How do I correct a back tire wobble at high speeds?

[Michael]

I have a "What to do in this situation" question:
How do I correct a back tire wobble at high speeds?

I have zero intention of doing wheelies, but in the first two crash videos below I notice that when the guys come down they wobble and crash. I assume this is because then didn't shift up and they're suddenly riding very fast at too low a gear. Is that correct?

However, if you're turning at high speed and your back tire starts to slide out a little, what is the best reaction? And what about when you're just going straight?

wheelie, wobble, crash
motorcycle crash 2 DZ

wheelie, wobble, crash
Motorrad Crash

38 seconds in to this video -- what should this guy have done?
Motorcycle Crash Compilation

High speed turn -- good recovery
GSXR 1000 K7 highsider

This guy doesn't correct and crashes into the wall
Motorcycle Crash

[Buckethead]

Large quantities of throttle.

 

[truckinduc]

most of those you posted are headshake, aka a "tankslapper"   which there a hundred threads devoted to if you search.

The Gsxr slide was almost a highside educed by the rider giving to much throttle while still leaned over, rear tire lost traction, then suddenly re gained it.

[Michael]

I've been searching and reading up on this a little, and I have some observations:

1) Keep your feet on the pegs, keep her steady, and accelerate out of the wobble.

2) As you accelerate out of a high speed turn, scoot your butt back a little to add more traction to the rear tire.

3) Firmly keep your handlebars straight if there is little or no traction on the front tire (to avoid tank slapping).

4) A steering damper would be a good investment.



"Because highside accidents are so much more deadly than lowside accidents, the Motorcycle Safety Foundation recommends that if a rider locks the rear brake, it should be kept locked until the motorcycle comes to a stop. If necessary, locking the front brake to deliberately cause a lowside is recommended."

- http://motorcycle-glossary.com/high-side/156

[Jester]

Man there are some crazy people on motorcycles.  That junk is why cagers think we all have death wishes.     I dunno.  Stunting just never seems to appeal to me.  Cool to watch, but not my bike.   

[Jester]

Man and that third video..........   That chick on the back of that one bike with a tank top on... I think she just got her breasts removed courtesy of ol' tarmac.

[corey]

the question is, is your back tire actually wobbling? is it really sliding? it could feel like it's sliding a mile, when it's really only sliding a very small fraction of an inch back there. we tend to panic at the first sense of lost traction, and the survival reaction of letting off the throttle kicks in.

letting off the throttle, while it seems like an easy solution to your problem, actually makes the situation worse. when you roll off, especially in a turn, you are suddenly destabilizing your suspension (which you worked so damn hard to stabilize during your corner entry), making controlling the bike smoothly even more difficult. by slowing down, you are also transferring weight to the front, which in fact is taking weight OFF of the rear wheel, which would actually further reduce its ability to hold good traction.

it's hard to fight that survival reaction. i'm still struggling with it.

as stated above, in those videos, the rear wobble is actually a front wheel wobble (head shake/tank slapper) that was transferred through the rider (probably holding onto the bars WAY to tight) to the BACK wheel.. Disastrous.

Be loose and light on the bars, make accurate steering inputs that you dont have to correct for, and when your tire does slide, feel like a badass about it and just continue to smoothly roll on through the turn. you'll be fine.

check out Twist of the Wrist II by Keith Code.
It's a difficult read, as he writes most of the book like some kind of Zen Master or something, but you do pick up a few good pieces of information.

[Michael]

Excellent advice. I think I'll get that book. I was looking on Amazon and you can buy both volumes of Twist of the Wrist and Total Control for about $45.

Also, there's a DVD of Twist of the Wrist. The reviews are funny. Apparently it was filmed so long ago and with such horrible, corny jokes that most people who watched it half expected to see David Bowie and a cast of muppets come out and start singing.

But at least the books got good reviews.

[corey]

$45 is a good buy. the books were i think $25 each, so your getting at least $5 off if they are brand new.
They are good reads, and aren't that lengthy, so you can plow through them in a week if you want. I did it at the beach.
As i said, his writing style is... unique... So you may even end up reading them twice.

I'm particularly fond of the section in "II" about Pivot Steering. I learned alot there.

