Dynamics of a High side and Low Side crash.

[afinepoint]

I have been studying video and am trying to understand the physical dynamics of these two crashes. How they happen, how to avoid them and can you save yourself once one begins?

It seems in studying the low side crash either the rider leans so far as to move the tread from beneath the bike or one or both tires loose traction ( for whatever reason) at lean and the motorcycle simply “slides away”. Simple to see and understand. Do I have it right?

The High side is more complicated. Slowing down the videos it appears that the rear tire looses traction and regains it milliseconds later enough to pitch the rider forward. Correct? Why does this occur? I saw the 4/7 post of Kbacon but there wasn't a detailed discussion.

I have analyzed videos of professional riders and they seem to put the cycle in the same slide into and around corners without upsetting the machine. The front and rear tires are out of alignment the same as the guy who’s getting ready to crash yet the pros gracefully slide around the bend and exit under power. Are they keeping the rear spinning faster than the front until the bike straightens?

Repeating my above question can you save yourself once the rear tires steps out? In a video my daughter took this July 3rd at VIR South a rider coming out of turn 6 did something to get out of alignment, the bike does a big wiggle but straightens and continues.

http://s458.photobucket.com/albums/qq301/afinepoint/?action=view&current=VIRbikeskid.mp4

My curiosity is more than an idle one. No rider wants to experience these events. To avoid them I need to understand them and if one happens it would be great know how to remain vertical.

Reg

 

[ronhix]

To put it simply, you will probably not "save" either a "low side" or "high side" once they start to happen. I've crashed with both and saved both, when I saved them (much like the rider in your video) I think it was just luck to be honest cause they happen too fast to really have a chance to intelligently react to them. The more seat time and experience you have, the more you will be able to instinctively react to things, but there is no real time to think, decide and then react. Sure, I have saved a few low sides on my knee but it was just because I was lucky to have my knee in the right place at the right time!

Therefore, the best path is the one that will prevent you from getting into these situations. Focus on HOW EXACTLY to ride a bike safely and skillfully. Focus on how to use your body, the brakes, the throttle, the race line, etc. to get the most out of the bike with the least amount of risk.

As you probably already know, the NESBA CR's are constantly working with the members on the skills necessary to be a faster, smoother, safer and more skilled rider. This is the best place to focus because it will go a long way toward preventing these two issues.

 

[greeny]

technically speaking, when that rear tire starts to swing out, the best thing to do is nothing. staying on the throttle will allow the tire to continue to spin which will either result in a sick photo and a nice big blackie or a lowside from the rear coming all the way out and around the front. both of those situations are much better than the alternative - which is letting off the gas and allowing the rear tire to regain traction. this is why you see such violent highsides... the tire is regaining traction.

however, as ron said, it's all instinct. the best way to save yourself from these situations is to not get in them in the first place. it's more important that you understand being smooth on the throttle out a corner is the best way to control these types crashes.

 

[afinepoint]

ronhix;142520 wrote:
Therefore, the best path is the one that will prevent you from getting into these situations. Focus on HOW EXACTLY to ride a bike safely and skillfully. Focus on how to use your body, the brakes, the throttle . . .
That's why I joined and do track days.

greeny;142526 wrote: technically speaking, when that rear tire starts to swing out, the best thing to do is nothing. staying on the throttle will allow the tire to continue to spin . . .

Is this what the pros do when they appear to be "drifting" through a corner?

greeny;142526 wrote: it's more important that you understand being smooth on the throttle out a corner is the best way to control these types crashes.

I try to keep tension on the chain throughout the turn adding a small amount more throttle after the apex and more as the bike exits.

Reg

 

[ronhix]

afinepoint;142531 wrote: That's why I joined and do track days.

Reg

And you sir are the reason NESBA exists.

:cheers:

 

[fitz]

afinepoint;142531 wrote:

I try to keep tension on the chain throughout the turn adding a small amount more throttle after the apex and more as the bike exits.

Reg

You actually think about that as you are going through a turn, chain tension?

Reg, has anyone accused you of over thinking something?

