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The Undercut, The Overcut & The Double-Stack: F1 Pit Stops

F1 pit stops are masterpieces of both engineering and teamwork. They are completed in just a few seconds, yet so much about the car can be changed in that short space of time. But there is a lot of strategy involved in F1 pit stops, with three main types helping teams gain an advantage over rivals.

The undercut pit stop involves a chasing car pitting before the car in front, and then using the fresh tire advantage he now has to close the gap before the leading driver pits. The idea is that when the leading driver does pit and then rejoins, the chasing driver manages to overtake him.

The overcut pitstop is essentially the opposite of the undercut. It is rarely used, but it involves a chasing car letting the car in front pit first. While they are pitting, the chasing car builds up a gap between them, in the hopes that they stay ahead even after they themselves pit.

The double-stack pit stop involves a team pitting both of its drivers at the same time, with one car going through a regular pit stop first, and the second car being pitted immediately afterwards. It is used very rarely, and it involves a lot of precision in order to get everything right.

Each of these three types is used by each team at different times in different races. Each one occurs under a certain set of circumstances and needs to be carried out with a lot of precision in order to ensure things go smoothly. First, let’s go over the basics of an F1 pit stop.

Why Are Pit Stops Needed In F1?

Pit stops are common across a lot of motorsports, with varying uses and styles. F1 pit stops tend to be much faster than other motorsports, with the fastest coming in 2019 at the Brazilian Grand Prix when Red Bull’s Max Verstappen pitted in just 1.82 seconds. Similar times are a regular occurrence now in Formula 1, but most stops take between 2 and 3 seconds to complete.

Generally, anything above 2.5 seconds can be considered slow, as every millisecond counts in a race. These times are only achievable as the pit stops in F1 tend to only involve a change of tires. Some stops can take longer, such as if there are repairs required for the car, or if it needs a wing replaced. A front wing replacement may still take less than 10 seconds if performed efficiently.

Other Motorsports

They are often compared to the pit stop times in NASCAR and IndyCar, which can take 12+ seconds to complete. However, these stops often involve refueling, something that has been banned in F1 since 2009. Pit stops are carried out by mechanics, with two cars for each team each having a pit crew of more than 20 people, although not all are required for each pit stop.

A Standard Pit Stop

Basic pit stops involve a change of four tires, and they usually occur at least once in each race. It is theoretically possible to last a full race on a set of intermediate or wet (very durable) tires, but this is not a desirable strategy due to a lack of pace and excessive tire wear. Thus, teams will often weigh up a one-stop and two-stop strategy depending on the track, with some occasions requiring three.

Although pitting will sometimes result in you losing track position, you will tend to be able to make it up as everyone else will usually need to pit as well. This is where it can become a tactical battle of pitting less often than your rivals if you can, so that you can save or make up time on them. But this all comes down to the tires being used, as they each have their own advantages and disadvantages.

Different Tire Compounds

Usually teams are required to use at least two different compounds throughout a race, but the exception to this is when it rains, as they can use whatever they want. The main compounds are soft, medium and hard. Soft tires provide better grip and thus faster lap times, but at the cost of excessive wear, and they can often last just a few laps, although they can sometimes go 20 or more.

Hard tires on the other hand may last 40 or more laps, but they can be nearly 2 seconds per lap slower than the soft tires. The medium tires are somewhere in the middle, and then there are also wet and intermediate tires. These are only used in wet track conditions and are treaded. This is in contrast to the soft, medium and hard compounds, which are all slick tires with no tread.

Speed vs Tire Wear

Thus, with soft tires, you have the advantage of speed, but you will need to pit sooner than someone with medium or hard tires on. It then becomes a tactical battle of trying to gauge when other teams are going to pit, and on which tire compound they will be racing at certain times to try and gain a tactical advantage using the pit stops which we will discuss below.

Different tracks come with their own set of conditions. Hot temperatures will cause tires to wear faster, and so will high downforce tracks. These are tracks that have lots of fast corners that require a lot of downforce, and thus a lot of grip. This enhanced downforce however means the tires are under more strain, which can result in fewer laps being run on each compound.

Optimum Temperature

Tires also have an optimum temperature range for maximum grip. When they get too hot, they wear easily, but when they are too cold, they don’t offer much grip. This means that although fresh tires tend to provide a good advantage over very worn ones right out of the pits, they still need to get up to temperature, which can take anywhere from a few corners to a full lap.

F1 racing is very much a tactical game of chess, which involves paying attention to the track conditions and what moves the other teams are making in terms of tire choice. We will go through the various types of pit stop soon, but first we will quickly go over the basic anatomy of an F1 pitstop, and what each one involves.

The Basics Of An F1 Pit Stop

Into The Pits

The first thing the driver will do is come off the track and into the pit lane. At a certain point, he will need to reduce his speed to around 80kmph/50mph, and then approach his designated pit box. His mechanics will be waiting for him here in position, ready to get to work as soon as he stops. For the sake of simplicity, we will just be considering a standard tire change pit stop here.

