The Racing Line

One of the the first fundamentals of going quickly as a racer is the racing line. The “line” is what dictates your overall speed through a corner and requires a decent understanding of physics to master, since it is tied to more complicated concepts such as increasing/diminishing grip, traction and vehicle rotation. When it rains or when competitors are involved, knowledge of more than one racing line is crucial to getting the best performance possible. Most discussion rarely delves into some of the more juicy details, so here, we’ll touch on both the basic and the specific concepts to ensure a comprehensive understanding of the topic.

Generally speaking, the straightest line is the quickest line through the corner. When entering the corner, the apt driver will position their car on the outside, turn in and brush the inside of during the middle of the corner, then unwind the steering wheel as they exit the corner, returning to the outside and applying the throttle gently in the process. By maximizing the width of the track and therefore the radius traveled through the corner, the driver puts less strain on the tires and can thus apply the power earlier and brake later. This approach is what many will refer to as the “out-in-out” line and this applies for most corners on any racetrack.

Things get more complicated with a sequence of corners. The driver ought to place precedence on the corner which is either preceded or followed by the a straight. Straight sections of road are important since they allow for easy accumulation of speed. In other words, a good exit onto a long straight will reap the largest, most easily-attained gains. This is because driving a straight features lots of full-throttle.

Therefore, when two corners precede a straight, an intelligent driver will compromise the exit of the first corner slightly so that they can take the second corner as efficiently as possible. This approach reduces the speed through the first corner but allows for the second corner to be taken quickly. That speed is then multiplied down the subsequent straightaway.

drive line
Notice how the lines differ through two similarly-shaped corners due to the following straight.

This is all elementary but in the real world, there are other factors which dictate the quickest way through a corner. The apex, or the point at which the driver clips the inside of the corner, can vary in placement based on the shape of the corner. A corner with a constant arc will have the apex directly in the center of the corner. Tighter, late-apex corners require the driver to enter on a wide line at a slower pace, turn in abruptly to rotate the car and accelerate. These corners are typically quite slow and their apexes are further beyond the “geometric center” than medium-speed or fast corners. With late-apex corners, the patience involved in delaying the throttle application and arriving at the apex with the right attitude can be off-putting to the initiate. However, any overly eager novice will quickly understand this concept when a patient competitor carries better speed out of the corner and passes them. By the same token, fast corners typically feature an early apex.

Aside from the shape of the corner, surface nuances will determine the ideal line as well. Bumps and cracks can throw the car sideways, damage the car or cause the driver to lift off the throttle. If the textbook line happens to cross over upsetting surface anomalies, the actual line ought to best avoid them. When this is impossible or impractical, an astute driver will improvise, and, for instance, apply the throttle more slowly over an unsettling bump so that the car doesn’t break loose. In addition, surfaces covered in oil, rubber or water can seriously affect speed and need to be taken into consideration.

As drivers push their tires through a corner, the frictional forces involved will cause the tire to disintegrate slowly and throw off small chunks. These pieces are known as “marbles”, which collect off-line and are best avoided. Often the mistake of taking too wide a line will force the driver onto these marbles, which, hence their name, are quite slippery. The rubber which doesn’t actually fly off the carcass gets deposited into the road surface, on the racing line. As the day goes on and – to a point – the track gets hotter, this rubber makes for a grippier surface. In the rain, however, this all changes.

drive line
Notice how the rain line avoids the entry phase of the dry line. Exiting on the same line is only possible when there’s enough grip.

Those impregnated rubber deposits, when slicked with rain, become incredibly slippery. Therefore, the “dry” line becomes perilous when it’s wet out and the astute driver will search off-line for grip, taking a route which allows for a reasonable radius through the corner but avoids the slick patches. In the real world, improvisation is needed to figure out where the ideal line is. Generally speaking, the corner is approached one or two car lengths inside the traditional line, crossing over the dry line at the apex for as little time as possible before exiting again on the inside of the conventional line. This approach needs to be tailored for different circuits but generally holds true.

Curbs also affect the shape of the racing line. Depending on the size of the curbs, some can be used to your advantage whereas others are wisely avoided – especially the steeper ones. Driving curbs becomes an art in itself since the curb can help or hinder your progression. Typically using the curbs is done to open up the track as much as possible; allowing for a straighter line through the corner. However, tall or serrated curbs can upset the car and cause a time-sapping slide. In addition, using too much of the curb can upset the airflow underneath the car which will reduce grip if the car is aerodynamically dependent.

Ultimately, the driver has a style which works best for them and certain subjective considerations have to be made. Many drivers prefer to try and turn in early, which compromises entry speed, tends to use the front tires a more but protects their position on track. Some drivers like to pitch the car in late and take a sharper line through the corner, which tends to wear the rears rapidly but often is the quickest way through a corner. Though all the aforementioned theory has a place in shaping a driver’s approach, what feels comfortable to them will affect their lines.

late apex drive line
Late apexes should be taken in tightening or hairpin corners or with cars that exhibit understeer.

To drive the car at the limit lap after lap, the driving line and all of its facets must be taken into consideration constantly. Negotiating traffic, learning to concede a corner to an adversary when approaching on a compromised line and setting pole position all depend on a thorough understanding of the racing line and what it entails. When it comes to racing, theory is a valuable thing to understand but, as we’ve discussed, variables such as driver preference and surface conditions determine the ideal way through the corner. Study up and test out your theories, as feel and experience are the only things which will assist you when it comes time to compete.

About Tommy Parry 124 Articles
Tommy Parry has been racing and writing about racing cars for the past seven years. As an automotive enthusiast from a young age, Tommy worked jobs revolving around cars throughout high school and tried his hand on the race track on his twentieth birthday. After winning his first outdoor kart race, he began working as an apprentice mechanic to amateur racers in the Bay Area to sharpen his mechanical understanding. He has worked as a trackday instructor and automotive writer since 2012 and continues to race karts, formula cars, sedans and rally cars in the San Francisco region.

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