Highside Crashes: Understanding and Preventing Rider-Induced Highside Crashes

written by David Mixson

LOWSIDES AND HIGHSIDES, FEATURED ARTICLES

While this article focuses on highside crashes, understanding lowside crashes is just as important because they’re related. Be sure to read Lowside Crashes: Understanding and Preventing Rider-Induced Lowside Crashes before reading this. Understanding lowsides and highsides is a package deal—in part because a lowside and a highside start out the same.

I’ve spent hours going through slow-motion videos trying to understand the physics of a highside, and this is what I’ve discovered.

I have to warn you. What you’re about to learn is both fascinating and terrifying. The physics of a highside is fascinating! The thought of doing a highside is terrifying!

What Is a Highside Crash?

A highside crash is when your motorcycle loses stability control and catapults you over the handlebars. You eventually hit the ground, often headfirst, and your bike tumbles toward you. Figure 1 (below) shows a rider in the middle of a highside.

Figure 1 Highside Crash

(Motorcycle Launches Rider)

Yeah, I know. Freaking scary, right?

Executive Summary

Nearly all highside crashes are rider-induced crashes triggered when a rider locks up his rear tire (by over-braking), or spins his rear tire (by over-accelerating)—and then allows the rear tire to rotate normally again before the motorcycle starts sliding on the ground (by releasing the rear brake or backing off the throttle). In other words, a highside occurs when a lowside is triggered but not allowed to finish.

And just like with lowsides—the ONLY way to prevent a highside from happening is to ride a motorcycle equipped with an anti-lock braking system (ABS) and Electronic Stability Control (ESC). I’ll go into more details below (and in other articles), but I wanted to make that point as quickly as possible so someone can’t miss it.

In Figure 2 (below) the skidding rear tire has moved out of alignment with the front. If the rider releases the rear brake (or backs off the throttle) and allows the tire to rotate again, he will most likely highside.

Figure 2 Highside Crash

(The Beginning of a Lowside or Highside)

The Physics of Why

A highside occurs when a skidding (or spinning) rear tire that has slid out of alignment with the front tire is allowed to rotate normally again (by releasing the brake or backing off the throttle).

When the skidding rear tire (which is now no longer tracking behind the front tire) is allowed to rotate normally again, it immediately wants to track in line behind the front tire. When this happens, the bike instantly sits up to a vertical position.

Since the motorcycle was leaned over (squatted) because the rear tire was sliding, the motion of the motorcycle snapping to a vertical position is like releasing a coiled-up spring. This combination launches the rider.

I know this is a difficult concept to understand. It’s also a hard one to explain. I must be on my hundredth edit of this section. Stay with me. I have real examples below that will help.

A Frame-by-Frame Analysis

The illustrations below are from a real highside crash captured on video.

In Figure 3 (below), both tires are in strong rotational contact with the ground. Everything is working as it should.

Figure 3 All Good

(Riding Around a Curve Just Fine)

In Figure 4 (below), the rider locks up his rear tire and skids (or over-accelerates and spins rear tire) while he’s in the curve, and his rear tire loses rotational contact with the pavement. This is the beginning of a highside. It’s also the beginning of a lowside. What happens next determines whether it finishes as a lowside or a highside.

Figure 4 Beginning of a Highside

(Rear Tire Loses Traction)

In Figure 5 (below), the rear tire has been allowed to rotate again (by releasing the rear brake or backing off the throttle), and the bike has snapped up into a vertical position. This motion catapults the rider.

Figure 5 Highside Continues

(Bike Launches Rider)

In Figure 6 (below), the fun continues. The rider flies over the handlebars, and his bike keeps going.

Figure 6 Highside Continues

(Rider Continues in Air)

In Figure 7 (below), the rider lands, and his bike continues in a different direction—which is not always the case.

Figure 7 Highside Complete

(Rider Lands)

What Triggers Most Highsides?

Now that we know what a highside is let’s take a look at what triggers them.

NOTE: Before we go any further, it’s worth noting that a skidding tire (which has kinetic friction) has less grip than a rolling tire (which has static friction). This explains why the rear tire slides around to the path of least resistance when the rear tire loses static friction (skids/spins).

Highside Trigger #1

Locking up rear tire (and then releasing it) while in a curve.

If you lock up (skid) your rear tire (by over-braking) while going around a curve, then release the rear brake and allow the tire to rotate again, you’ll most likely highside.

Highside Trigger #2

Spinning rear tire (and then backing off throttle) while in a curve.

If you spin your rear tire (by over-accelerating) when going around a curve, then back off the throttle and allow the tire to regain traction, you’ll most likely highside.

Less Common Triggers

I explained an additional trigger in Motorcycle Smarts. It’s less common, so I’ll only mention them here: (1) locking up rear tire (and then releasing it) while going straight.

