How do you save tankslap, aka speed wobble?
- Thread starter TheGsxr6
- Start date
Schtum
Free Genie
FWIW - a very long time ago when the world was young, I borrowed a friend's BMW R75/7. It was shod with Dunlop TT100s which, at the time, was recognised as a complete no-no. The only tyres which had stiff enough carcases to damp out the oscillations of the old airhead's flexible frame were Continentals and Metzlers. It was well known that the Dunlops were prone to instability and possible tank slappers.
This didn't seem to bother my buddy - partly because he was a big guy and his mass damped out any oscillations before they developed into anything bigger. However, at the time I was probably 140 lbs, dripping wet and on the way home one evening on his bike, I hit a dip in the road at c. 80 mph and the Beemer immediately began to shake its head quite violently. I remembered reading that one way to stop this was by standing up on the pegs and leaning forward over the steering head so I very quickly assumed the position; almost peering at the headlamp glass. The bike stopped shaking its head, I sat down and carried on my merry way.
As ever - YMMV.
This didn't seem to bother my buddy - partly because he was a big guy and his mass damped out any oscillations before they developed into anything bigger. However, at the time I was probably 140 lbs, dripping wet and on the way home one evening on his bike, I hit a dip in the road at c. 80 mph and the Beemer immediately began to shake its head quite violently. I remembered reading that one way to stop this was by standing up on the pegs and leaning forward over the steering head so I very quickly assumed the position; almost peering at the headlamp glass. The bike stopped shaking its head, I sat down and carried on my merry way.
As ever - YMMV.
flying_hun
Adverse Selection
What preceded your tankslapper? A wheelie? Something else?
Lou will be here soon to tell you to get a Scott's steering damper. Probably good advice. It shouldn't hurt anything but your wallet. :teeth
My suggestion is to stay as loose on the bars as possible, keep looking where you want to go, and gently accelerate.
The best recovery I've ever seen was the late great Martin Finnegan at an Irish superbike race. He landed from a jump crossed up at well over 150 mph. The bike began to slap violently, so Martin did the only logical thing - he clutched up a huge wheelie to settle it down! :loco No front wheel on the group = no tankslapper. :laughing No, I haven't tried out his approach. :teeth
Lou will be here soon to tell you to get a Scott's steering damper. Probably good advice. It shouldn't hurt anything but your wallet. :teeth
My suggestion is to stay as loose on the bars as possible, keep looking where you want to go, and gently accelerate.
The best recovery I've ever seen was the late great Martin Finnegan at an Irish superbike race. He landed from a jump crossed up at well over 150 mph. The bike began to slap violently, so Martin did the only logical thing - he clutched up a huge wheelie to settle it down! :loco No front wheel on the group = no tankslapper. :laughing No, I haven't tried out his approach. :teeth
AkatomboRR
"the first of his name"
I was able to get out of one by going easy on the handle and ride through it.. It was a small one.
russ69
Backside Slider
OK there are two kinds of tank slappers. One is a quick 3 oscillation swing that happens when the front end is light and you are under power. These self damp by the 3rd swing but it is caused by the front wheel being partially unloaded and the power twisting the front end/chassis. The other kind is more scary, that would be the click to click full-on slapper. Front tire chirping with each lock to lock movement. These are the bad ones.
In both cases if you lower the power the front wheel will take a better set and lessen the gyrations but it may or may not be recoverable. The general rule for the little ones is that if it doesn't feel like it's getting worse, then keep the gas on and ride through it, bikes wobble, no big deal. The real, click to click, tank slappers are much more serious, your hands might be stripped from the bars before you can get the bike settled but you want to reduce power and gently try to get control. The bike will decide if you win this contest or not. My rule is that by the 4th click, you are usually in trouble, look for a soft place to land.
In both cases if you lower the power the front wheel will take a better set and lessen the gyrations but it may or may not be recoverable. The general rule for the little ones is that if it doesn't feel like it's getting worse, then keep the gas on and ride through it, bikes wobble, no big deal. The real, click to click, tank slappers are much more serious, your hands might be stripped from the bars before you can get the bike settled but you want to reduce power and gently try to get control. The bike will decide if you win this contest or not. My rule is that by the 4th click, you are usually in trouble, look for a soft place to land.
