Trail Braking in a Kart: KZ, Senior, Junior and Mini

By Alessio Lorandi, 2013 CIK-FIA World Champion, KF-Junior. What is in here comes from my own driving, in single speed karts and in KZ, and from the data I look at with the drivers I coach.

“Where should he hold the brakes? Until the apex?”

Parents ask me this all the time. And my answer is always the same. It depends.

It depends on the corner, and it depends on the kart. A KZ with front brakes and a 60 Mini don’t trail the brakes in the same way. So here I go class by class. And I tell you from the beginning that trailing the brakes is more an art than a science.

What is trail braking in a kart?

Trail braking is when you hold the brakes not only in a straight line, but also when you start turning in.

Why do you need it? Because in a heavy braking zone, turning the steering wheel alone doesn’t slow you down enough. So you keep the brakes on while you turn. I also call it combined braking. You brake and you turn together. And normally, the more combined you are, the faster you are.

What happens to the kart? The weight shifts forward. The front lowers down and the rear unloads, so you get more rotation. It also creates flex on the kart, and that helps to lift the inside rear wheel.

But listen. Rotation is good, but it’s not really the priority. A kart has a fixed rear axle and no differential, so you rarely have too much rotation anyway. The real point is another one. If you hold the brakes until the apex, you can brake later. That’s where the lap time is.

By the way, if the first hit on the pedal is weak there is nothing to trail, so I wrote a separate page on threshold braking in a kart.

Where do you hold the brakes until?

I have a rule of thumb, and it’s the same for every class. It goes by the speed of the corner.

So you don’t trail brake everywhere. In the whole lap it’s maybe three, four corners.

And “until the apex” is a rough estimate. Normally you go on the throttle at the apex, or one, two meters before. I can’t recall a corner where I go on the throttle after the apex, unless I overshot it. So in a corner with a long straight after it, you hold the brakes until two, three, four meters before the apex.

When do you go on the gas? When the kart has completed the rotation. And that is mostly a bit before the apex.

If you come off the brakes much earlier than that, you’re probably not braking late enough. How braking zones change by type of corner is in my go kart braking tips, so I don’t repeat it here.

Why can’t I tell you the exact point to come off the brakes?

Because I don’t know it myself.

The release of the brakes happens in a fraction of a second. 0.1, 0.2 seconds, who knows. It’s not something you’re aware of. If you ask me “how are you releasing the brakes?”, my answer is “I don’t know, I’m just doing it”.

I could tell you “as soon as the rear wheel lifts, come off the brakes”. But I would be making it up.

So I can’t tell you “off the gas at 637 meters”. I can’t tell you “off the brakes four meters before the apex” or “wait 1.3 seconds”. And I don’t want kids to become robots who come off the brakes two meters before the apex “because Alessio said so”. Even the meters I gave you above are only there to explain the idea.

You have to feel it. And you have to adapt it to the session, to the track and to the setup you have that day.

How do you trail brake in a KZ or shifter kart?

The shifter is the kart that trails the most. And the reason is simple. A KZ has front and rear brakes. Single speed karts today don’t have front brakes.

By the way, I drove with front brakes until 2014, in KF2. You had a lever on the right of the steering wheel for the fronts. It was really cool, because the kart was light and you could really brake into the corner.

On a shifter you normally run something like a 60 40 brake bias towards the front, or even 65 35. Why so much front? Because if the rears lock, the kart gets unstable. And it’s rare to lock the fronts, unless the grip is very low. To me it happened in the wet and on a formation lap.

So how do you drive it? In the hairpins you do a V line. A V in the shape, and a V in the speed. You brake really late and you stop the kart more in the mid corner than a single speed kart does. Then you exit tighter, because you have the gears and the torque to pull you out.

And there’s a reason for the V. To take advantage of the front brakes you need to be straight with the steering. So you arrive nice and wide, and then you point the apex and go in a diagonal direction, not in a round one.

You hold the brakes pretty much until the apex. Not past the apex, that would be silly, because right at the apex you want to be on the throttle. So the transition from off the brakes to on the gas has to be really, really fast. And holding the brakes until the end keeps the load on the front, so the kart rotates fast and you can straighten up for the exit.