I’ll make this point one more time.

Nearly all highside crashes are rider-induced crashes triggered when a rider locks up or spins his rear tire—and then allows it to rotate normally again before the motorcycle lowsides. And the ONLY way to prevent your rear tire from locking up or spinning is to ride a motorcycle equipped with ABS and ESC.

The Real Dilemma

Here’s something to consider. Once your back tire starts skidding (by over-braking), or spinning (by over-accelerating), one of two things is likely to happen: You’ll either LOWSIDE or HIGHSIDE. I’m getting depressed thinking about my options. While I have your attention, let me say it (again) because it’s one of the most important points that I never see mentioned in the motorcycle mega books from the past.

Real Highside Crashes Captured on Video

I’ve watched lots of videos on YouTube that showed riders highside-crashing alone. In the videos below, none of the riders were seriously injured, but due to the nature of highside crashes, some might find them uncomfortable to watch. On second thought, maybe riders should be required to watch some of these crashes before getting their license.

Note: Keep watching past the initial crash scene. Ken shows each one in slow motion part-way through each video. Those are really interesting.

Highside Crash: Illustration One

In the video below, the rider spun his rear tire accelerating out of the curve, and then backed off the throttle before he lowsided. When this happened, the rear time snapped back in line with the front tire, and he highsided. If his motorcycle had ESC, the system would have kept him from spinning his rear tire—regardless of how hard he twisted the throttle.

In other words, ESC would have prevented this highside crash.

Highside Crash: Illustration Two

In the video below, the rider spun his rear tire accelerating out of the curve, and then backed off the throttle. When this happened, the rear time snapped back in line with the front tire, and he highsided. If his motorcycle had ESC, the system would have kept him from spinning his rear tire—regardless of how hard he twisted the throttle.

In other words, ESC would have prevented this highside crash.

QUICK TIP: The faster you’re going when you lock up your rear tire (and the farther out the skidding rear tire gets while it’s locked up), the more abruptly the highside snap will be once the tire is allowed to rotate again. If you’re going slowly when you trigger a highside, it might not have enough energy to throw you off your bike. If you’re going at race-speeds, you’ll be tossed off in an instant. See next video.

Highside Crash: Illustration Three

In the video below, the rider was going 112 mph when he highsided. Wow, what a launch!

The MotoGP racing organization doesn’t allow motorcycles to have ABS, but they do allow them to have Traction Control. Traction Control is a simplified version of ESC and should have been enough to keep the rider from spinning his tire by over-accelerating, which appears to be what happened.

I watched an interview with the rider and he said the electronics package (I’m assuming he’s talking about Traction Control) should have helped him keep from spinning his rear tire, but that it didn’t. “We’ll have to figure out what’s going on with that.”

If you’d like to see some different camera angles of this crash, including one from a camera mounted on the seat behind the rider, you can see them on YouTube here.

Highside Crash: Illustration Four

The video below is a little troubling to watch, but the rider wasn’t seriously hurt, and it shows the transition from a lowside to a highside so clearly, that I decided to include it.

The slow-motion portion of the video shows the rear tire skidding. If the rider had kept his rear tire locked up, he would have lowsided.

But right before his back end came around in a lowside, he released the rear brake, and the tire started rolling again. The instant this happened, the rear tire snapped back in line with the front tire, and he highsided. Since the rider wasn’t going very fast, it wasn’t violent like it was with the MotoGP rider.

If his motorcycle had ABS, the system would have kept him from locking up his rear tire—regardless of how hard he applied his brakes.

In other words, ABS and tightening his turn using countersteering would have prevented this crash.

Highside Crash: Illustration Five

In the video below, the rider highsided. You be the judge of whether he released a skidding rear tire by backing off his brake, or he stopped a spinning rear tire by backing off the throttle. The beauty is that it doesn’t really matter which one happened. ABS would have kept him from skidding his rear tire in the first place, and ESC would have kept him from spinning it.

In other words, ABS and ESC would have prevented this highside crash.

ABS and ESC could have prevented all the highside crashes above.

That’s why ABS and ESC should be Federally mandated for on-street motorcycles sold in the U.S.

NOTE: Traction Control is an electronic component that’s a simplified version of Electronic Stability Control. I explain ABS, ESC, and Traction Control here.

On a personal note, I’d like to thank Ken Snyder for the videos I used above. I scoured hundreds (maybe thousands) of crash videos on YouTube to show lowside and highside crashes, and his videos are the best. You can find all of his videos here.

NOTE: I’ve never (knowingly) watched a video on YouTube that shows a rider being seriously injured or killed. That does me no good, and I think it’s disrespectful to the rider and their family. But YouTube can be a great tool if used properly—because there’s usually a lesson buried in every motorcycle crash.

* This article has excerpts from my books Motorcycle Smarts and Motorcycle Hacks.