As a simple beginner myself the best advice I can give you is think about being smooth, smooth, smooth, and look where you want to go, try not to get caught up in over thinking every movement or you will find yourself without much left to think about what SHOULD be doing.

fitz

 

[afinepoint]

fitz;142547 wrote: You actually think about that as you are going through a turn, chain tension?
Yes I do among other things like smoothness, traction, speed, lean, RPM, power band, hand, foot and body position . . .

fitz;142547 wrote: Reg, has anyone accused you of over thinking something?

Funny you should ask. Yes, more than once. I anaylyze things. It's what I do and how I'm wired. Oh I'm also a perfectionist.

Reg

 

[Steve]

Is this what the pros do when they appear to be "drifting" through a corner?

IMHO, short answer: yes, longer answer: It's more a matter of how much faster they have the rear spinning than the bike is going. If you spin the rear too much, you'll lowside with the rear tire losing traction, otherwise, you'll do a nice power slide out of the turn. Like Ron and Jordan alluded to, it's not a technique recommended for trackday riding.

 

[ninjamansc]

Keep in mind that most of the pros have some fancy-shmancy traction control electronics that will keep the RPMs from climbing too rapidly, thus making it easier to maintain the slide. Heck, motoGP guys have GPS based trac control that will change it's intervention based on which corner they're in.

As for dynamics of a highside, the rear breaks loose, then regrips causing a very high load on the rear shock. Moments later, the shock unloads, catapulting rider/bike. Like in motocross. It's the loading/unloading of the shock that provides the majority of air time, not necessarily speed.

 

[fitz]

afinepoint;142559 wrote: Yes I do among other things like smoothness, traction, speed, lean, RPM, power band, hand, foot and body position . . .

Reg

Reg, if you have time to think about all that stuff you're not going fast enough.

In my previous post I don't think I explained myself well.

I would sugest you read "A Twist of the Wrist" I or II by Keith Code. There he talks about "Your $10 bill" The idea that everyone has just so much attention (like money) to spend on the actions of riding has not changed. If you start out with $10 in your pocket and spend it all, you are broke and having no money causes its own kind of panic. Having no attention left to perform the needed actions while riding always creates some panic.

Reg, I analyze the crap out of things too, mainly people (it's what I have a degree in) and you apear to be trying to analyze every detail of riding on the track in order to prevent an accident. Nothing wrong with that, off the track, on the track it can create it's own set of problems.

I hope to some small degree I explained myself a little better.

fitz

 

[afinepoint]

fitz;142694 wrote: Reg, if you have time to think about all that stuff you're not going fast enough.
I know. I'm working on it. With worry about dropping my (street) bike, riding inexperience and weight of the VFR I am not carrying enough speed into and through the turn. Nor can I accelerate as fast as I want down the straight.

fitz;142694 wrote: I hope to some small degree I explained myself a little better.

fitz

You have. Thanks.

Reg

 

[afinepoint]

ninjamansc;142614 wrote: Keep in mind that most of the pros have some fancy-shmancy traction control electronics that will keep the RPMs from climbing too rapidly, thus making it easier to maintain the slide. Heck, motoGP guys have GPS based trac control that will change it's intervention based on which corner they're in.
I didn't know this. Here's a video of the best motorcycle control I have ever seen. Even more impressive since he's on a wet track.

http://www.youtube.com/watch?v=KycZk1M7g24


ninjamansc;142614 wrote: As for dynamics of a highside, the rear breaks loose, then regrips causing a very high load on the rear shock. Moments later, the shock unloads, catapulting rider/bike. Like in motocross. It's the loading/unloading of the shock that provides the majority of air time, not necessarily speed.

Thanks Ninja. This is the type of technical information I am looking for.

 

[daddyfriedrich]

Watch closely

Look at the following gif closely. Sometimes a highside occurs without loading/unloading. The traction quotient involves latitudinal and longitudinal components. This gentlemen encountered a situation where the spin of his rear wheel was dropping his lat. friction, and he started to slide (step out). He gets to a point of angular attack where the spinning of the tire no longer allows the tire to slide. At that moment, it is as if the tires hit a curb - flipping the bike over onto it's right side, catapulting the pilot (Poor Dan, he really flew!)

http://www.1000rr.net/forums/showpost.php?p=1776716&postcount=9

 

[D-Zum]

A CR a LONG time ago said to me that riding a motorcycle was an exercise in traction management.

