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hey since another forum i got to can be a bunch of assholes, can someone explain what a tankslapper is?

i just treid to ask a simple question about how people sit up and or what position they use to sit up when using only one hand on the bike. they said id have to ask squids when the simple fact of the matter is i see about 90% of sport bike riders doing this and there fully geared driving safe speeds etc. while i admit it may not be the safest way to ride im just curious. ive seen some lean over tanks, some with fist on knee, others hand on hip etc.

so any actual real info would be great thanks guys
 

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Hi SkinnyJ-

The brief definition of a tankslapper is oscillations from the front wheel and forks that will cause a motorcycle to become virtually uncontrollable. The reason it is called a tankslapper is because the handlebars will virtually "slap" the tank from both sides.

Here is a video of a tankslapper from the Isle of Man TT a few years ago.

~ Blue Jays ~
 

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What is really insane is to think about a tankslapper having the force to sling the damn brake pads/pitons out on the front calipers to the point that you have to pump your brakes to get braking back. :eek:
 

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Those are scary as hell...How do you even get into one?
Is it when you power wheelie and your bike loses alignment with the rear wheel?
 

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Tank slappers are scary. I researched what causes them after I had a really severe one making a 1-2 high RPM upshift (very stupid of me). The rear tire momentarily spun too fast for the bike's speed and slipped. I, being a "normal" person gave in to my survival reaction to let off the throttle and the rear tire bit hard. Though my wheels were barely out of alignment it was enough to cause massive head shake and I thought I was going to lose it. Happily, I somehow managed to keep the rubber in contact with the road long enough for the shake to disappear.

I now know that the proper way to deal with a tankslapper is to lift your hips up away from the seat and hold the bars firmly without giving any steering input. It is natural during a tankslapper to deathgrip the bars and squeeze your knees together on the tank as though you were holding on to a bucking bronco. This action translates the shake from your hands to the rest of the bike and destabilizes it. Lifting your body off the seat essentially disconnects the handlebars from the body of the bike and your body acts as a damper to lessen the steering head oscillations and stabilize the bike.

You'll notice in the video posted by Blue Jays that the rider's feet are off the pegs and thus he can't disconnect the forks and the rear portion of the bike. Thus, he cannot sufficiently dampen the oscillations and he crashes.

Moral of the story, stay loose and lift your weight off the seat. Don't panic!!!
Here is a link to a more thorough explanation.

http://www.everything2.com/index.pl?node_id=1460258
 

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Having had a number of REAL tankslappers in my many yrs of riding & especially competition or practicing even on dirt. Let me point out a REAL tankslapper & not a front fork wobble, is vicious & to my knowledge I think only one chap has recovered, going by his words, but then sometimes I do wonder about the latter still this is one of the best wheelie riders of the past few yrs.

The bike, for many reasons, will suddenly go completely out of control & in most cases to some the rider has lost one part of the handlebars & why the left being so common is beyond me. Still if you have both hands on the handlebars you still have lost control for the fue is being quickly turned ON & off with each snap & there are not to many snaps before you are sent flying off the bike.

Your body is being forced to the front of the fuel tank so you loose grip of one or both of the footrests.

The steering head stops are actually being toren off or bent & so the forks are slamming into the fuel tank & so the reason to be called "tank slapper" as the dings will show up in the petrol tank plus they can be quite deep.

I have actually been so far out of control that I was right up at the steering head with the bars hitting the upper parts of my legs just beofe I was sent flying.

What starts it I do not know, other then a slight wheelie can mean the front wheel does not land in the regular position of the bike, accelleration, & sometimes in trying to correct to much speed & so the rear wheel sliding out, so attempt to get the bike back in line which often is a "high sider".

For some yrs I had not noticed this on any bike & being brought up with very few paved roads then naturally gravel, cinder, or dirt roads were commong so I was accustom to the normal front end wobble over the above roads & naturally I practiced, road, & raced in dirt from '47 till '89.

Still when I purchased my '00 Honda 929 I noted the front end was far to light during break-in period & so the purchase of a Scotts steering head stabalizer & that was the answer to help. Yet it was not from a regular bike to the 929 for I had several hot trotting bikes like the screaming Yamaha RD/RZ 350LC bikes, my own cafe racers, to a Suzuki GSXR-750 I traded in on the 929, & a Yamaha YZF-600R. Also in the purchase of the '03 Honda 954 on went a Brit GBR steering head stabalizer.

So to confirm the thinking of some people last time I had a tankslapper was when racing a Bultaco 250 in a Cross Country event & I was coming down the side of a cliff at a high speed. I actually did not realize I had gone into a tank slapper & though I had simply lost control of the bike. Thing is the check crew saw me fighting the front end all the way till I was sent flying & sure enough the alloy tank was well dinged in both sides & steering head stops had be busted off. That was back in early 80s. The check crew that watched the above said they could not believe I had stayed on the bike that long AND others behind me took said downhill part of the cliff at a much slower speed, for I saw a rider stopped at the top when I shot by him without thinking it over & he warned others so their pace in coming down was much slower also with some normal prangs though no tank slappers FOR mine was SPEED.

Also at the Cross Country race I was POSITIVE I was in the lead only to see this rider in front & at the top of said steep downhill part (not realizing it was a rider that had starting problems so had made a short cut to the top of said part & was looking down at the steepness & how rough it was) when I went shooting by like stink.
 