As he slows to a stop, one mechanic puts a jack underneath the front of the car, with another does the same at the back. They do this as soon as the driver stops, and then even as the car is being lifted by the jacks, there is a tire man at each wheel operating a pneumatic wheel gun that removes the wheel nut from the wheel. There are three mechanics in total at each wheel.

The Tire Men

One of the other two mechanics at each wheel removes the old tire as soon as the wheel nut is removed, and the other puts the new tire on, ready to be attached by the mechanic with the wheel gun. With two jack men and three tire men at each wheel, we already have 14 mechanics in the picture. We also have one on each side holding the car steady as the wheel gun is operated.

There is another mechanic with a fire extinguisher should something go wrong, and then there are two more on hand in case the front wing needs to be changed. Finally, there is a spotter watching the pit lane for other cars, and sometimes another spotter looking to make sure everything is running smoothly. This makes for a total of 20 mechanics, but this number can vary by team and by pit stop.

Complexity & Precision

These mechanics all work in a perfectly choreographed fashion to make sure that the four tires are removed and replaced in as little as two seconds. As soon as they are finished, there is a traffic light above the car that changes from red to green and the driver heads back onto the track via the pit lane, where he can then get back up to speed.

If all goes to plan, the entire process from pit entry to pit exit can take around 20-30 seconds, although each track will have its own average pit stop duration, as some tracks have longer pit lanes than others. So, now that you know what happens during a pit stop, let’s go into more detail about the different types that the teams can use.

What Is An Undercut In F1?

An undercut in F1 is when a driver pits sooner than a car in front of them to benefit from faster lap times on fresher tires. When they do this, they can close the gap to the driver in front who is likely going slower on older tires, until they pit and come out on cold tires that offer less grip.

The Most Common Strategy

The undercut is the most common pit stop strategy to be used in F1 races. It relies on the advantage gained by putting fresh tires on the car, and also relies on the car in front not pitting on the very next lap. Even if that is the case, the chasing car can still use the undercut to make up some time against his rival ahead.

Essentially, the process involves paying attention to the tire performance levels of the chasing car, and gauging that of the car in front. If the chasing car is beginning to lose a lot of time due to tire degradation, they can usually be sure that the leading car is too. The idea is to pit before they decide to pit, and then use the extra grip of the fresh tires to make up some time before the lead car pits.

Closing The Gap

Obviously, the lead car will increase their advantage while the chasing car pits, but the strategy relies on the lead car then pitting as well. If the chasing car manages to make up enough time, when the lead car pits, the chasing car should be able to get past them. This strategy can only be used when the gap between the lead and chasing car is around 2 seconds, for a very simple reason.

As we have said, tire wear is a crucial element of any F1 race. Each tire compound will lose a certain amount of performance each lap, and this can translate into slower lap times. If the tire is losing hundredths or tenths of a second worth performance with each passing lap, over the course of many laps in a race this can equate to several seconds of lost time.

Careful Calculations

Thus, pit stops can be the more favorable option, as they might lose the driver 18 seconds for example, but tire wear may lose them 20 seconds by the end of the race. Fresh tires thus provide a faster pace, with fresh hard tires often even being faster than worn soft tires. For explanatory purposes, let’s say the worn tire is costing both drivers a second each lap.

If the chasing car is within 2 seconds of the lead car, and then pits for fresh tires, he loses around 20 seconds of time – along with his track position in most cases – but removes this handicap of a second with each lap due to tire wear. Thus, when he comes back on the track, he has a one second advantage per lap over the lead driver, who is still using the worn tires.

Gaining The Advantage

Thus, if the lead driver doesn’t pit for another two laps, the chasing driver should theoretically close the 2 second gap (although he may still be 20 seconds behind the leader, he is no longer 22 seconds behind). Then, when the lead driver has pitted (taking around 20 seconds), he will find that the chasing driver has managed to overtake him while he was in the pits.

This obviously involves more variables than a simple pit stop however, as the chasing driver needs to make sure he doesn’t get caught up in traffic as he tries to regain his position, or if he needs to get past slow drivers that are a lap behind. If their pit stop ends up being slower than that of the lead driver, they may have more work to do as well and have to go even faster.

A Specific Set Of Circumstances

Thus, there is a very small-time margin that allows for this strategy. Plus, it can be easily combatted by the lead driver. Aside from having a much faster pit stop time, the lead driver can also remove the advantage by pitting immediately on the next lap. This means the chasing driver might only manage to make up one second of the 2 second gap, and still end up behind the leader as he leaves the pits.

If the lead driver still has a lot of life left in his tires, he can instead just keep pushing to make the gap even bigger. However, this can put even more strain on the already worn tires, and thus is a risky strategy. This makes pitting immediately often the more favorable option, and hoping the chasing driver didn’t manage to close the gap.

What Is An Overcut In F1?

An overcut in F1 is when a driver pits a lap or more later than a driver in front to try and close the gap between them by driving faster in what is now clean air ahead of them. The overcut is used far less often than the undercut in F1, but we do still sometimes see drivers employ the strategy.

The overcut is essentially the opposite of the undercut, in that it involves letting the leading car pit first, and then taking advantage of the clean air in front of them to build up a gap in the other direction so that when the chasing car does eventually pit, they still come out of the pits ahead of the driver that was originally in front.

