Misti

I was just reading another post about a rider's experience with a highside. And while it is great that he is OK, I noticed that all of the talk about the crash was regarding the bike and gear damage. But what about the CAUSE of the Highside or what might have been done to prevent it from happening? What are the dynamics of a Highside?

Misti

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luvtolean

The dynamics? A force exceeding the mass of the rider multiplied by 9.81M/S^2 is momentarily exceeded in an upward direction by the force applied to the rider by the motorcycle, accelerating the rider into the air like a flicked booger.

Unfortunately that 9.81m/S^2 acceleration always ends up winning here on earth, and said booger, er rider, impacts the ground.

How do we prevent it? It, defined here as the booger smashing, is prevented by reversing that downward 9.81m/S^2 acceleration of course.

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phobe

Pin it and lowside instead.

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Shenders1

Sounds to me like you've described the dynamics of the launch portion of a highside .

Seriously, I've got the same question. When the rear loses traction, what causes it, 9 times out of 10 anyway, to catch? Can't always be due to rider lifting throttle...

Something to do with the increasing slip angle between rear tire and pavement coupled with rapidly dropping center of gravity I betcha. Maybe.

BobcatSig

As a junkie fancying a addiction-fueled race endeavor, these sorts of information would be quite valuable in the time between track days and instructions. I'm anxious to hear the responses!

DrHall

That has been my usual plan...

Barring that, the olny other option I have used is being a total wuss on the throttle coming out of corners. I am hoping for a middle ground. When I raced in the dirt and rode off-road extensively, sliding the back end was a given, part of the game. Highsides were possible (trust me ), but not as prevelant as the seem to be on the road race course. The power, traction and speed we are moving tend to intensify the speed of events and their results on the paved track.

I would love to hear some real answers and experience on how to avoid being the booger in LTL's enlightening, and well stated, example.

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Hammer

I do not know the technical terms to explain a highside, but i have it mastered.

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luvtolean

The same way you avoid syphilis, avoid the fun part.

Barring that, if you have the time to think about it, don't chop the throttle when the rear lets go.

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luvtolean

I can describe the tumbling part too if you want, it just seemed the smash part was the feature of the event to avoid, and thus address.

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bwhip

Guilty as charged...

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DrHall

Avoid the fun part...

That is the part that gets me, I have watched a lot of highside vids, and it seems that many times there is no throttle chop. It happens so fast I can't really tell, though.

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nhfirefighter13

Delusions of grandeur?

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seamus

If that were the case, I'd highside out of my bed each morning.

And sometimes in the middle of the night, too.

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nhfirefighter13

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SheepOfBlue

... yep used to have a saying on the dirt "when in doubt gas it"

Personally when the back has stepped out on the RC I just kept steady throttle and it rehooked. But I have close up video of what happens when you wack it closed.

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slickwill

Well I can say that I can induce a "highside" at will with my 2-stroke RC truck. It definitely seems to come from the rear end hooking up too suddenly when the throttle is chopped. If I let off easy it will make it out, or if I just keep the throttle pinned it will usually spin out of control. For something so small with such a low center of gravity it is amazing how far the truck will launch when it happens. I'll try to get some video of it sometime. I wish I had datalogging on it.

On that note I'd love to see the datalogging off of a GP bike before, during, and after a highside.

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phobe

Guessing here... powered rear wheel follows the front wheel, breaks traction, accelerates laterally and tries to pass the front wheel. Rider lets go of the throttle, rear wheel slows under compression braking, pulling it abruptly back in line to follow the front wheel. Tires roll immediately back onto the apex of their profile, thrusting the bike upwards and causing the rider to detach from it, fly through the air and break both of his feet in the landing.

But what if it's on a treadmill?

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CBRVFR

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BobcatSig

You guys slay me!
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Baketech

These two articles generally create some forum fodder...

Motorcycle Safety Site

motorcycle dynamics

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ND4SPD

The one(and only) time I highsided, it happened fast enough that I didn't have time to react. So fast in fact, that I didn't even realize that I smashed the left side of my bike until I saw it being pushed into the pits. The only other hint I had was that my left foot hurt like hell and could barely stand on it.

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luvtolean

I have the data trace of one, except on a hack-built 929 instead of a GP bike.

The line gets really squiggly...

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CBR929RE

first off I'd like to say I am not a booger.


I doubt I even had time to think about that. also not sure that would have been the best idea because it could have propelled me into the concrete wall.

basically all I really had time to think when the rear went sideways was "this is gonna end badly" then in the air "fuck my bike is gonna be really damaged"

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