Imagine a race car weighs 1,000 kilos. On a flat surface, without elevation changes, this weight will remain more or less the same on the tires. If the track starts going up on a compression, for the moment of the compression, the tires will compress more. We'd say 1,500 kilos. This means more grip. In compressions, we can accelerate more, break more, turn more. If the track starts falling away from the car, which is what we call a crest, the tires will compress much less. Let's say 500 kilos. This means less grip. In crests or decompressions, we can accelerate less, break less, turn less.

If the crest is extreme enough, the car would completely disconnect from the track and jump, which means we cannot break at all, accelerate at all, or turn at all. Just like it's impossible to turn or slow down at all during a jump, it's more difficult to turn or slow down on a crest. This is important. We might think this concept is easy to understand, but we fail to identify it when the changes are subtle. For example, many braking zones will look flat, but they might have tiny changes in elevation that might change your braking grip limit considerably.

Extreme Examples of Elevation Changes

Breaking on a Compression

In this example, breaking at 100% going up or rush shows no sign at all of locking or microlocking. In this case, it would be possible to break even 110% or 120% if the simulator allowed, and still not lock up the tires.

Breaking on a Crest

In this example, breaking at 100% on top of Hadion results in instant lockup. In this case, breaking at even 80% would still cause lockup.

Changing Conditions in the Same Braking Zone

It's possible to have changing conditions in the same braking zone. In this example, we start breaking 100% on the compression, but the compression becomes a crest later, and as soon as the car gets light, we instantly lock up the tires. This is a famous corner, where most drivers don't realize the changing grip later into the corner, mostly because it's so late that we're already thinking about the corner and starting to trailbreak.

The Corkscrew at Laguna Seca

Another great example is the corkscrew at Laguna Seca, where the beginning of the brake is flat, but then immediately becomes a crest and then it gets flat again while going downhill. In this case, the braking trace should go up initially, then decrease when we go through the crest, and then we have some time to still reapply the brakes a little bit more to control more speed before turning in.

Turn 1 at Koda

Turn 1 at Koda is also tricky. The beginning of the brake is a huge compression with a lot of grip, and then becomes a crest that makes most unaware drivers lock up later into the corner at the turning point.

Clarifying Misconceptions About Elevation Changes

Crests and compressions are not related to uphill or downhill. Crest does not only mean going from uphill to downhill. Compression does not only mean going from downhill to uphill.

• You can still go downhill and find a compression and then still be going downhill just less

• You can also be going downhill, find a crest, and then find yourself going more downhill than before

• You can also be going uphill, find a compression, and go even more uphill

• You can be going uphill, find a crest, and then find yourself still going uphill just a little bit less

The effects of going flat uphill or flat downhill are much more subtle and are not the point of this lesson. The change in the angle of the road is what will heavily affect the grip of the car.

More Subtle Scenarios

Nurburgring Hairpin

The braking into this hairpin at Nurburgring is a compression, and way too many drivers miss it and don't benefit from the extra braking grip. Most drivers end up braking just as much as they do on turn 1, which is obviously a crest on the braking.

Practicing Without ABS

If you want to try exercising these braking grip levels, make sure you're trying them without ABS. This will help you identify where there is grip and where there isn't, and this will help you even when you get back to cars with ABS, since abusing ABS is really bad for you, especially in eracing, and decreases your own driving precision and the amount of available grip during the corner.

Identifying Small Details in Elevation

Reading Track Visibility

We can see the track all the way into a certain point, but then from there we can't see anything anymore. We see the white line, we see everything, but then we kind of like can't see the corner. That's because we have a crest—the car is going to start falling down and the car is going to get light and we won't get as much grip as we have at the beginning, because at the beginning we can see all the track.

When we can see that the track is going up a little bit for the duration of the change in the elevation of the white line, we're going to have more grip there, because the car is going to be compressing against the track. So whenever we see more of the track and the line is going up, we know there's going to be more grip. But whenever we don't see anything after, we know there's going to be less grip.

Adapting Braking to Elevation Changes

On the beginning of the braking, there's more grip. Breaking very hard is appropriate because we're still in the compression. But then right after, there's going to be a lot less grip, so the braking must go down very quickly. This means releasing the brakes as if driving a formula car, but actually driving a GT car in a place where there's less grip. A lot of grip at the beginning, and then absolutely no grip at the crest. Barely turning, but already releasing the brakes heavily, because we're on top of a crest.

However, after the crest, the track often becomes quite flat. There's going to be more grip in the next fractions of a second compared to where we are at the crest. The brakes can actually go up a tiny bit, or kind of flatten. This flat line on the braking happens because there's a little bit more grip in that area. Basically: a lot of grip, then no grip (a little bit blind falling, light), and then back to flat. The rest of the corner can be done normally with normal release.

Subtle Camber and Compression

Under braking in another example, we can see a lot of the track. There's a very, very, very subtle camber to the right, and a very subtle compression going up when starting to brake. When we brake, we can brake pretty hard. We're on top of a compression. It's very subtle, but it becomes more noticeable with practice.

After this point, we can see less of the track around a certain area. That's because the inside is falling a little bit. By the time we start crossing, we can see a lot of an area because it's off camber. The track is effectively going from one elevation to another. Because we're going to be crossing from one to the other, this is effectively a crest and we're going to have to brake a lot less. Releasing the brakes more quickly by the time we get there is necessary. The brakes drop significantly, and then trail braking continues normally.

Exit Elevation Changes

On exits, we sometimes can't see the grass very well. We see the track and then we see already the wall. We see the track and the wall, but we don't see the grass. That's because there's an elevation change right there. When we finally can see, we know that on this exit the car is going to get very light.

Reading the White Line

We see the white line. The white line is actually going down and then up a little bit. Tiny bit, very subtle. This means there's more grip by the time we turn in. And then it becomes kind of flat.

Under braking in another section, we have a little compression. There's a little bit more grip, so we can break a little bit harder. But then when we start turning into the corner, the corner kind of like becomes a NASCAR cambered corner. There's a lot of banking. But every time we transition from the bit that is flat to the bit that is banked, there's going to be a jump because we're going to go from one elevation to another. This causes a jump and a big drop on the brakes is necessary because there's going to be a lot less grip at that transition. Then back to trail braking normally, because there's a lot of grip mid-corner.

Back on power, the same principle applies. We can see a little bit less of the left side of the track because it's slightly, slightly off cambered. This means just a little bit less grip. The car falls a little bit, requiring a little bit of correction.