ScottRNelson
Mr. Dual Sport Rider
It appears that a lot of people think a little bit of headshake is a tankslapper. If the bars aren't going full lock, it's just headshake and you can usually ride it out easily enough.
The last time I had a true tankslapper, in 2003, I wasn't able to keep hold of the bars for long and the rapid, violent oscillations broke a bone in my left hand and dislocated my thumb in two places. I'm convinced that once it started, there was nothing that I could have done to recover.
I've had a couple of quick tankslappers on dirt bikes, but it's much easier to recover when riding on dirt after three or four oscillations.
The last time I had a true tankslapper, in 2003, I wasn't able to keep hold of the bars for long and the rapid, violent oscillations broke a bone in my left hand and dislocated my thumb in two places. I'm convinced that once it started, there was nothing that I could have done to recover.
I've had a couple of quick tankslappers on dirt bikes, but it's much easier to recover when riding on dirt after three or four oscillations.
sliverstorm
Well-known member
Absolutely. On some of the less-stable bikes I've ridden, I've let go of the bars while going straight, and as soon as the weight transfers forward the bars would start to gently oscillate. Hopefully not many of you are riding bikes that bad anymore, but just as a sort of proof-of-concept anecdote
Odd, when I was in that position on my old 929 it REALLY wanted to shake it's head. I was doing it in order to get the front wheel up, though.
I've got a pretty decent steering damper on my bike, so I'm not all that concerned about tankslappers. It's turned down pretty far, and I rarely need it, but there have been times that I've been glad that it was there. The ass end of my bike is quite a bit higher than stock, and the front end is somewhat lower.
CuriousMike
Well-known member
You can't really do anything when you're arms and feet have been thrown off the bars and pegs.
I'm talking about you, CBR 929.
I'm talking about you, CBR 929.
Gabe
COVID-fefe
I'm guessing you didn't take the MSF BRC (and then my question is, "Why didn't you?). If you had, you would have learned about dealing with "wobble or weave." The advice given in the MSF text is to slowly and smoothly back off the throttle while keeping a firm (but not death-grip) hold on the bars. Do not accelerate to deal with it. When the bike gets back under control, pull over and figure out why the bike did what it did. Is it underinflated tires? Steering-head bearings? Overloading with luggage or a passenger? You can check for all that by the side of the road.
In my opinion, steering dampers are a band-aid masking a symptom for a problem with bike setup. Racers and trackday guys have them for insurance. A streetbike shouldn't need them (unless you are riding way faster than I'd reccomend on the street).
In my opinion, steering dampers are a band-aid masking a symptom for a problem with bike setup. Racers and trackday guys have them for insurance. A streetbike shouldn't need them (unless you are riding way faster than I'd reccomend on the street).
Flying Pig
Still learning to ride
russ69
Backside Slider
Neither. You will know when you are in a real tank slapper, you'll shit yourself. It's hard to see in the video but that looks like the bike is just skating around.
russ69
Backside Slider
Yeah, OK. My Mach III had both a friction damper and a piston damper when it went stop to stop on me, granted that was early seventies but a damper is a band-aid to a serious problem.
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Carlo
Kickstart Enthusiast
Definately NOT a tankslapper. The word derives from the fact that the front forks are slapping the tank, or as nearly slapping the tank as the steering locks will let it.
I'm guessing that Schtum experienced a true tankslapper on the old airhead, while our OP had experienced simple oscillations of the fork (aka "speed wobble").
I've gone through fork oscillations on numerous bikes over the years, and recovered from all of them.
AkatomboRR
"the first of his name"
Okay I had headshake and not tankslap.. Either way it was scary... :|
I rarely get much headshake. I've got pretty aggressive geometry - the front of my bike is lower than stock, and yet the bike leans WAY over on the kickstand - but it's pretty stable. Sure, it'll wag the front end a little if I'm hard on the gas out of a turn over bumps, but that's about it. For some reason, this SV both turns quicker and is more stable than my old 929.
Gnarly Cranium
milk crate goes where?
So I'm guessing an actual tank slapper looks something more like this?
http://www.youtube.com/watch?v=XiKmPFo6xNA
(why is it that youtube embed seems to have broken lately? I just keep getting a white box)
http://www.youtube.com/watch?v=XiKmPFo6xNA
(why is it that youtube embed seems to have broken lately? I just keep getting a white box)