How hard can a KZ brake? At the World Championship in Franciacorta I was pulling 1.8, 1.9 G under braking for turn 5 and for turn 13, the last hairpin. With low grip it’s more like 1.6, 1.7.

In a shifter you also have the engine brake when you downshift. I like to use it quite a lot, because it lets you brake one or two meters later. But if you’re too aggressive, you stress the engine and you lock the rears. More on that in my shifter kart driving tips.

One more thing. You do the V only in the slow corners. In the fast corners a KZ drives like a single speed kart. In the medium corners too, you open up the entries. And even in the hairpins, don’t overdo it. You still want to carry quite a bit of minimum speed.

How do you trail brake in a Mini, junior or senior kart?

Seniors, juniors and 60 Mini are a different animal. Here it’s all about momentum.

What does that change? You come off the brakes just a touch earlier. You trail a touch less than a shifter. And I’m talking about a very, very little difference. I can’t tell you in advance how much. It has to be felt.

The mistake I see is the opposite one. A driver gains one meter on the brakes and then loses minimum speed. That’s a bad trade in a single speed kart. In a 60 Mini you have 10 horsepower. If you gain a little on the entry and then the RPMs are dead in the middle of the corner, you lose much more on the exit.

And on the data you see it straight away. When you overslow, the speed trace has a V shape. For a Mini, a junior or a senior that is bad. You want to go from a V to a U, by opening up your entries and your exits.

So does that mean slow in, fast out? No. I hate that technique. The goal is fast in, fast out. I explain why in 3 reasons why I hate slow in fast out.

When I say “stop the kart” to a single speed driver, I mean make the apex. I don’t mean stop in speed like a KZ does. You still brake as late and as hard as you can. You just don’t kill the minimum speed doing it.

What does a tight line cost you in each class?

Put a senior OK and a KZ on the same track, like Lonato, and look at the data.

The KZ brakes a lot later. But it loses in the mid corner. The senior is lighter, its lines are more open, and it carries a lot more speed at the apex. So the KZ needs to gain on the entry. If it doesn’t gain on the brakes, it can end up slower than the senior, even if on paper it’s the faster kart. And the more braking spots a track has, the more the KZ gains.

Now think about what happens when you defend or you overtake. You make a tight entry, or a tight exit. Basically you do a V line.

A KZ doesn’t really lose much when it defends a corner properly. It has the gears and the brakes to take advantage of that line. A junior, a senior or a Mini doesn’t. They kill the momentum, and they may lose three, four tenths, or even half a second.

That’s why in a single speed kart you never drive a V line in a qualifying lap. It would be silly.

What happens if you come off the brakes as soon as you turn in?

This is the common mistake. The driver brakes in a straight line, and as soon as he turns the steering, he comes off the brakes.

What happens then? You unload the front. The weight goes back on the rear, and you get understeer. And then you wait. You coast.

Coasting is the opposite of trail braking. You’re not on the brakes and you’re not on the gas. In a slow corner that you arrive at with high speed, you don’t want that. In a KZ even more. There the goal is a stop and go, not a coast where you carry the speed in the mid corner and pay for it on the entry.

And coasting doesn’t put temperature in the tyres. You’re just massaging them. I want you to be a “braking monster and not a coasting kitten”.

Coming off the brakes too early almost always starts from braking too early. If that’s you, read how to fix your braking technique first. And how hard you slow down in the first part of the braking is a different topic. I call it deceleration efficiency.

When should you trail brake less?

There are corners where holding the brakes until the apex is too much.

The first one is a banked corner. The banking holds the kart for you, so you can come off the brakes earlier. In Formula 3, at turn one in Zandvoort, the banking lets you come off a couple of meters earlier.

The second one is a double apex. There you may have a moment where you roll.

Then the medium speed corners. If you trail too much there, you stop the kart too much. And the fast ones, where you don’t trail at all.

That’s why I do track walks, and why I talk about the “corner DNA”. Every corner asks for something different. 90% of the times, in a heavy braking zone, you brake really late and you hold the brakes pretty much until the apex. But you have to know which corners are the other 10%.

Can trail braking fix understeer or oversteer?

Yes. The brakes are a tool, and you can use them to change the balance of the kart without touching the setup.

If you have understeer on the entry, trail more. You load the front, you carry more entry speed and you get really good rotation. And if you were braking at 80% of your capacity, get to 100%.

