Determining The Racing Line
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Introduction to the racing line
The racing line is the imaginary line a driver should follow to get the fastest time round a corner. The basic assumption is that a straight line between two points is usually the quickest route. The tighter the corner, the slower you'll have to go to get round without losing grip. By using all the space on the track, you can usually create a straighter route, and thus keep the speed up. However, there are various additional factors which determine the perfect racing line which are discussed below.
When cornering on a track, there are various factors to consider when choosing your line:
It is important to remember that there is rarely a perfect line through any corner for all conditions. It depends on the characteristics of your car, your cornering strategy, and the conditions. You should experiment with different lines and learn from people who know the track well.
Flash movie: A car taking the racing line
Braking point
How good are your brakes? How quickly can you reduce your speed from 100mph to 40? How does your car behave when the front wheels are locked? How brave are you feeling? All these factors determine your braking point. It's a sensible strategy to brake earlier as you're learning the track and your car, and progressively shorten the braking area as your experience grows. The rule of thumb is to get most of the braking out of the way before turning into a corner, although a light brake pressure on entry can help to reduce understeer and can give a better turn in (this is known as trail braking). Threshold braking is the technique you should aim for, but if the wheels do lock, quickly ease off and reapply the brakes with slightly less pressure until you get it right.
Never turn in when any of the wheels are locked, for more information, please see the braking section.
Turn in point
To get the line right, it is vital to turn in at the correct point. Leave it too late and you'll miss the apex, too soon and you'll have to tighten your line mid corner. Get this right and you'll have set yourself up for a good corner.
Apex
This is where it gets a bit more tricky. There are two different types of apex, the geometrical apex (fixed), and the racing apex (fluid). The geometric apex of a constant radius corner is the central point of the corner, which may also be the racing apex, depending on the context. Confusing!
This is where your strategy comes into it. There are two generic strategies for cornering:
- Carrying speed
- Getting the power on early.
Carrying speed
To carry maximum speed through a corner, you need to take the route that minimises the corner radius, thus minimising cornering force and frees up precious grip for keeping the speed up. This route tends to apex near the geometric apex of the corner as is usually know as the classic racing line (Figure 1). In Figure 1, the bend illustrated is a constant radius 90 degree right hander and the geometric apex is exactly half way around the corner.
Figure 1: The classic racing line
Getting the power on early
Oddly enough, carrying the most speed round some corners may not be the quickest way around a track. If the corner leads onto a straight it may be better to take a late apex, straighten the car out early and get the power on for a high speed exit (Figure 2). This strategy is the best for road driving as it gives you the best view of oncoming traffic before committing to the line.
Figure 2: The racing apex (classic line in red)
Hairpins
A hairpin is a corner which turns 180 degrees. In this case, the apex for the racing line is about three quarters of the way around the bend (see Figure 3).
The position of the next corner
The position and direction of the next corner will also affect the apex, for example, if the next bend is a left hander you'll need to move over to the right hand side of the track, and thus will need to apex later. If the next corner is another right hander an early apex would be more appropriate.