. Mercedes had a very complicated wastegate assembly, so that’s a useful change.”


Will DAS be used in 2021?

The Dual Axis Steering system is banned for 2021. Mercedes’ 2020 innovation to generate front tyre-temperature was banned this year to stop teams getting into a development spending war.

As Elias points out, losing DAS could actually be inadvertently useful for Mercedes.

“DAS was obviously very useful to warm up the tyres,” he says. “But what I would say is that thing is really heavy. It’s kilos upon kilos on the front of the car – that is not a light system.

“Sometimes they used it warm-up the tyres very quickly after pitstop – that might make them more vulnerable at times – but something tells me the performance differential is still going to be great.”


Green materials now permitted in F1 for 2021

As part of F1’s push for a more ecologically-minded future, sustainable materials are now being permitted to be used in the construction of F1 cars.

These include bamboo, hemp, flax, cotton and bamboo. As well as being a greener alternative to carbon-fibre composites, these materials have less chances of shattering into dangerous shards when damaged.

“This change came so late that most teams will be very risk averse for putting something on a car that they don’t have actual like test data and R&D on,” says Elias.

“They’d be testing representative samples of the material, trying to pull it, break it, fatigue it, those kinds of things.

“Until that kind of a study is done in earnest, I bet you there’s not going to be a lot of uptake from it.

“That’s more of a nice thing for the for the news clippings.”



The number of specifications of fuel and lubricants used throughout the season has been pulled back. Only the previous season’s formulations and one new set being permitted for 2021.


FIA stops ‘Pink Mercedes’ repeat

The FIA has moved to make sure that there is no replay of Racing Point’s ‘Pink Mercedes’ scandal, when they appeared to almost exactly copy Mercedes’ 2019 challenger the W10, and did a pretty good job of it in the process.

A new addition to the regulations covers the ‘listed parts’ in greater detail, highlighting how a team might follow the design concept of another without directly copying it.

The rules re-emphasise that teams may only gather events on their competitors at events or tests, and that this information may potentially be available to all competitors.

The use reverse engineering techniques such as of 3D capture scanning tools have been banned. Now teams can only use video or photography and make a ‘best guess’ of the dimensions of the parts they might be inspired by.

If a team falls under the suspicion, the FIA can now request to see its entire design process.