Big Lies #1: in slow, out fast

This is post #1 in a series of articles about some of the biggest lies in high performance driving. Where to start? How about the one you’ve heard 100 times: in slow, out fast.

So what’s the big lie exactly? That “in slow, out fast” is the proper way to drive a corner. Of course you have to slow down before a corner, but exactly how slow is slow? Given the way most HPDE drivers navigate a track, slow is way too fucking slow. The problem with the phrase is that it makes one think that mashing the brake and throttle is a fast way around a track.

As driving coaches, we say “in slow, out fast” for our own personal safety, not because we want the student to be fast. I don’t get paid enough to risk my life for a day of someone else’s thrills. You think I want to get into a 500 hp car with a novice behind the wheel? No, no I don’t. So me and every other coach says “in slow, out fast” and pray that we survive the day.

Hitchen’s Razor

I made this infographic/meme as part of my Pandemic Memes. On here you’ll find Hitchen’s Razor.

Next time someone says something provocative, ask them to show you the data. For example, let’s say you’re reading a blog about high performance driving and the author says “in slow, out fast is a big fat lie”. Ask the author to show you the data. Some statements may be made by experts with decades of experience. Other statements aren’t meant to inform you, but to con or troll you. Ask to see the data. Here, I’ll take the lead. “Hey Ian, if you’re going to say in slow, out fast is a big lie, why don’t you show some data?”

Data

In the following graph, you will see two speed traces. On the Y-axis is the speed of the vehicle. On the X-axis is the distance the vehicle has traveled. The graph is synchronized on distance so each point along the X-axis is the same part of the track. What do you notice here?

• The driver on the blue line is going in slow and out fast
• The driver on the red line appears to be afraid to brake
• The minimum corner speeds of the red line are a little higher than the blue line
• The maximum straight speeds of the blue line are much higher than the red line

So which driver is lapping faster? It turns out that they are only 0.183 seconds apart over a ~1.5 minute lap time. The driver on the red line (my twin brother Mario) was doing a 3rd-gear-no-brakes drill. Yes, that’s right, he wasn’t using his brakes at all. And yet he’s doing the same lap time as the driver furiously mashing pedals on the blue line. Looking at the graph, would you be able to predict this? Not unless you have some experience reading speed traces. The high speed differences look like a big deal. But it turns out that going slow for any length of time will really kill your lap time.

In fast, out slow

You know why nobody ever says “in fast, out slow”? Because it’s fucking terrible advice. It’s dangerous and slow. So by contrast, “in slow, out fast” must be great advice, right? Despite being catchy, and having some nicely contrasting words, no, it isn’t good advice if you want to improve as a driver.

Cornering faster

So what would I tell a student who wanted to improve and wasn’t threatening my life? It depends on the skill and experience of the driver.

For lower intermediate drivers, I would focus on minimum corner speed. Your minimum corner speed defines pretty much your entire cornering strategy. How slow do you plan on going and where exactly is that spot of minimum speed? I call the position of minimum speed the nadir. Everything before the nadir is slowing down and tightening. Everything after the nadir is speeding up and opening. In a typical corner, the nadir is before the apex. To summarize this in one punchy statement I offer this: don’t go any slower than the slowest point in the corner.

For higher intermediate drivers, I would focus on rotating the car. If the car isn’t slipping on the way into the corner you probably went in too slow. If you never have to make steering corrections, you’re not driving hard enough. And by hard I don’t mean hitting the brake pedal hard, but quite the opposite. Oversteer is generated with a soft brake pedal. A gradual release increases oversteer. To be clear, the oversteer you’re generating is on the way into the corner, not on the way out. Here’s my phrase to remember these things: slip not, win not.

Appendix

Here’s the graph with the time delta at the bottom. Remember, always demand the data.

4 thoughts on “Big Lies #1: in slow, out fast”

1. Sean says:

I like “in fast out fast” best. I recognize that focusing only on being the latest braker is a common flaw. I try various approaches and let the data decide.

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2. thekornfeld says:

I don’t know if you’ll see this since this is an old post, but:

I was just sharing a setup in iracing with a few people and explaining how to use it, and had a mini epiphany.

I was basically telling them that this setup required significant trail braking, without using that specific term. And one of them responded by saying, “Yeah, of course, “slow in, fast out.”

And I was trying to explain how trail braking works, when it hit me, that that saying is actually *almost* correct. It’s just that it shouldn’t be, “slow in,” it should be, “slow*ing* in.”

As in, you have to be going fast enough that you need to be slowing the entire way into the turn. If you aren’t going fast enough to require slowing all the way in, then you aren’t going fast enough. And if you’re going so fast that even when you *are* slowing, you can’t get down to the apex, then you were going too fast.

Obviously, and as always, there are tons of exceptions to this, (e.g., fast turns where you may just breathe out of the gas to get it to turn in and quickly go back full throttle).

But personally, I think this saying is just as catchy, and a whole lot more informative. Thoughts?

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1. I like it because “slowing” feels dynamic rather than “slow” which feels static. Sadly, I don’t think anything can replace “in slow, out fast” because it’s just too common. But that shouldn’t stop us from trying.

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