tank slap

[hcr25]

The old saying "when in doubt gas it"
mike

[Bueller]

When recovering from a bad tank slapper make sure to check your front brakes for operation before you need them.
The large amount of flex to the front end can cause the pads to open up in the calipers, and may require a couple of pumps of the lever to close them back up. You don't want to find this out coming into a corner where you are really depending on having brakes.

[tarded400]

Yeah, thats what I figured...never really had a dirt bike before! I have only had one tankslapper and that was on my 929... Topped a little hill with a right hand corner, and the apex was right at the top of the hill. We were out in the middle of nowhere, so I was doing around 120 mph, and as soon as the bike went up and over the top of the hill it started to wobble. It didn't last very long or get very bad.

[Gramps]

My rear brake locked up after I slowed and I felt it fishtailing around until it righted itself.

this is a totally different subject

why are you using rear brake?(except for emergency stops)

[tarded400]

I've found a little bit of rear brake settles the chassis and keeps the rear on the ground a little bit.

[DavidofColorado]

this is a totally different subject

why are you using rear brake?(except for emergency stops)

I use both brakes. And I downshift. That is how I get down.

[wankel7]

I was merging onto 70 a few days ago and was leaned over a little and was really on the gas hard. Hit a bump and the front got light i guess. The handle bar shook just a little bit back and forth. I didn't fight but I did either maintain the throttle setting or kept accelerating. I really can't remember it happened so fast.

But it figured its self out

[Crashdaddy]

Despite the length of Pilot's essay answer, it is not the entire answer. The best riders in the world experience headshake, which is what it actually is, and when it gets extreme it may turn into a "tank slapper."

It is a phenomenon that has significantly increased since the invention of "sport bikes." And it has only gotten worse as the steering head angle has gotten steeper on modern sport bikes, and trail has decreased (Hence the steering dampers coming as original equipment on many bikes now). The upside is the quicker handling we enjoy, and the down side is unwanted instability. A rider using perfect technique, with a bike that is set up perfectly, can still experience headshake. It just might not be as bad as someone that has poor technique and suspension that sucks. It can be caused by something as simple as the front wheel touching down after a slight wheelie and not being perfectly straight before doing so.

The occurrence of headshake can also be increased if sag is not set up correctly for rider/motorcycle weight. If too much preload is dialed in the rear (not enough static sag), and too little preload (too much sag) in the front is combined with the jacked up (literally) rear, bad things can happen. When you have a bike's suspension screwed up like that, you have decreased the rake and the trail (think unicycle). It does not take much to upset the front end of a unicycle, does it?

I have experienced vicious headshake (tankslappers) on motocross bikes and a few sportbikes. There is one common thread...It always scared the shit (almost literally) out of me. The worst thing you can do is chop the throttle, as that loads the front, decreasing the rake even further. Unfortunatley, that is what most of us humans do.

As far as Pilot's tires cupping, it may be because that land yacht weighs as much as my truck. And has the rake of an OCC chopper. Very stable though.

[wankel7]

Well, I was riding today....maybe I was doing 25 or 30. Anyways, leaned back and was relaxing with my hands off the handle bars. And yep....it started to wobble....it looked like it was going to get worse with out input from me.

So, I leaned foward and held on the handle bars to stop it.






Good thing it was my mountain bike But it still surprised me to have the handle bars wobble like that

[Sortarican]

I can't find the clip, but it's of a rider coming up over a rise and going into a tank slapper.
He tries to fight it and ends up being tossed off the bike, which then rights itself, and rides off without him.
Great example of what happens when you try to muscle your way out of one.
(Anyone remember seeing it? I think it was from the IOM a few years back.)

[Bueller]

I can't find the clip, but it's of a rider coming up over a rise and going into a tank slapper.
He tries to fight it and ends up being tossed off the bike, which then rights itself, and rides off without him.
Great example of what happens when you try to muscle your way out of one.
(Anyone remember seeing it? I think it was from the IOM a few years back.)

Uhhhhhh........http://www.cosportbikeclub.org/forum...1&postcount=13

[Sortarican]

Uhhhhhh........http://www.cosportbikeclub.org/forum...1&postcount=13

I saw Scotts post, and yes that is what reminded me, but that's not it.
Searching IOM TT gets a billion hits.
.....but thank you for attempting to state the painfully apparent Captain Obvious.

[Bueller]

Wasn't sure you saw it since it only had a link and no picture, but it appears you're all over it.

[Sortarican]

Wasn't sure you saw it since it only had a link and no picture, but it appears you're all over it.

On it like a pit bull on Micheal Vick.

BTW,
Statement was made that the reduced rake and trail on sportbikes lends itself to tank slappers.(Makes sense)
As someone who's done a lot of riding on both sportbikes and sumos
do you notice less occurance of tank slappers on the sumos?

[Devaclis]

He never has the front wheel on the ground long enough to engage a tank slapper.

[Bueller]

I do have to bring the front down when I park it.
Actually about the same, since I have raised the forks a bit if I hit a transition in the pavement with only one hand on, it'll wobble, also dropping power wheelies with the wheel severely out of line will give you a thrill. I never had a slapper on the street with a sportbike, but on the track my worse one was due to a suspension adjustment (too much compression in the forks).

[Mae]

I have to say that this bike reaction is my biggest fear when it comes to riding & I am glad this thread was made so I could hear some ways to right the bike, prevent it or protect myself should it get too out of control.

[Raptor]

How much of a difference will a damper make in the way of prevention?

I'm guessing there's no schematic answer for this Q but how would you increase throttle in a gradual and controlled manner when your bars are flapping like a phychotic bird? How much does 'luck' factor into this? lol

[clustermagnet]

I'd let go of the bars and hope it would sort itself out.

lol... dont do that

[clustermagnet]

How much of a difference will a damper make in the way of prevention?

I'm guessing there's no schematic answer for this Q but how would you increase throttle in a gradual and controlled manner when your bars are flapping like a phychotic bird? How much does 'luck' factor into this? lol

Uhm... Dampers ... heh.

I think I have bugged just about everyone I know about this... so here is my personal experience:

stock dampers seem to be sufficient, never had issues on my 03gsxr600, street or track... I was never really fast on that bike however...

since the purchase of the 05 750 gsxr things have changed a bit ...

This entire season, after installing a ohlins steering damper, I kept finding myself dialing it back. There is a track in PA called BeaveRun, which has been the BEST place for me to learn to deal with head shake... It taught me to relax and not give a bleep. No matter how tight your damper is set, your bike will headshake at about 120-130 mph through the entire back section of the track.

another fun part was dialing off the damper just to get through the beginning of the track which is tight....

aaanyways...

there are racers that have a "looker" damper, no oil in it ... just to pass tech...

if your bike doesnt shake, you're fine... no damper will save you from a crash, its all in your head