When trying to trailbrake for the first time, trying to apply the string theory thing on track, you might probably have spun the car right away on the internet, like, whoa, how did that happen? Why did that happen? There's a reason for that, and this is what this lesson is about.

The Two Functions of Braking

Basically, braking has two functions. We can decelerate the car, or if we are turning, the braking now gains a new function. We can rotate the car. The braking will amplify the amount of rotation capability that the front tires have.

So if you're turning X, and you get into the corner, the car is going to turn X. But if you're turning X, and you add brakes a little bit, not too much, then the car is going to turn more, like 1.5x, even with the same steering.

How Braking Creates Rotation

Because when you start braking, the inertia shifts the weight to the front tires. The front tires compress more against the track as the steering is pointing to the track, which makes the car point more. At the same time, that the rear tires are going up, and they have less contact with the track, so they resist less to rotation.

So if you're turning a little bit, and you suddenly add brakes, you're going to see immediately that the rotation is amplified. So the brakes amplify the steering, and this is the rotation function that comes from the brake.

You Always Get Both Functions

The thing though, and here is why this is so complicated, is that you always get both. If you are turning, and then you add brakes with the intention of decelerating, you also get the rotation. So if you need to brake in turn, you have to relax your hands and turn less. Because otherwise, the amount of rotation that you gain, the rotation boost is way too big, and it's uncontrollable if you're not aware of it, if you're not expecting it.

When cornering, you always have both, you have the rotation, and the deceleration. Of course, you want to brake a little bit less, because you don't want to over-slow the car with corner, right? You're already probably in the right workable speed range. What you just want to do is get the front to point a little bit more.

Brake Pressure Differences

And that's why, when we're braking only for rotation, we break very low amounts, we break 5%, 10%, 15%. But if we're braking with the sole intention of decelerating, then we're threshold braking, we're braking very hard.

The Transition From Deceleration to Rotation

Of course, it's not like we're going to brake super hard on straight line, and then as soon as you start turning, we drop the brakes very quickly to like 1, 2, 5, 10%. This is a very common mistake for people to just drop the brakes very quickly, and not do a smooth transition.

What you want to do, is do a transition from the deceleration function to the rotation function. And that's how you're going to build that lovely closing spiral. It's by doing a slower transition, that you're going to maintain the grip usage at 100% during the transition.

And that's the most difficult thing to do in motorsports. You reach peak grip on deceleration, on entry, and you can reach peak grip mid-corner on the rotation deeper into the corner like at the MRP. But the challenge is maintaining the 100% in between, transition between the deceleration function towards the rotation function.

So if you're the kind of driver that breaks 100% or very hard, and then drops the brakes very quickly as you turn in, and you see that quick drop in the geometry, that means that there's some place in between where you're not on the limit, or you were over the limit before you drop the brakes.

Sometimes it can get very complicated, because you only intend for the rotation, and you end up getting the deceleration, whether you want it or not.

The Standard Braking Shape

Now in 99% of the corners, you're going to see a braking shape that looks like this. So initially we have peak deceleration, and here at the end we have peak rotation. So the rotation function depends on the amount of braking pressure. If you're braking a lot, then you're getting a lot of deceleration, if you're braking less, you're getting a lot of rotation.

We generally want to get the deceleration first. Like literally 99% of the corners you're going to bring the speed down, using the braking to decelerate the car, and then as it transition down now the deceleration function decreases, and the rotation function increases.

What Happens With Incorrect Brake Application

So if you try to do something like, I don't know, this, it's not going to work well. Because right here, you're way under the limit, because you're not braking hard enough, the car is going too fast, then you realize that you need to stop more, because you're too fast, and the car is not turning or something.

Then around here, when you start adding more brakes, the car will probably go through a very weird phase of possible oversteer, and even spin. And if you don't spin, by the time you get here, you're already kind of going wide, or like the car is all over the place. And then if you hit too hard, here, you're probably going to lock the front tires and go straight.

So it looks like this, oversteer, and then it locks, and understeers. Of course, if you have ABS, then you can kind of steal to the corner, and that's the problem of ABS, it kind of hides your problems. There's a lot of people doing this trace, and not realizing that it's wrong, because the car is forgiving it.

If you do the trace, in a car that does not forgive you, you're either spinning here, because of this medium pressure, that's giving a lot of grip to the front tires, or you're locking up and going straight here, because of the high pressure, that at lower speeds is probably going to lock the front tires, and you're going to go straight.

Different Braking Shapes Based on Speed

Now, depending on the speed that you're bringing before this corner, your brake will have different shapes. So if you're carrying a lot of speed, and you need a lot of straight line braking, then your trace is probably going to look like this. You're going to have a threshold here, where the function is solely decelerating, and then you start doing the trail braking.

Now, if you're carrying not so much speed, and you don't need to do the threshold, it's possible that you were already going to start braking halfway. So instead of going to say this, you're going to brake only this.

Common Misconception About Braking at Lower Speeds

It's a very common misconception for people to think that if you're carrying less speed, then you just need to brake like that, but for a shorter distance. That's not the case. Generally, what we do, instead of braking hard, but at a shorter distance, we actually brake a little bit earlier, but we brake less. So we already start building the arc.

We actually have this, and then this. Of course, there are some variations here and there, but I just want to tell you that it is possible in many corners that it will not break hard. You don't need to reach peak deceleration in that corner specifically, you can just break a little bit less, and already start turning a little bit here, and you're just right away from the beginning managing that proportion.

Managing the Proportion of Braking vs. Rotation

Right here, you have, say, 50% braking, 50% rotation. And right here, you have 10% braking and 90% rotation. So you're consistently dealing with these proportions of braking versus rotation, and they're always going to happen whether you want it or not. And I keep repeating that because it is important.

In case you are doing this kind of braking, where you're not breaking 100% right away, because you're already turning to the corner, this will only work if you already have some kind of steering right away from the beginning. So if you start breaking a low pressure right here, but you're only adding steering like late, for this duration here, you are actually under the limit. So be careful with that.

This kind of braking trace that I just showed you, like breaking less only works if you're already starting to do some turning so that you can always combine that rotation versus deceleration and adding up to a total of 100% grip usage.

The Confusing Part: You're Always Releasing Brakes

You know, the most confusing thing to explain, to even understand, to try it yourself, is the fact that whenever you're explaining that when you add brakes, you get more rotation, you hear add brakes as if you're getting more brakes while turning. Even in the exercise I just showed you, I'm turning, I add brakes and the car points more.

But the problem is that we're never adding brakes into a corner. We're only releasing, right? So this is the confusing part. You're releasing the brakes from a higher pressure, but still keeping that pressure that maintains the rotation function. So you are releasing the brakes at that pressure that feels as if you're adding brakes and getting rotation. So that's why it's confusing.

You're always releasing. You're not going to release the brakes and then add more brakes Bitcoin and to get rotation. Do not do that. You're just releasing more slowly. So you already have that weight on the front tires. You already have that weight on the front tires, helping the car turn more from a higher pressure, not adding pressure mid-corner.