There’s one exception. If you’re already oversaturating the front tyres, more load doesn’t help. In that case you may have to come off the brakes a bit earlier.

If you have oversteer, do the opposite. Trail a touch less. The front raises back up, the rear picks up some load, and you get more stability.

That’s how two drivers can do the same lap time with two different setups. The whole picture is in understeer vs oversteer.

Is trail braking in a kart the same as in a car?

The idea is the same. The amount is different.

In a kart you feel the weight going forward less than in a car. But it’s there. I felt it with my KZ. Sometimes I had a very low front bumper, and when I braked hard I could feel the bumper touching the ground.

In a car it’s multiplied. More weight, more speed, more downforce. In 2015, my first year in Formula 3, my engineer showed me on the data that in the two hairpins at Hockenheim you have to hold the brakes all the way until the apex, or you lose the front. And I was doing a tiny bit of coasting in the middle of the corner. It’s a very common mistake for drivers who come from karts. When I tried it, the car felt much more pitched on the front and it rotated way more.

So why the coasting? Because in a kart you normally come off the brakes slightly before the apex, and you leave a very small transition before the gas. A kart has an axle, not a differential and suspensions. You want the kart to complete the rotation on three wheels before you go on the throttle. If you go too early, you get understeer.

That’s also why a shifter is a good step before single seaters. You get used to the gears and to the front brakes. Then in cars you learn trail braking really deeply.

How do you see trail braking on the data?

You look at the overlap between the brake and the lateral G. If you’re still braking while the lateral G is building up, you’re trailing. On Purpl there’s a specific trail braking channel for this.

It’s also what the friction circle tells you. The tyres are meant to trail brake.

Then you compare. Say your team mate is a bit faster in one corner. You open the data and you can find three different things:

• He holds the brakes a little bit longer than you. So you can brake later, hold more, and get the same exit.
• You’re already braking too late and trailing too much, and you can’t stop for the apex. So you brake more efficiently, or you bring the braking a bit earlier to get a better exit.
• You brake in the right place, but you stop the kart too much, because you trail too much in a medium speed corner.

If you don’t have a team mate, compare against yourself. Session against session.

One thing the data shows very clearly is a foot resting on the throttle while you brake. I wrote about it in the common mistake of holding some throttle under braking. The other articles on reading data are in the karting telemetry guides.

How do you learn to trail brake?

By pushing the braking point. Nobody can teach it to you with words.

If you brake super late, you’re forced to hold the brakes. It’s the only option you have not to miss the corner. That’s how you end up trailing. You should feel that you must hold them until the end or you go straight.

I call it “exposure therapy”. You brake later and later. You’ll make mistakes. You’ll spin. You’ll put a wheel on the grass. That’s fine. With time it becomes subconscious, and you stop thinking about it.

And don’t feel bad if a young kid isn’t there yet. Kids of four or five at the summer camps just lift, with no brakes at all. It comes with the laps.

Next time you’re at the track, pick the slowest corner that comes after a long straight. Brake a bit later every lap, and see what your foot does when the apex is coming and the kart is not stopped yet.

Frequently asked questions

What is trail braking in karting?

It’s holding the brakes not only in a straight line, but also when you start turning in. You brake and you turn together. It keeps the front loaded for rotation, and above all it lets you brake later.

Do you trail brake in every corner?

No. In the whole lap it’s maybe three, four corners, the slow ones you arrive at with high speed. In a medium speed corner you come off quite a bit before the apex. In a fast corner you don’t trail at all.

Do you hold the brakes until the apex in a kart?

Pretty much, in a slow corner after a long straight. But “until the apex” is a rough estimate. Normally you’re on the throttle at the apex or one, two meters before, so you’re off the brakes slightly before the apex. Never past it.

Is trail braking different in a KZ?

Yes. A KZ has front and rear brakes, so it trails the most. You brake really late, you V the line in the hairpins and you hold the brakes pretty much until the apex. In a single speed kart you come off a touch earlier, to keep the momentum.

Should you trail brake more if the kart understeers?

Normally yes. Trailing more loads the front and gives you rotation. If you’re already oversaturating the front tyres, come off a bit earlier. With oversteer, trail a touch less so the rear picks up load.