The idea is that while the leading car is in the pits, the chasing car pushes their car to create a gap between them and what was the leading car when it rejoins the race. While the leader spends a lap or so getting their fresh tires up to temperature, the now leading car tries to take advantage. However, their tires will be worn at this stage, making it much harder to do for extended periods.

Tire Performance Is Critical

Thus, the chasing car needs to rely on the lead car being on a softer tire before they pit, or that they have more life left in their tires so that they won’t need to pit themselves for a few more laps. Because this strategy relies so much on tire performance, it is only really viable at tracks where tire degradation is less of an issue, such as cooler tracks and those with fewer fast corners.

The benefit to the chasing car that is now in front is that they know they are going to be pitting soon, and so don’t need to worry too much about managing their tires. This allows them to push harder than they normally would, which is essential for creating a gap. If they are on a harder tire than the now chasing car, they can also try to go slower but longer before pitting.

Going Long

This is a variant of the overcut, and instead of pitting shortly after the original lead car, they manage the tires for as many laps as possible. Although this then builds up a gap, and they may end up coming out of the pits behind the original leader, they will do so on fresh tires. Thus, they have lost track position, but have the tire performance advantage for the remainder of the race.

However, this requires a lot of extra tire management. Plus, the original leader can combat the strategy by managing the gap and keeping up the pace. This allows them to either overtake their rival when they eventually pit, or shortly after it on their still relatively fresh tires, as the other car needs to get some temperature into their tires after pitting.

F1 Overcut vs Undercut

The undercut is more common than the overcut in F1. This is because the undercut allows the trailing driver to make the first move, while to perform an overcut the driver has to wait for the driver in front to pit, and so the overcut relies on other drivers pitting sooner, which teams can’t control.

The Double-Stack Pit Stop

The double stack pit stop involves pitting both drivers in the same team on the same lap one after the other. It works out to be two pit stops in one, and when performed effectively it can be very impressive to watch and tactically advantageous as well, but it’s rare to see it performed perfectly.

It is very risky, as it involves the same mechanics doing both cars in succession. This means there needs to be two sets of tires in the pit box, which could quite easily end up being put in the wrong places or on the wrong car. Everything needs to happen so quickly too, so that neither car loses any time. This means there are only very specific situations when it can be performed safely.

The Right Gap

The gap between the two cars needs to be around the same as the amount of time it takes for the cars to make a pit stop. This is going to be around 2 seconds, but obviously if the pit stop for the first car then takes longer than that, the second car is going to be held up in the pit lane. This means both cars lose out, which can negate the benefit of performing the double-stack in the first place.

It is usually not a planned strategy and is only deployed in very specific circumstances. It is usually a reaction to other drivers, rather than the undercut and overcut strategies which are used to get the edge over rivals in front. Instead, this strategy can be used to prevent being undercut, and to prevent your drivers from undercutting each other. This is best explained with an example.

The 2019 Chinese GP

One of the few cases of a successful double-stack pit stop came in 2019 at the Chinese Grand Prix. Mercedes drivers Lewis Hamilton and Valtteri Bottas were in P1 and P2 respectively, with Sebastian Vettel behind in P3. Further back, Max Verstappen of Red Bull pitted for a second time, which triggered Ferrari to do the same, putting him in a position to undercut Valtteri Bottas.

In order to defend against the surprise undercut from Vettel, Mercedes needed to pit Valtteri. But if they did this, they would then have him undercutting race leader and teammate Lewis Hamilton. The team did not want to upset the order and cause unnecessary complexity in the race between those two, so they decided to pit both of them at the same time.

The Perfect Gap

The gap between Lewis and Valtteri was just enough that they could pit Lewis on the next lap and have Valtteri follow him into the pit lane. They performed two perfect pit stops, which meant Lewis stayed ahead and Valtteri didn’t need to lose any time in the pit lane. He did come out of the pit lane in third place behind Charles Leclerc, but he eventually managed to get past him to finish second.

Doesn’t Always Go To Plan

This meant that Mercedes managed to retain the race win and maintain a 1st and 2nd place finish for the third time that season. But it doesn’t always go to plan, as Ferrari found out at that year’s Abu Dhabi Grand Prix. In that case, they pitted Leclerc and then Vettel, whose left front tire took longer than usual to put on and cost him around four seconds.

The double-stack puts a lot of pressure on the mechanics, and it is very easy for something to go wrong. Thus, it is rarely seen in F1. Nonetheless, it is still spectacular to see when it is done correctly, and it involves a lot of concentration from everyone involved.

Final Thoughts

F1 pit stops are some of the fastest in all of motorsport. Around 20 mechanics take part in each, and they manage to change four tires in around 2 seconds each time. However, some situations call for some real strategy when it comes to pit stops. The main factor in pit stop strategy is tire wear, and over the course of a race tire management is the key to success.

The undercut pit strategy is used by chasing cars to close gaps between them and leading cars, and the overcut is used for the same reason. They both require specific circumstances and can be countered quite easily by the defending driver. The double-stack is the most complex type of pit stop, and for this reason it is rarely used, although it is great to watch.