Want a great way to explore the limits of a motorcycle's traction limits and how it reacts when those limits are exceeded? Get a small displacement dirt bike and a big open field. Make yourself a big oval "track" and spend some time leaned over through the corners of the oval gradually feeding more and more throttle until you feel the back end break loose. If you wipe out..no big deal. You're in the dirt. Get up..dust yourself off and keep doing it until you can confidently predict and react to what the bike's going to do when it gets the wheels out of line.

Comfortable with it going clockwise? Now work it counter-clockwise exploring the limits of tractio

My CRF150's about to start getting a workout on Saturdays.

 

[daddyfriedrich]

Hellz yes. I never rode dirt, still haven't, and I know my riding suffers. It definitely works for the Kentucky Kid!

 

[punkass]

D-Zum;159378 wrote: A CR a LONG time ago said to me that riding a motorcycle was an exercise in traction management.

Want a great way to explore the limits of a motorcycle's traction limits and how it reacts when those limits are exceeded? Get a small displacement dirt bike and a big open field. Make yourself a big oval "track" and spend some time leaned over through the corners of the oval gradually feeding more and more throttle until you feel the back end break loose. If you wipe out..no big deal. You're in the dirt. Get up..dust yourself off and keep doing it until you can confidently predict and react to what the bike's going to do when it gets the wheels out of line.

Comfortable with it going clockwise? Now work it counter-clockwise exploring the limits of tractio

My CRF150's about to start getting a workout on Saturdays.

when you get bored of that. Same little dirt bike but replace the rear tire with a slick and ride around on some grass!

 

[thumpin250]

I came off dirt racing to the pavement and did just what he suggested with my 450. Eventually in a nice bean field you'll be draging your hand along as you drift and spin your balls off......soooooo much fun

 

[ZeroBahamutxRR]

greeny;142526 wrote: the best way to save yourself from these situations is to not get in them in the first place. it's more important that you understand being smooth on the throttle out a corner is the best way to control these types crashes.

I can't agree more. I had a high side save at Tbolt last year and was just lucky. When I got back on the throttle I was too abrupt with it. Being smooth cannot be stressed enough.

 

[DvlsAdvc8]

On the tire coming out, I gotta say a couple wet TDs gave me awesome lessons. My first two TDs ever were in the rain: VIR and then Barber.

It really makes you focus on being smooth rather than getting on the throttle hard/soon and braking hard. As the second day (Barber) went on, I was getting consistently loose coming out of T5 - with a couple good twitches out - a pucker at first, but controllable and really helped my confidence in having the bike moving/squirming under me - as you get under braking with the rear feeling light and squirmy. You get to where you don't mind the movement and that comfort overrides the instinct to react and really cause a problem.

Its the seemingly inexplicable lowsides that still affect my confidence level. I lowsided at VIR T1 once, and while I'm sure there are a million things I could have done better, I just ended up with this feeling that the bike just ... went away ... with out much of a triggering action or anything specific to pin it to. Leaves you with this lingering "is it gonna stick" doubt that I still have to push out of my head.

 

[bcrunk11]

ninjamansc;142614 wrote: Keep in mind that most of the pros have some fancy-shmancy traction control electronics that will keep the RPMs from climbing too rapidly, thus making it easier to maintain the slide. Heck, motoGP guys have GPS based trac control that will change it's intervention based on which corner they're in.

As for dynamics of a highside, the rear breaks loose, then regrips causing a very high load on the rear shock. Moments later, the shock unloads, catapulting rider/bike. Like in motocross. It's the loading/unloading of the shock that provides the majority of air time, not necessarily speed.

Diggin' that theory...Being an ex-MX guy myself, it makes PERFECT sense!
Btw, I have the same sponsor!!! Small World