Up until now, we have been talking about relatively short corners of about 90 degrees or less. For such corners, the tradtional track in, apex, and track out approach will yield the fastest times and highest exit speed. In longer corners, in particular those that involve 180 degree direction changes, this tradiational approach is not always best. Many such corners benefit from the double apex.

What is a double apex?
A double apex is exactly what it sounds like: 2 apexes in 1 corner. If that concept sounds odd, you’re right. It is a counterintuitive way of approaching a corner. But, as you will see, it can be the best option in some situations.

Why double apex a corner?
The short answer is because it is faster. Now lets look at the long answer.

Say you have a corner that is half of a circle, where you exit the corner facing 180 degrees from the direction you entered it. Big Bend at Lime Rock Park (aka Corner 1), is an excellent example of such a corner. If you take the traditional line through the corner, you turn in at the start of the corner, but apex very deep in the corner to ensure that your track out point is on the straightaway and not in the woods. The way to do this is to hug the outside edge of the track, and then turn in to make the apex. You therefore have 2 turn in points, in essense. The first, where you turn in at the start of the corner, and begin hugging the outside edge, and the second, where you turn in from the outside edge to make the apex.

The problem with this approach is that in the time between your first and second turn in points, you are simply coasting. Coasting in general is bad because it means you could be accelerating, or could have braked later. As you will see in a minute, you actually can be doing both in the same area and time that you would be coasting.

The Double Apex
Lets take this same corner, Big Bend at Lime Rock, but instead of treating it as 1 corner, we will treat it as 2, split right down the middle. For the first corner, lets call it Corner 1a, you would apex roughly halfway through this smaller corner, and track out at the middle of the larger corner, Big Bend. You would then turn in for the second corner, lets call it Corner 1b, apex roughly halfway through this smaller corner, and track out at the end of the larger corner, Big Bend.

What have we gained by treating the corner this way?
By making 2 corners out of Big Bend, we have given ourselves an extra acceleration zone, at the end of Corner 1a. This gets us through the section that we would otherwise be coasting through much quicker.

This acceleration comes at a price, however, which is the need for a braking zone at the start of Corner 1b. Since we will be turning throughout all of Big Bend, whether we double or single apex the corner, we will need to trailbrake at the start of Corner 1b. As you will recall from The Line, Part 5: Trailbraking, trailbraking is a compromise between turning and braking. Thus, our acceleration zone is limited by the need to trailbrake through the start of Corner 1b.

The dangers of trailbraking should also be remembered and factored into whether to double apex. On slower corners, such as Big Bend, the stakes are much less than on a long, high speed 180 degree corner.

There is no hard and fast rule on which long corners are best double apexed. Each corner is different, and each car has different nuances that may make a double or single apex better in a particular corner. The Bowl, at NHIS (Corner 6), for example, is a tight 180 degree corner that is best single apexed. The best thing to do is to try a long corner both ways and see which technique works best.

The double apex can be a bit difficult to grasp at first, but, when perfected, can be a very useful technique for an otherwise long and slow corner.