[elmangaso]

letting off the throttle, while it seems like an easy solution to your problem, actually makes the situation worse. when you roll off, especially in a turn, you are suddenly destabilizing your suspension (which you worked so damn hard to stabilize during your corner entry), making controlling the bike smoothly even more difficult. by slowing down, you are also transferring weight to the front, which in fact is taking weight OFF of the rear wheel, which would actually further reduce its ability to hold good traction.

it's hard to fight that survival reaction. i'm still struggling with it.

This is exactly how I ended up low-siding my brand new Monster back in June...going into a tight right turn, very moderate speed (<20mph), I hit gravel and felt the back end start to slide...I let off the throttle and the back end started to chatter and slide even more. I knew what I did wrong  as soon as I got up off the pavement. Having read Twist of the Wrist II, I went through the book again (plenty of time to read while the bick was in the shop) and determined that I had also over-charged my 'lean angle credit card'. Basically going into turns leaning over like some MotoGP wanna-be left me with zero room errors...

[Dietrich]

Don't underestimate the power of your local public library for moto books either.  I've checked out TotW from the library. Have also seen several riding technique books pop up at Half Price Books. 

I'm not sure about all this sliding your butt around in the middle of high speed corner stuff.  Best advice is to anticipate road conditions by looking ahead (cattle gaurds come up a lot in tank slapper discussions), and stay loose.  If you're riding spritiedly, then your body position and alertness should match.

When I have days where it seems like my bike is handling like crap is when I realize I've had a death grip or been stiff-arming it the whole time.  Relax.  The bike will ride itself just fine, and even better, without you. 

I like Lee Park's recommendation to only steer with the inside arm, keeping your outside arm relaxed.  Makes things way more efficient, and takes another control input out of the equation.

On bikes with sport geometry, I believe a steering damper is a good investment, depending on how you ride or will be using the bike.

[corey]

I like Lee Park's recommendation to only steer with the inside arm, keeping your outside arm relaxed.  Makes things way more efficient, and takes another control input out of the equation.

This one piece of knowledge from Lee's book totally changed my riding.
Not only does it help create better, smoother steering inputs... It also helps to get rid of that "deathgrip" syndrome that is often a problem.

[UnCiviLMoNst3r]

I use to be a stunter on a R6 a while ago but that is something I have grown out of. You get wobble from 1 of three things. #1 You don't have enough air let out of your tire. With the tire being rounded of the bike will sway back and forth , just think of it as if your standing on a basketball trying to balance yourself.
#2 Body positioning when trying to maintain a balance point , that does include going up and coming down from a wheelie.
#3 When coming down from a wheelie most guys crash because they fail to roll into the throttle while landing and they sit the front tire down at an angle. At those speeds it's almost impossible to correct and get out of a wobble when you land it wrong even a stabilizer wont help you.

But I will admit that a steering stabilizer is the way to avoid a minimal amount of wobble. Hope that helped explain that aspect from those videos.

[OT]

Read Kevin Cameron's Sportbike Performance Handbook for a good intro into what causes MC instabilities and successes/failures of the various corrections tried over the years.

[Slide Panda]

Well a number of those bids showed very different situations - I could get the third one to load so that's out of my discussion.

That last vid has been floating around for a while. I've never seen anyone take a firm stance on what happened. There's something that you can't see that cased him to
loose traction. Perhaps something on the road. If he'd had more space he'd probably have recovered since it wasn't bad. But as we see it went bad

The 4 th was all about too much gas/not enough traction. His rear starts to loose traction and he chops the throttle. Less gas = more traction but his bike was getting side ways. As a result the tail snaps back into line when it grabs. As noted this is the classic highside formula.

Now the 1st and 2nd. In both cases it looks to me like the bring the front down rather hard with some bit of turn on the bars. Because of the turn the bike tries to sort itself out - much to the shock of the rider. Also with the forks completely compressed it makes a bad thing worse. You've decresed the trail and rake and used up all the ability for the suspension to compensate for any changes. Also the one dude was very far forward when he landed that just furthered his problems. That made sure the forks bottomed and also allowed the back end a greater freedom

So be smooth on your inputs. If you find you front wheel off don't chop the throttle. Hold it constant or ease up just a bit in a controlled manner. If you hold constant (given you're not to or past the balance point) will come cack down. Also a gentle touch on the rear brake can help settle things.

It should be pretty clear that you don't want to come down crossed up if possible. But if you do, being relaxed is important. If you have locked arms and a death grip you canmake s situation worse and actually contribute to head shake occurring. But if you're relaxed and light on the bars you can have an effect much like a mechanical steering damper does