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I dont know how many will agree with my definition, but to me, if its controllable its a headshake. If its not then its a tankslapper.
What happens is that for one reason or another the front tire looses traction, and regains it when its turned, and with the side of the tire. The steering head turns to correct, but over turns, thus swinging back and so it goes on and on.
On a strieght road, those shakes are controllable as long as the bars dont hit the steering stops. Once that happens it will act like a severe impact to the side of the frame from which it becomes very difficult to recover. Especially since less then a second later you will have another one.
If you have the presence of mind, what you need to do is get on the gas HARD. It will unload the front tire (maybe do a miniwheelie) and give you a chance to streighten the bars before the wheel touches down. you want to maintain a light grip on the bars, letting them wiggle in your hands, but still exerting some dampening force. if you grip them hard, you will have to deal with the headshake and a weave of the rear. Of course a severe tank slapper will often yank the bars right out of your hands, and at that point, you best option might just be to bail out. Another difficulty presents itself when you get a headshake right before a corner, since you dont have the time to streigthen the bike. On those situation you get to find out if luck is on yourside that day.
I've seen headshakes/slappers happen becouse of 4 different reasons.
1. Wheelie landing with the bar crooked, and the bike leaned to one side.
2. Hard acceleration coming out of the corner, with the bike still leaned.
3. Hard braking into a corner, to the point of momentary locking up the front tire. This seemed to be the case in Bluey's video.
4. Hard acceleration over some irregular surface that bumps the front wheel out of alignment (such as railroad tracks at an angle to the road, or some animal)

Sometimes headshakes grow in magnitude, starting out small and increasing. This is normally due to slowing down, thus increasing the weight on the front tire. If you ever feel a headshake, dont touch the brakes.
 

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Another thing to consider is, older or low powered bikes wouldn't mini-wheelie on throttle. So that solution might not always work, unless you're proficient at clutching it up on moment's notice. And although bikes with conservative geometry have less tendency, still the odds are there when circumstances are right. There was a lawsuit from Harley owners and police officers regarding few models of Harleys being unstable at high speed and front wheel wobbling.

When I was newer to riding, I know I even had a headshake from the little SV. It was a puckering moment since I didn't expect it, but it settled itself down quickly.
 

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Theory is one thing Vash & real life can be something else. Said second or five when you go into a tank slapper is so shocking you cannot go back to what your read or believed to be what you needed to do. True if you have the handlebars inhand you have a vague chance. Still in many cases I have hung onto the twist grip side, but not the left side. As for speed look at some of the tank slappers & in so many cases the rider starting to loose it might have a grip on both handlebars, BUT with the frantic & powerful snaps to the left & right one is turning up the throttle in one move yet turning it off in the next snap as I so mentioned.

Belive me said tank slappers are so shocking & so violent for the first second or two it is all you can do is to try & keep the bike under control ONLY every blow to the steering head stops or to the tank are ---around this time you start to think of what you should do only by the time you start to think you are being pitched off the bike. Remember we are talking about a few seconds like no more then 7 or eight.

I have seen them in scrambling with ridgid rear end bikes with no more travel in the forks the 2.5" so obviously the bike is bottoming & toppingto some with springer rear ends to even s/arm suspensions with latter only having 2" of travel. Seen them in Cross Country, Enduros, Flat Tracking & road racing. Actually I have had them in all of the above when practicing. Remember to often in the early years a 500cc single or twin punched out all of 25 to 27 HP though in road racing we would have them up to over 30hp. So in reality they were with no extra power to be given to the bike.

The last incident I mentioned was the speed of the Bultaco I was racing so obviously the extreme speed, along with all the rocks & such were to much so bike was bottoming & topping all the way down & downward one cannot turn the wick up any more for you are definately riding beyond your maximum ability which is also the nature of racing--------meaning you have no reserve left!!!!!!

Lastly you are correct in your thinking Fantic as I did point out, in the immediate above, that often one was riding probably at full chat or beyond their maximum ability.
 

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Smitty, I agree, its an asspuckering moment that takes lots of luck to get past.

Z: you dont have to fully lift the front tire, just unload it some.
 

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Now that the tank slapper question is covered, Ill answer the next question for you...


When I am only holding on with one hand, I am in one of several positions depending on my needs.

If my wrists start to go numb (long rides), I will rest my left arm on the tank and lean against it to relieve pressure for a few moments.

If my back is getting crampped up, I will put my left hand on the seat cowel behind me and sit as straight up as possible.

Often times, when riding down a long downhill, I will find myself doing something completely squid-like... (and definitly drummer-like) and I will take both hands off the handlebars and start drumming on the gas tank. Of course, as soon as I realize what I am doing, I will put both hands back on the handlebars.

I also find myself tugging at the bottom of my jeans a lot, which are usually flapping a bit too much for my comfort.
 

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ZX6R1033 said:
...I also find myself tugging at the bottom of my jeans a lot, which are usually flapping a bit too much for my comfort.
Of course, if you wore riding pants, this wouldn't be a problem. ;)
 

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I simply do not remove one or both hands from the handlebars. Like NEVER. The sportbikes have this lean forward riding position so you have to put your abs & back into work PLUS your knees.

Also all bikes are with adjustable levers to the hands & feet so you might need to adjust the hand levers a bit. I go out & ride my mtn roads for 4 to 7+ hrs steadily bar re-fuelling which gives me a chance to stretch a bit PLUS I will take a break some where along the run, usually on the way back. Possibly I will stop off for a cuppa or find a place I can park the bike & get under the shade of a tree. Often use my tankbag for a pillow & not uncommon for me to take a slight snooze----no matter what I will have relaxed.

Still no matter what nothing is tired. Mind you the riding position of the Yamaha YZF600R is not as extreme as the Honda 929 or 954 YET they are not as extreme as something like a Suzy GSXR-600, 750 or 1000------ for they are to extreme & I find I am straining my neck UP to see the traffic when going through a town or a small city. Small things are often why I will or will not buy a bike & the actual riding position is one. Yet I have been riding lean forward position since around '49 so I guess I am accustom to it. YET note I can find them to extreme.
 
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